NORDIC nRF9160 Development Kit User Manual
- June 16, 2024
- NORDIC
Table of Contents
nRF9160 Hardware Design Guidelines
nWP-037
White Paper
Revision history
Date | Description |
---|---|
2022-09-27 | • Added External flash memory requirements on page 28 |
• Editorial changes
September 2020| First release
Introduction
This document provides guidelines for the hardware design and integration of nRF9160. These guidelines will help to ensure the best electrical, mechanical, and thermal performance of nRF9160. The guidelines are intended for Nordic Semiconductor’s customers, especially system integrators and hardware engineers.
Related documentation
In addition to the information in this document, you may need to consult other
documents.
Information related to the integration of nRF9160 is provided in the following
documents:
- nRF9160 Product Specification
- nWP033 – nRF9160 Antenna and RF Interface Guidelines
- nWP034 – nRF9160 Hardware Verification Guidelines
- nRF91 AT Commands Reference Guide
Design overview
This section provides an overview of the operating conditions of nRF9160 and a pinout with a description of each pin. Recommended baseline schematics are also provided illustrating a good starting point for the integration of nRF9160.
3.1 Operating conditions
This section describes the operating conditions that impact the performance
and behavior of nRF9160.
3.1.1 Temperature range
The optimal operating case temperature (Tc) of nRF9160 ranges from –30°C to
65°C, achieving the best RF performance including output power transmission
and receiver sensitivity.
nRF9160 remains 3GPP compliant in case temperatures that range from –40°C to
85°C. Case temperature is typically the main cause for degradation in RF
performance and current consumption, but other factors,
such as supply voltage and signaling parameters, may contribute to it as well.
Case temperature is affected by the ambient temperature combined with
nRF9160’s internal thermal dissipation originating from the LTE modem and
application processor’s activity.
3.1.1.1 Thermal protection
nRF9160 has a built-in thermal protection mechanism to prevent RF Power
Amplifier (PA) from breaking and the LTE modem from operating beyond the
specified temperature range.
When the internal temperature sensor in nRF9160 measures a case temperature of
approximately 90°C, the LTE modem and Global Positioning System (GPS) receiver
are deactivated to minimize the internal generation of heat and to protect RF
PA. When the sensor measures a temperature that is lower than approximately
90°C, the LTE modem is reactivated. Using the application processor is not
limited by the thermal protection mechanism.
For more information on thermal protection, see Internal temperature
%XTEMP
in nRF91 AT Commands Reference Guide.
3.1.2 Voltage range
The operational voltage of nRF9160 ranges from 3.0 V to 5.5 V. The modem
transceiver requires a minimum voltage of 3.3 V to fulfill RF performance in
the environmental conditions described in nRF9160 Product
Specification.
The RF performance and environmental specification described in nRF9160
Product Specification exceed the equivalent requirements in the 3GPP
specification. Therefore, nRF9160 is 3GPP compliant with supply voltage down
to 3.1 V.
Note: Minimum voltage includes all voltage drops, ripple, and spikes.
3.1.3 Physical characteristics
The physical dimensions of nRF9160 are 16.0 x 10.5 x 1.0 mm. It has a plastic
compound mold and integrated metallization to suppress internal radiated
emissions and protect against external radio interference.
3.1.4 Supported cellular bands
A list of certified cellular bands can be found in nRF9160 certifications.
3.2 Pinout
This section describes the physical pin mapping and functions of the pins in
nRF9160.
3.2.1 Pin assignments
The nRF9160 pinout has 127 pins.
The pin assignment of nRF9160 is shown in the following figure:
For more information, see nRF9160 Product
Specification.
3.2.2 Pin description
Each nRF9160 pin has specified functions and design recommendations. The
detailed design recommendations are provided in Hardware integration on page
15.
The following table describes the functions of the nRF9160 pins.
Pin no | Pin name | Function | Description |
---|---|---|---|
1 | GND_Shield | Power | Microshield ground. Connect to VSS (pin 103) |
and application board ground.
2| P0.05| General-Purpose Input/Output (GPIO)| Digital I/O,
VDD_GPIO level.
3| P0.06
4| P0.07
5–9| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
10| Reserved| | Connect thermally and mechanically to the application
board, but leave electrically unconnected.
11| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
12| VDD_GPIO| GPIO power supply input and logic level for GPIOs.
13| DEC0| nRF9160-internal supply capacitor connection.
14| GND_Shield| Microshield ground. Connect to VSS (pin 103) and
application board ground.
15| P0.08| GPIO| Digital I/O, VDD_GPIO level.
16| P0.09
17| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
18| P0.10| GPIO| Digital I/O, VDD_GPIO level.
19| P0.11
20| P0.12
21| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
22| VDD2| nRF9160’s PA PMU supply input. Must be at the same voltage
level as VDD1 (pin 102) supply for the System on Chip (SoC).
23| P0.13| GPIO| Digital I/O and analog input, VDD_GPIO level.
24| P0.14
25| P0.15
26| P0.16
27| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
28| P0.17| GPIO| Digital I/O and analog input, VDD_GPIO level.
29| P0.18
30| P0.19
31| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
Pin no| Pin name| Function| Description
---|---|---|---
32| nRESET| System reset| SoC reset.
33| SWDCLK| Serial Wire Debug (SWD)| SWD and programming clock
input.
34| SWDIO| SWD and programming interface.
35| P0.20| GPIO| Digital I/O and analog input, VDD_GPIO level.
36| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
37| P0.21| GPIO| Digital I/O and trace buffer clock, VDD_GPIO level.
38| P0.22| Digital I/O, VDD_GPIO level.
39| P0.23
40| P0.24
41| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
42| P0.25| GPIO| Digital I/O, VDD_GPIO level.
43| SIM_RST| Subscriber Identity Module (SIM)| SIM reset.
44| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
45| SIM_DET| SIM| SIM detect (currently not a supported feature).
46| SIM_CLK| SIM clock.
47| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
48| SIM_IO| SIM| SIM data.
49| SIM _ 1V8| SIM card’s 1.8 V power supply output.
50| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
51| Reserved| Reserved| Connect thermally and mechanically to the
application board but leave electrically unconnected.
52| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
53| MAGPIO2| GPIO| Digital I/O. Controllable by application processor
and LTE modem, fixed 1.8 V.
54| MAGPIO1
55| MAGPIO0
56| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
57| VIO| RFFE ctrl| Digital I/O. MIPI RF Front-End Control Interface
(RFFE) VIO compatible, fixed 1.8 V.
58| SCLK| Digital I/O. RFFE CLK compatible, fixed 1.8 V.
Pin no| Pin name| Function| Description
---|---|---|---
59| SDATA| | Digital I/O. RFFE DATA compatible, fixed 1.8 V.
60| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
61| ANT| RF| Cellular antenna port, 50 Ω.
62| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
63| GND_Shield
64| AUX| RF| Loopback port for cellular antenna. A matching network
external to the module is recommended.
65| GND_Shield| Power| Microshield ground, connect to VSS (pin 103)
and application board ground.
66| GND_Shield
67| GPS| RF| GPS receiver antenna port, 50 Ω.
68| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
69| GND_Shield
70| Reserved| Reserved| Connect thermally and mechanically to the
application board but leave electrically unconnected.
71| Reserved
72| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
73| Reserved| Reserved| Connect thermally or mechanically to the
application board but leave electrically unconnected.
74–82| GND_Shield| Power| Microshield ground. Connect to VSS (pin
103) and application board ground.
83| P0.26| GPIO| Digital I/O, VDD_GPIO level.
84| P0.27
85| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
86| P0.28| GPIO| Digital I/O, VDD_GPIO level.
87| P0.29
88| P0.30
89| P0.31
90| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
91| COEX2| GPIO| Controlled by modem.
92| COEX1
93| COEX0
94| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
Pin no| Pin name| Function| Description
---|---|---|---
95| P0.00| GPIO| Digital I/O, VDD_GPIO level.
96| P0.01
97| P0.02
98| GND_Shield| Power| Microshield ground. Connect to VSS (pin 103)
and application board ground.
99| P0.03| GPIO| Digital I/O, VDD_GPIO level.
100| P0.04| Digital I/O, VDD_GPIO level.
101| ENABLE| Control| < 0.4 V disable, > 0.8 x VDD1 enable.
102| VDD1| Power| nRF9160 SoC PMU supply input. Must be at the same
voltage level as VDD2 ‘s (pin 22) supply for PA.
103| VSS| nRF9160 ground plane. Ensure the connection to the application
board ground is solid for good electrical, thermal, and mechanical robustness
performance.
104–127| Reserved| Reserved| Connect thermally and mechanically to the
application board but leave electrically unconnected.
Table 1: Pin assignments
3.3 Schematic design
The schematic design should start from the most important nRF9160 interfaces
which are the supplies and radio frequency interfaces. The SIM and control
interfaces should also be prioritized, as they may require special application
components, for example, for Electrostatic Discharge (ESD) protection.
The following figure shows recommendations that can be used as the basis of
the application’s schematic design.
The following table provides information on recommended components:
Reference | Description | Quality | Example part number |
---|---|---|---|
C1 | CAP, 15 pF, 25 V, C0G, 0201 | X5R, 10 V or better | GJM0335C1E150JB01 |
C2 | CAP, 100 nF, 10 V, X5R, 0201 | GRM033R61A104KE15 | |
C3 | CAP, 47 uF, 10 V, X5R, 0805 | GRM21BR61A476ME15 | |
C5 | CAP, 100 nF, 10 V, X5R, 0201 | GRM033R61A104KE15 | |
C6 | CAP, 4.7uF, 10V, X5R, 0402 | GRM155R61A475MEAA |
C7
C8| CAP, 15 pF, 25V, C0G, 0201| GJM0335C1E150JB01
C9| CAP, 100 nF, 10 V, X5R, 0201| GRM033R61A104KE15
C10| CAP, 47 uF, 10 V, X5R, 0805| GRM21BR61A476ME15
C12| CAP, 100 nF, 10 V, X5R, 0201| GRM033R61A104KE15
C13
C141| Optional. Not recommended to be assembled by default.| GJM0335C1E100JB01
C151
C162| GRM033R61A104KE15
R/L/C| Antenna matching| High-Q components, for example, Murata LQW15AN series
inductors and GJM1555C1 series capacitors
L/C
R1| 10 kΩ resistor| NA| RC0201FR-0710KL
R2| Resistor in the range of 1 kΩ| RC0201FR-071KL
R3
R4
Table 2: nRF9160 application component recommendations
1 CAP, ≤10 pF, 5%, 25 V, C0G, 0201
2 CAP, 100 nF, 10 V, X5R, 0201
For recommended matching component values and topology, see the datasheets of
the LTE and GPS antennas. For more information on the antenna design and
interface, see nWP033 – nRF9160 Antenna and RF Interface
Guidelines.
Hardware integration
This section provides design recommendations and layout guidelines for each nRF9160 pin for a successful integration of nRF9160.
4.1 VSS
VSS (pin 103) is the main electrical ground connection between nRF9160 and the
application board. It is also the main thermal dissipation path from nRF9160
and the main mechanical connection.
The connection between VSS and the application board must be electrically,
thermally, and mechanically strong. It is recommended that the application
board Printed Circuit Board (PCB)’s ground planes around nRF9160 are as intact
and as solid as possible. Use as many ground vias as possible between the top
metal layer of the application board and the inner ground layers connected to
nRF9160’s VSS pins. Typically, metal filled vias provide the best thermal
conductivity.
4.2 GND_Shield
The following ground pins are dedicated for the embedded microshield: 1, 5–9,
11, 14, 17, 21, 27, 31, 36, 41, 44, 47, 50, 52, 56, 60, 62, 63, 65, 66, 68,
69, 72, 74–82, 85, 90, 94, and 98.
Connect GND_Shield electrically strongly to VSS (pin 103) and on the
application board to the same ground planes as VSS.
4.3 ENABLE
ENABLE (pin 101) is a high-impedance control pin for the nRF9160-internal PMU.
It is used to enable and disable nRF9160. Logic high (> 0.8 x VDD1) enables
nRF9160. The start delay is in the range of a few milliseconds from pulling
the ENABLE pin high. Logic low (< 0.4 V) disables nRF9160 and brings it into
extremely low current consumption.
In products where nRF9160 is always enabled, the ENABLE pin can be connected
to VDD1 (pin 102) on the application board with a series resistor. The series
resistor minimizes digital noise coupling between the VDD1 and ENABLE pins. It
is recommended to add a decoupling capacitor to the ENABLE pin. If ENABLE is
connected to VDD1, a shared capacitor can be used for the ENABLE and VDD1 pins
if the VDD1 decoupling capacitor is located close to the VDD1 and ENABLE pins.
4.3.1 PCB layout design
When designing the PCB layout, pin-specific recommendations should be
followed.
The ENABLE pin has the following recommendations:
- Place R1 close to the ENABLE pin.
- If ENABLE is directly connected to VDD1, it can use a shared decoupling capacitor with VDD1 if VDD1’s decoupling capacitors and ENABLE are located close to each other.
- If ENABLE is not directly connected to VDD1, a dedicated decoupling capacitor is recommended to be added to the ENABLE pin.
- Because ENABLE can carry noise from internal and external regulators and the power source, it is not recommended to be routed parallel to sensitive routings, such as RF.
- Avoid routing the Enable signal unshielded on the top and bottom metal layers of the PCB. This risks radiated noise that can deteriorate radiated GPS and LTE sensitivity.
4.4 VDD1 and VDD2
Power supply design is one of the main factors in achieving good RF
performance, low current consumption, and reliable behavior of a product over
its life time in various conditions. VDD1 (pin 102) and VDD2 (pin 22) are the
main power supply inputs for nRF9160 and form the combined VDD. VDD1 is
connected to the DC converter input of the nRF9160-internal PMU that supplies
the SoC.
VDD2 is connected to the DC converter input of the nRF9160-internal PMU that
supplies the RF PA. The operational voltage of VDD1 and VDD2 ranges from 3.0 V
to 5.5 V. To comply with the RF performance specifications in Electrical
specification
in nRF9160 Product Specification, the inbuilt LTE modem transceiver is not
recommended to be used below 3.3 V, even though nRF9160 can operate down to
3.0 V.
To ensure the operation described in nRF9160 Product Specification, prevent
voltage drops, ripple, and spurious below 3.3 V in VDD. Voltage drop is most
likely to occur during LTE transmit. This is due to peaks of up to 500 mA/3.3
V happening during VDD2 current consumption. VDD must not drop below 3.0 V
during any nRF9160 operation. To minimize supply voltage ripple and suppress
EMI coupling to/ from nRF9160, it is recommended to place low ESR capacitors
close to the VDD1 and VDD2 pins. Supply
capacitors of low ESR (<0.1 Ω) are recommended.
To improve power delivery, voltage ripple, and EMI performance, it is
recommended to have at least one low ESR supply capacitor C3 in VDD1 and C10
in VDD2. Placing ferrite bead FB1 at VDD1 is highly recommended. To further
improve filtering for high-frequency components, you can optionally add C2 and
C1 to VDD1 or C9 and C8 to VDD2. The electrical values for C2 and C9 may vary
depending on the application, but for C1, the recommended range is from 1 nF
to 470 nF, and for C8, it is from 10 pF to 100
pF.
For VDD_GPIO, the minimum recommendation is low ESR supply capacitor C6.
Filtering for highfrequency components can be improved by adding C5 in the
range of 1 nF to 470 nF.
To improve the supply network’s EMI performance, a series three terminal
filter capacitor can be added close to the battery. For example, Murata
NFM15PC can be used. The filter capacitor attenuates unwanted noise generated
at wide frequency range approximately from 10 MHz to 3 GHz.
Note: VDD1 and VDD2 must be connected to the same supply voltage.
4.4.1 PCB layout design
When designing the PCB layout, pin-specific recommendations should be
followed.
The VDD1 and VDD2 pins have the following recommendations:
- Place low DCR (<0.1 Ω) ferrite bead FB1 closest to the VDD1 pin to suppress noise from nRF9160.
- Place capacitors C4 (C11) and C3 (C10) close to the VDD pins for improved power delivery.
- Place capacitors C1 (C8) and C2 (C9) close to the VDD pins to filter high-frequency signal components, especially if the product integrates an internal LTE or GPS antenna.
- Connect capacitors to the same ground plane as nRF9160 (pin 103) using low impedance ground connections.
- Use wide enough tracks (DCR <0.1 Ω) for VDD routing to minimize voltage drops and unwanted power consumption coming from routing losses under high current conditions.
- Avoid supply routings close or adjacent to sensitive routings, such as RF.
- Use shielded PCB layers for routings whenever possible to minimize radiated noise.
- Use plenty of ground vias along supply routings to minimize unwanted voltage differences in the application PCB’s metal layers.
- A series solder bridge is recommended in the VDD routing for current consumption measurements or other diagnostic purposes.
Note: Short low impedance ground connections are mandatory for all supply capacitors.
4.4.2 VDD current consumption
During operation, nRF9160 current consumption depends significantly on the LTE
network, end product’s antenna design, temperature, battery voltage, and the
intensity of the LTE uplink data transmit. Although the typical current
consumption of nRF9160 can be very low, the power supply and system must be
designed to meet the demands of the potential worst-case level of current
consumption.
The worst-case level of current consumption depends, among other things, on
the following:
- The temperature range for which the end product is certified.
- The cut-off voltage of the end product’s power supply.
- The antenna impedance mismatch behavior when the end product is placed on a metal surface or covered by the user’s hand.
The current consumption figures related to hardware design are given in Modem current consumption in nRF9160 Product Specification:
- Radio resource control (RRC) current consumption figures equal to average current consumption over radio frame (10 ms) with up and downlink data transmission in nominal operating conditions.
- Peak current consumption figures in nominal operating conditions equal to average current consumption during uplink transmission in nominal operating conditions.
- Peak current consumption figures in extreme operating conditions equal to average current consumption during uplink transmission in extreme operating conditions. This means Tc >65°C and antenna mismatch of VSWR3:1. In the design of the end product’s supply, this is the most stringent target to comply with.
4.4.3 LTE-M and LTE-NB
HD-FDD LTE-M and HD-FDD LTE-NB have different uplink ratios over radio frame
and maximum continuous uplink durations. Both systems are based on a 10 ms
radio frame consisting of 10 subframes (SF), 1 ms each.
In normal network signaling conditions without uplink repetitions, the number
of continuous uplink and downlink subframes may differ noticeably between the
systems. In HD-FDD LTE-M, the maximum uplink ratio can be 3 SF/10 SF (33%),
whereas in HD-FDD LTE-NB it can be 8 SF/10 SF (80%). This means that in HD-FDD
LTE-NB, the uplink can be transmitting approximately three times longer per
radio frame than in HD-FDD LTE-M.
However, with uplink repetitions, both systems share the same uplink ratio of
86%. Power consumption at high output power levels for HD-FDD LTE-M is
approximately 15% higher than HD-FF LTE-NB. Power supply design requirements
are the most rigid for LTE-M.
Note: The end product’s power supply and thermal design must comply with the worst-case consumption level. This prevents nRF9160 from occasionally resetting which generates extra current consumption. It also helps reduce overhead in the LTE network connection. Too much overhead could cause the network operator to block the end product from the network.
4.5 VDD_GPIO
VDD_GPIO (pin 12) is the supply for application GPIOs P0.00–P0.31 and the COEX
interface (pins 91–93) that is provided externally.
The operating voltage of VDD_GPIO ranges from 1.8 to 3.6 V and is independent
of the VDD supply. The GPIOs have software-configurable drive modes. In
standard drive mode, pin sink and source currents are approximately 0.5 mA. In
high drive mode, pin currents are 3 to 5 mA. The standard drive mode is
operational over the voltage range of 1.8 to 3.6 V. High drive mode is
operational over the voltage range of 1.8 to 3.6 V, but 5 mA drive current
requires VDD_GPIO voltage of ≥ 2.7 V.
Standard drive is recommended because lower current results in better EMI
performance and interoperability with other application board peripherals.
With standard drive, the end product’s performance regarding items, such as
LTE radiated spurious emissions and LTE receiver radiated sensitivity, is
typically somewhat better than with high drive.
Unlike the current consumption of VDD, VDD_GPIO’s current consumption is
mostly controlled by the end product design. This is because VDD_GPIO supplies
the application GPIOs which are controlled by the application software
provided by the integrator. If the GPIOs are not significantly stressed in the
device, VDD_GPIO can have a simple power supply strategy. However, if the end
product has high momentary current draw from the GPIOs, VDD_GPIO’s capability
must be designed to comply with it. In the worst case, the momentary
concurrent current consumption of all GPIOs should not peak higher than
approximately 100 mA. Regardless of the VDD_GPIO’s supply capability, it is
not recommended to have long periods of high concurrent consumption because it
increases the risk of reducing the device’s lifetime.
Recommended VDD_GPIO decoupling capacitors are shown in Table 2: nRF9160
application component recommendations on page 14.
The following restrictions apply to the VDD_GPIO pin:
- VDD_GPIO should be applied after VDD has been supplied.
- VDD_GPIO should be removed before removing VDD.
- If VDD is supplied and VDD_GPIO is grounded, extra current consumption can be generated on VDD.
- If the ENABLE pin is low, VDD_GPIO should also be low.
4.5.1 PCB layout design
When designing the PCB layout, pin-specific recommendations should be
followed.
The VDD_GPIO pin has the following recommendations:
- Place capacitors C5 and C6 close to the VDD_GPIO pin for good power delivery.
- Use a track that is wide enough (DCR <0.1 Ω) for VDD_GPIO routing to minimize voltage drops and unwanted power consumption due to routing losses under high current conditions.
- Connect capacitors to the same ground plane as nRF9160 (pin 103) using low impedance ground connections.
- Avoid supply routings close or adjacent to sensitive routings, such as RF.
- Use shielded PCB layers for routings whenever possible to minimize radiated noise.
- Use plenty of ground vias along supply routings to minimize unwanted voltage differences in the application PCB’s metal layers.
- A series solder bridge is recommended in the VDD routing for current consumption measurements or other diagnostic purposes.
4.6 GPIOs P0.00–P0.31
The application GPIO pins (2–4, 15, 16, 18–20, 23–26, 28–30, 35, 37–40, 42,
83, 84, 86–89, 95–97, 99, and 100) are used for interfacing and communicating
with application peripherals like sensors, Integrated Circuit (IC)s, external
memories, buttons, and LEDs.
GPIOs are powered from VDD_GPIO. They have the same voltage level as VDD_GPIO
and any unwanted noise or spurious that VDD_GPIO may contain. Therefore, it is
important to have proper noise filtering in VDD_GPIO (pin 12). It is also
important for each individual GPIO pin to meet the filtering requirements
specified for the peripherals connected to them. To avoid digital noise
generated by the GPIOs, fast transients should be avoided. It is recommended
to use the slowest possible rise times that the peripherals connected to the
GPIOs allow.
To reduce transient currents, series resistors or ferrite beads can be used on
the GPIO lines. For GPIOs, resistors in the range of 100 Ω to 1 kΩ can be
considered as they are low current digital controls. Optimal resistor values
depend mainly on the connected peripheral drive currents and communication
speed or other application-level requirements. In addition to the series
resistor, bypass capacitors in the range of a few pF can be considered. They
may help to reduce RF coupling to the GPIO lines. Unused GPIOs can be left
electrically unconnected, but it is recommended to solder them to the
application board for improved thermal and mechanical performance.
Note: Additional capacitance increases GPIO loading and noise originated
from GPIO toggling.
Note: It is not recommended to use high voltage, high drive GPIO outputs
with high frequency and high capacitance loads unless specifically needed,
because it may increase the noise level and affect the performance of the GPS
and LTE radio receivers.
4.6.1 Features
The GPIOs have user-configurable features.
The features are provided in the following list:
- Configurable output drive strength
- Internal pull-up and pull-down resistors
- Wake-up from high- or low-level triggers on all pins
- Trigger interrupt on state changes on any pin
- All pins can be used by the Programmable Peripheral Interconnect (PPI) task/event system
- One or more GPIO output can be controlled through PPI and GPIOTE channels
- All pins can be individually mapped to interface blocks for layout’s flexibility
- GPIO state changes captured on SENSE signal can be stored by LATCH register
- Support for secure and non-secure attributes for pins in conjunction with the system protection unit
For more information on GPIO feature support, see GPIO – General purpose input/output in nRF9160 Product Specification.
4.6.2 PCB layout design
When designing the PCB layout, pin-specific recommendations should be
followed.
The GPIO pins have the following recommendations:
- Place filtering series resistors close to the respective GPIO pins.
- Place capacitors close to the origin of noise and ground them to same ground plane as VSS on nRF9160.
- Avoid parallel routing of GPIOs close to sensitive RF routings due to the risk of noise decoupling from GPIO to RF routing.
- Avoid parallel routings of GPIOs close to supply or RF routings due to the risk of noise decoupling from other routings to the GPIO routings.
- Use shielded PCB layers for GPIO routings whenever possible to minimize radiated noise.
- Follow the instructions in the peripheral datasheets.
4.7 DEC0
DEC0 (pin 13) is an nRF9160-internal power management unit (PMU) output pin
for an external decoupling capacitor.
An external capacitor improves the stability of the internal supply. The
voltage level of DEC0 is approximately 2.2 V. The recommended capacitor value
is provided in Table 2: nRF9160 application component recommendations on page
14.
In the PCB layout, place C7 close to the DEC0 pin and connect the ground
capacitor to the same ground plane as nRF9160 VSS (pin 103).
4.8 nRESET
nRESET (pin 32) is a dedicated SoC reset pin. A SoC reset is generated when
the nRESET pin is pulled low and released. To ensure that the reset is issued
correctly, the reset pin should be held low for a few microseconds.
The nRESET pin has a 13 kΩ internal pull-up resistor that is always on and
connected to the nRF9160 internal voltage of 2.2 V. The nRESET pin can be
connected to an external controller or mechanical switch that is controlled by
the user. It is recommended to add a bypass capacitor and series resistor in
the range of 1 kΩ to the nRESET routing close to the nRESET pin. For more
information on pin reset, see Reset in nRF9160 Product Specification.
Note:
- External pull-up is not allowed in the nRESET pin.
- External filtering components affect the minimum pulse length.
4.9 SWD
The SWD interface provides a non-intrusive mechanism for debugging and tracing
nRF9160. It can also be used for programming the firmware and accessing
registers.
The SWD interface consists of SWDCLK (pin 33) and SWDIO (pin 34). The SWDCLK
pin provides clock signal, and SWDIO provides data. The SWDIO pin has an
internal pull-up resistor whereas the SWDCLK pin has an internal pull-down
resistor. The SWD interface’s logic high level originates from the DEC0 level,
which is approximately 2.2 V. For more information on the SWD interface, see
Debug and
trace
in nRF9160 Product Specification and nWP034 – nRF9160 Hardware Verification
Guidelines.
4.10 UICC
The Universal Integrated Circuit Card (UICC) interface is also known as the
Universal Subscriber Identity Module (USIM) or SIM interface. It consists of
SIM_RST (pin 43), SIM_DET (pin 45), SIM_CLK (pin 46), SIM_IO (pin 48), and
SIM_1V8 (pin 49).
nRF9160 supports UICC Class C interface with 1.8 V nominal voltage as
described in ETSI TS102 221. If needed, support for higher supply voltage
classes must be built with external components, including an external power
supply and level shifters towards the UICC interface of the LTE modem.
The LTE modem controls the following physical interfaces towards the UICC and
implements the transport protocol over the ISO/IEC 7816-3 interface:
- SIM_1V8 (power supply): Output from LTE modem
- SIM_CLK (clock signal): Output from LTE modem
- SIM_RST (reset signal): Output from LTE modem
- SIM_I/O (input/output serial data): Bi-directional
- SIM_DET (reserved for card detection, not in use)
4.10.1 Features
If the device has a user-accessible slot for a UICC card, ESD sensitivity
should be considered. The nRF9160internal ESD protection is intended for a 1.5
kV Human Body Model (HBM) level. External ESD/EMI filtering is recommended
between the UICC card
slot and nRF9160.
Several ESD/EMI filtering options are available. A commonly used option is a
dedicated integrated component, such as STM EMIF03-SIM02M8, TI TPD3F303, or
OnSemi CM1402. Typically, an integrated ESD filter consists of lowpass filters
and ESD diodes in a small SMD package. Another option is discrete ESD
protection which takes more space on the PCB, but can be more flexible for
certain applications and a lower-cost solution.
Discrete ESD protection can consist of the following components:
- Bypass capacitors in the range of ≤ 22 pF to SIM_RST, SIM_DET, SIM_CLK, SIM_IO, and SIM_1V8.
- A separate supply capacitor ranging from 100 nF to 220 nF connected to SIM_1V8 can be considered.
- Low capacitance type ESD diodes to SIM_RST, SIM_DET, SIM_CLK, SIM_IO, and SIM_1V8.
- Multichannel ESD diodes are commonly used and recommended.
- Some multichannel diode components incorporate EMI filtering. This type is recommended if the product integrates an LTE antenna, or an external antenna is located close to the SIM holder.
The electrical specifications for all UICC signals that should be verified in product design and in the prototyping phase are defined in ETSI TS 102 221, chapter Electrical specifications of the UICC. For more information, see nWP034 – nRF9160 Hardware Verification Guidelines.
4.10.2 PCB layout design
When designing the PCB layout, interface-specific recommendations should be
followed.
The UICC interface has the following recommendations:
- If the product integrates a GPS or LTE antenna, avoid placing the SIM holder close to the antenna due to the risk of digital noise coupling from the SIM application to the antenna.
- Place the UICC application as close to nRF9160 as possible to minimize the routing length. Long routing reduces signal integrity in the UICC interface and increases the risk of radiated noise.
- Use the same application board ground plane for the UICC application and nRF9160’s VSS to guarantee low impedance ground connection between nRF9160 and the UICC application.
- Avoid routing the UICC interface close or adjacent to sensitive RF routings, such as GPS or ANT.
- Place the ESD and EMI components or discrete components as close as possible to the UICC application’s pins SIM_RST, SIM_CLK, SIM_IO, and SIM_1V8 to optimize their performance.
- Consider test points in SIM_RST, SIM_CLK, and SIM_IO for debugging purposes.
4.11 MAGPIO
The MAGPIO interface consists of digital 1.8 V I/O pins 53–55 that can be
controlled by the LTE modem and nRF9160 application processor.
When controlled by the LTE modem, MAGPIO timing is aligned with the LTE
protocol, which enables LTE protocol synchronous control for nRF9160-external
components, such as the antenna tuner. For more information, see LTE modem RF
control external
interface
in nRF9160 Product Specification.
4.12 MIPI RF front-end
MIPI RFFE is a dedicated RF front-end component control interface.
It consists of VIO (pin 57), SCLK (pin 58), and SDATA (pin 59). VIO is a 1.8 V
supply for the MIPI controller, SCLK is the clock for the controller, and
SDATA is for the control data. The RFFE interface is aligned with the LTE
protocol, which enables LTE protocol synchronous control for nRF9160-external
components, such as an antenna tuner.
nRF9160 supports RFFE v1.1 with the following exceptions:
- SCLK is fixed rate 19.2 MHz.
- Only one RFFE component is supported at a time.
- The VIO voltage may be high at any time when nRF9160 is active, not only when external RFFE components are used.
- The capacitive load of SCLK and SDATA must not exceed 15 pF on the application board.
For noise filtering and diagnostic purposes, it is recommended to add series resistors to SCLK (R3) and SDATA (R4). In addition to the series resistor, bypass capacitors (C14, C15, and C16) in the range of few pF can be considered. They may help to reduce RF coupling to the RFFE lines. Additional capacitance increases the RFFE load and potentially deteriorates signal integrity. By default, it is not recommended to assemble capacitors C14, C15, and C16.
Note: VIO should be assumed to be high when the LTE modem is active.
Therefore, an external RFFE component should not have excessive current
leakage at VIO in any conditions. Typically, VIO consumption or leakage in
RFFE components is very low, but it is recommended to be verified from the
component datasheet. External RFFE components must withstand a situation where
VIO is high, but VDD low. Typically, this is acceptable, but some RFFE
components may be more sensitive than others.
CAUTION: The combined load of PCB routing, input load of the RFFE
component controller, and parasitic load from the application shall not exceed
15 pF at nRF9160’s SCLK or SDATA pins. Typically, this load equals narrow
transmission line length of ≤ 10 cm on the application board, but depends on
the actual PCB design.
4.12.1 PCB layout design
When designing the PCB layout, interface-specific recommendations should be
followed.
The MIPI RFFE interface has the following recommendations:
- Parasitic capacitance in routing must not exceed 15 pF at SCLK or SDATA.
- If additional filtering is needed, place capacitors C14, C15, and C16 close to the component RFFE is connected to where the noise originates from, for example, the antenna tuner.
- Avoid adjacent routings of SCLK and SDATA to noisy routings, such as RF or supply.
- Use shielded PCB layers for RFFE routings whenever possible to minimize radiated coupling.
- Follow the instructions of the RFFE peripheral datasheets.
4.13 ANT
ANT (pin 61) is a 50 Ω single-end interface for the LTE antenna for cellular
bands. To ensure good performance, antenna impedance and the characteristic
impedance of the transmission line connecting the antenna to the ANT pin must
be 50 Ω. Impedance mismatch leads to performance deterioration.
The length of the transmission line from the antenna to the ANT pin should be
kept as short as possible to minimize loss, because loss deteriorates the
transmitted and received power in nRF9160 and leads to drawbacks in power
consumption and network coverage. A maximum of 0.5 dB loss in the transmission
line is acceptable.
nRF9160 includes an ESD circuit on the ANT pin. The ESD circuit is intended
for 1.5 kV HBM level, but additional ESD protection is recommended, especially
if there are active components, such as switches or antenna tuners, in the
antenna path. For the ESD requirements, see the component datasheets.
The ANT pin is DC grounded. A matching network of a minimum of three
components is typically needed close to the antenna. The component values and
matching topology depend on the antenna application and antenna path impedance
and need to be optimized individually for each design. For more information on
the antenna interface, see nWP033 – nRF9160 Antenna and RF Interface
Guidelines.
4.13.1 PCB layout design
When designing the PCB layout, pin-specific recommendations should be
followed.
The ANT pin has the following recommendations:
- To ensure good, radiated performance, begin the design by locating the LTE antenna on the PCB.
- Ensure preliminary antenna performance on a chosen PCB location, for example, by simulation.
- When multiple antennas, for example, LTE, GPS, and Bluetooth® Low Energy are present, minimize antenna crosstalk.
- Antenna transmission line impedance should be 50 Ω. Take this into account when selecting the PCB stack-up.
- Avoid excessive capacitance in routing by opening ground layers under component pads. For example, if the routing is on the top PCB layer, open the ground plane under the ANT pad on the next metal layer.
- When opening ground planes, avoid exposing noisy routings under the ANT pad.
- Avoid long routing because it causes excessive insertion loss which deteriorates RF performance which cannot be reversed.
- Ensure continuous reference ground plane above, below, or both of the ANT routing.
- Consider adding a test connector to the antenna path for production test and diagnostic purposes.
Ensure that the test connector or solution does not deteriorate the impedance of the transmission line.
4.14 AUX
AUX (pin 64) is a 50 Ω single-end auxiliary port that can be used to loop back
the signal that is fed into the ANT pin. AUX can be used when two radios share
an antenna. For example, when using a combined GPS and LTE antenna, an
internal RF switch in nRF9160 provides the needed isolation between the GPS
and LTE paths.
AUX can be configured in software so that when the GPS receiver is on, AUX is
connected to the ANT inside the System in Package (SiP). This enables the
routing of the GPS signal from the shared LTE and GPS antenna to AUX and
through a recommended external Low-Noise Amplifier (LNA) to the GPS input. To
minimize mismatch losses, using external matching components between AUX and
LNA is recommended.
For more information on the antenna interface, see nWP033 – nRF9160 Antenna
and RF Interface
Guidelines.
For more information on configuring the AUX firmware, see nRF91 AT Commands
Reference
Guide.
4.14.1 PCB layout design
When designing the PCB layout, pin-specific recommendations should be
followed.
The AUX pin has the following recommendations:
- Antenna transmission line impedance should be 50 Ω. Take this into account when selecting the PCB stack-up.
- Avoid excessive capacitance in routing by opening ground layers under component pads. For example, if the routing is on the top PCB layer, open the ground plane under the AUX pad on the next metal layer.
- When opening ground planes, avoid exposing noisy routings under the AUX pad.
- Avoid long routing because it causes excessive insertion loss which deteriorates RF performance which cannot be reversed.
- Ensure continuous reference ground plane above, below, or both of the AUX routing.
4.15 GPS
GPS (pin 67) is a 50 Ω single-end interface for the GPS antenna.
To ensure good GPS reception performance, antenna impedance and the
characteristic impedance of the transmission line connecting the antenna to
the GPS pin must be 50 Ω. Impedance mismatch leads to reduced performance.
Loss deteriorates the received power and GPS reception of nRF9160. To minimize
loss, the length of the transmission line from the antenna to the GPS pin
should be kept as short as possible. A maximum of 0.5 dB transmission line
loss is acceptable. If an external GPS LNA is used, and it is located close to
the GPS antenna, the routing impedance and length recommendations may be
waivered.
nRF9160 includes an ESD circuit on the GPS pin. The ESD circuit is intended
for 1.5 kV HBM level, but additional ESD protection is recommended. The GPS
pin is DC grounded. For more information on the antenna interface, see nWP033
– nRF9160 Antenna and RF Interface
Guidelines.
Note: Using the GPS receiver without an external LNA and Band-Pass Filter (BPF) is not recommended.
4.15.1 PCB layout design
When designing the PCB layout, pin-specific recommendations should be
followed.
The GPS pin has the following recommendations:
- To ensure good, radiated performance, begin the design by locating the GPS antenna on the PCB.
- Ensure preliminary antenna performance on a chosen PCB location, for example, by simulation.
- When multiple antennas, for example, LTE, GPS, and Bluetooth Low Energy are present, minimize antenna crosstalk.
- Antenna transmission line impedance should be 50 Ω. Take this into account when selecting the PCB stack-up.
- Avoid excessive capacitance in routing by opening ground layers under component pads. For example, if the routing is on the top PCB layer, open the ground plane under the GPS pad on the next metal layer.
- When opening ground planes, avoid exposing noisy routings under the GPS pad.
- Avoid long routing because it causes excessive insertion loss which deteriorates RF performance which cannot be reversed.
- Ensure continuous reference ground plane above, below, or both of the GPS routing.
- Consider adding a test connector to the antenna path for production test and diagnostic purposes.
Ensure that the test connector or solution does not deteriorate the impedance of the transmission line.
4.16 COEX
The COEX interface consists of pins 91–93. It is dedicated for RF interference
avoidance towards a companion radio device, such as an external positioning
device or Bluetooth Low Energy device.
The COEX interface is powered from VDD_GPIO. To control the COEX interface,
the LTE modem must be active. When the LTE modem is not active, the COEX
interface floats. Therefore, it is mandatory to use external pull-down
resistors in the size range of 100 kΩ in the COEX interface.
The COEX pins have the following functionalities:
-
COEX0 (pin 93)
-
Can be configured for external GPS LNA control (high state) during GPS receive the same way as the %XMAGPIO command with the exception that %XMAGPIO controls only one pin. For more information, see MAGPIO configuration %XMAGPIO in nRF91 AT Commands Reference Guide.
-
COEX1 (pin 92)
-
Can be used during GPS receive to deliver GPS one pulse per second (1PPS) time mark pulse.
Note: Supported in a future release of the modem firmware. -
COEX2 (pin 91)
-
Can be used as an indicator of LTE or GPS RF activity from the modem to an external device. When COEX2 is high, the LTE or GPS RF is active, and when it is low, the LTE or GPS RF is inactive.
-
Can be used as a “BLE nGrant”. This means that Bluetooth Low Energy should not transmit when COEX2 is high and Bluetooth Low Energy can transmit when COEX2 is low.
-
Can be used with %XRFTEST AT commands. For more information, see Production test features in nRF91 AT Commands Reference Guide.
4.16.1 Features
The COEX pins are powered from VDD_GPIO (pin 12). They have the same voltage
level as VDD_GPIO and any unwanted noise or spurious that VDD_GPIO may
contain. Therefore, proper noise filtering in VDD_GPIO is important. It is
also important for each individual COEX pin to meet the filtering requirements
specified for the peripherals connected to them.
To reduce transient currents, series resistors or ferrite beads can be used in
the COEX lines. For low current, digital control type of COEX routings,
resistor values in the range of 100 Ω to 1 kΩ can be considered. However, the
optimal resistor values depend mainly on the connected peripheral drive
currents and communication speed required by the peripherals.
In addition to the series resistor, bypass capacitors in the range of few pF
can be considered. They may help to reduce RF coupling to the COEX lines.
Unused COEX pins can be left unconnected electrically, but it is recommended
to connect them to the application board for improved thermal and mechanical
performance. For more information on the COEX interface configurations, see
nRF9160 Product
Specification.
Note: Additional capacitance increases COEX loading and noise originated from COEX toggling.
4.16.2 PCB layout design
When designing the PCB layout, interface-specific recommendations should be
followed.
The COEX interface has the following recommendations:
- Place filtering series resistors close to the respective COEX pins.
- Place capacitors close to the origin of noise.
- Ground capacitors to the same ground plane as VSS (pin 103).
- Avoid routing COEX close to sensitive routings due to the risk of noise decoupling from COEX.
- Avoid routing COEX close to supply or RF routings due to the risk of noise decoupling to COEX.
- Use shielded PCB layers for GPIO routings whenever possible to minimize radiated noise.
- Follow the instructions in the peripheral datasheets.
4.17 Reserved
Pins 10, 51, 70, 71, 73, and 104–127 are reserved for Nordic’s internal
diagnostic purposes.
It is recommended to connect the Reserved pins to the application board
mechanically and thermally, but to keep them electrically unconnected. To
facilitate a simpler or more economical stencil design, Reserved pins 104–127
can be left electrically, mechanically, and thermally unconnected with no
stencil openings for them.
Hardware design
The design of an end product is often driven by small form factor and
attractive appearance. However, to achieve a product with solid performance,
several design factors must be considered.
Some of those design factors conflict with the small form factor target.
Typically, this means a compromise in the design that may affect the
performance or appearance of the end product.
When a preliminary schematic of the device is ready, designing the PCB can
begin. Layout design is typically iterative and involves trade-offs. The first
hardware design rarely ends up being the massproduced version.
To minimize the number of hardware design rounds, cost, and time, the selected
essential design factors that have a major impact on the end product’s RF
performance are discussed here.
5.1 Component placement
It is recommended to categorize and prioritize connections between nRF9160 and
application components according to how critical they are.
For nRF9160’s performance, RF routings are the most critical due to the
mandatory impedance control and noticeable impact that they have on the user
experience. Power supply routings are also important because insufficient
power supply design causes nRF9160 to work improperly. In addition, the SIM
and MIPI RFFE interfaces are sensitive and should be prioritized in the layout
work.
It is also recommended to categorize application components according to which
ones can be adjacent to one another on the PCB. For example, sensitive
antennas and noisy DC converters or LEDs should never be adjacent to each
other on a PCB. Two antennas, such as GPS and LTE, should never be adjacent to
each other on a PCB because of the risk of mutual load effect between two
nearby radiators. The load effect can noticeably deteriorate antenna
efficiency and radiation pattern and have a major impact on the
overall performance of the end product.
Some components, such as the LTE antenna and SIM holder, should be close to
nRF9160 to minimize the negative impact of a long PCB routing, but not near
each other. These components should not be too far from nRF9160, but their
mutual distance should be maximized. It is recommended to place these
components on the opposite sides of the PCB if possible.
Based on connections and component categorization, layout and component
placement mockup can be started. Start the layout work from the most critical
routings. Aim to have at least one dedicated PCB metal layer as a common
ground plane for the entire PCB, keeping it as intact as possible. This metal
layer also acts as the main thermal dissipation power relief path for nRF9160
and other active components on the application board.
A small form factor PCB sets constraints for component placement, especially
for the antenna and its ground layer. Optimal placement for antennas is
important and helps guarantee radiated performance and a good user experience
for the end product. Therefore, it is recommended to estimate with 3D
simulation tools the impact of different antenna locations and grounding on
the PCB. Antenna design and simulation services are provided by various design
houses globally.
Antenna vendors often provide design and measurement services, but typically
they are meant only for their own products. If the end product includes
antennas from more than one vendor, it is important to make sure that all
antennas are verified to perform as expected simultaneously on a small form
factor PCB or in the end product.
5.2 External flash memory requirements
If you want to perform a full modem firmware upgrade, an external flash memory
with a minimum of 4 MB free space is required.
You can find more information on updating modem firmware at the following
links:
5.3 Antennas
If a small form factor device integrates antennas with noticeable performance
requirements, for example, GPS or LTE, the antenna related design should be
prioritized.
The key requirement in antenna design is that all antennas fulfill their
performance targets in the actual use cases of the end product. The efficiency
target for the LTE and GPS antennas should be a minimum of 50%. For the best
possible GPS performance, the recommended efficiency is a minimum of 75%.
5.3.1 Troubleshooting
This section describes typical performance related issues in the end product’s
antenna design and ways to reduce them.
The placement of the antenna on the PCB and ground plane prevents from
achieving good enough antenna radiation performance.
Follow the antenna vendors recommendations for placing the antenna on the PCB
and ground plane.
Verify the antenna radiation pattern and efficiency in an anechoic chamber to
match the datasheet.
RF path routing loss between antenna and nRF9160 is too high.
Verify 50 Ω impedance-controlled routing between the antenna and nRF9160.
Target less than 0.5 dB for resistive loss between the antenna and nRF9160.
Note: GPS is recommended to be used with an external LNA. This means that resistive routing loss between the GPS LNA and nRF9160 is not highly critical. However, it is highly critical to avoid noise coupling from adjacent routings or components to GPS signal routing between the GPS antenna and nRF9160.
Mechanics, casing, battery, or wires deteriorate antenna performance.
Co-design the mechanics to match the PCB and antenna design.
Sharing a small PCB between several antennas, for example, GPS and LTE, causes
mutual loading between the antennas.
Verify that the antennas do not cause mutual loading, for example, with
passive antenna measurements in an anechoic chamber. Terminating an unused
antenna, for example the LTE antenna during GPS, may have a noticeable impact
on the mutual loading effect between the antennas. To minimize the load
effect, the LTE antenna can be terminated through the AUX port (pin 64) to 50
Ω load during GPS.
Active components on the PCB cause wideband noise coupling to the
antennas.
Verify that during reception, especially GPS, active components on the PCB do
not radiate noise to the GPS antenna. For example, DC converters and LEDs are
typical sources of radiating wideband noise. The RSSI scan testing method can
be used. For more information, see nWP034 – nRF9160 Hardware Verification
Guidelines.
The orientation of the end product in a typical use case is less than
optimal for the antenna radiation pattern.
Consider in the design phase what the orientation of the end product is going
to be in a typical use case.
Consider in the design phase the type of the GPS antenna, for example,
omnidirectional or linear and directive or Right Hand Circular Polarization
(RHCP).
Nearby objects deteriorate antenna performance.
Instruct the end user to use the device in the manner it is designed for. For
example, inform the user not to expect the best possible radio performance
when the device is used inside a building, on a metal surface, or on their
body.
GPS signal environment is more challenging than assumed in the design
phase.
Instruct the end user to use the device in the manner it is designed for. The
GPS signal type must be line-of-sight (LOS), which is rarely available in
places like city centers with tall buildings nearby. The issue is even more
severe in the polar regions because the GPS system is designed to perform the
best in the equatorial regions.
5.4 nRF9160 module
The main principle in placing the nRF9160 module is to optimize the highest
priority routings as described in Component placement on page 27.
Other important aspects are to achieve good thermal and mechanical contact to
the application board and to avoid placing nRF9160 close to noisy components
on the application board, such as DC converters or LEDs.
5.5 Thermal design
Good thermal design on the application board is essential for maximizing the
performance and battery life of nRF9160. Poor thermal design causes nRF9160’s
built-in thermal protection to more easily trigger, preventing nRF9160 from
transmitting and receiving LTE and GPS data.
The maximum power consumption and operating temperature of nRF9160 and the
JEDEC standardized thermal coefficients are shown in the following table.
Parameter | Value |
---|---|
Power consumption (maximum heat power dissipation) | 1480 mW |
Maximum operating temperature | 85°C |
RthetaJA (Module-to-Ambient) | 23°C/W |
RThetaJB (Module-to-Board) | 6°C/W |
RThetaJC (Module-to-Case) | 1°C/W |
Maximum allowed Tc (Module case temperature) | 85°C |
Maximum Allowed Tj (Worst case of module components) | 85°C |
Table 3: Thermal characteristics of nRF9160
Note: Thermal resistance (JA, JB, and JC) is measured in still air conditions with the module mounted on 72 mm x 46 mm x 1.2mm 6-layer PCB with high copper coverage on all metal layers.
5.6 PCB stack-up
Choosing the PCB stack-up should be aligned with the end product’s PCB
requirements.
For nRF9160, the following targets should be considered:
- Dedicate one metal layer that is as intact as possible for the common ground layer.
- Consider the need for 50 Ω RF routings. Sometimes to achieve 50 Ω routing requires the adjacent metal layer to be opened which increases the risk of exposing RF routing to noisy routings.
- Avoid crossing 50 Ω RF routings on the application board. If it cannot be avoided, ensure that their ground planes remain continuous.
- Avoid using through vias in RF routings if they cause a parallel stub to the routing or are not 50 Ω.
- Consider good thermal design and aim to use metal filled vias due to their better thermal conductivity especially close to nRF9160.
Glossary
Band-Pass Filter (BPF)
An electronic device or circuit that passes frequencies within a certain range
and rejects frequencies outside that range.
DC
Direct Current
Device Firmware Update (DFU)
A mechanism for upgrading the firmware of a device.
Electrostatic Discharge (ESD)
A sudden discharge of electric current between two electrically charged
objects.
Global Positioning System (GPS)
A satellite-based radio navigation system that provides its users with
accurate location and time information over the globe.
General-Purpose Input/Output (GPIO)
A digital signal pin that can be used as input, output, or both. It is
uncommitted and can be controlled by the user at runtime.
GPIOTE
General-Purpose Input/Output Tasks and Events
Human Body Model (HBM)
Simulates a charged person discharging to ground through a circuit.
Integrated Circuit (IC)
A semiconductor chip consisting of fabricated transistors, resistors, and
capacitors.
Low-Noise Amplifier (LNA)
In a radio receiving system, an electronic amplifier that amplifies a very
low-power signal without significantly degrading its signal-to-noise ratio.
MIPI RF Front-End Control Interface (RFFE)
A dedicated control interface for the RF front-end subsystem. MIPI
Alliance
Power Amplifier (PA)
A device used to increase the transmit power level of a radio signal.
Printed Circuit Board (PCB)
A board that connects electronic components.
Programmable Peripheral Interconnect (PPI)
Enables peripherals to interact autonomously with each other using tasks and
events independent of the CPU.
Right Hand Circular Polarization (RHCP)
Circular polarization in which the electric field vector rotates in a right-
hand sense with respect to the direction of propagation.
Serial Wire Debug (SWD)
A standard two-wire interface for programming and debugging Arm® CPUs.
Subscriber Identity Module (SIM)
A card used in User Equipment (UE) containing data for subscriber
identification.
System in Package (SiP)
Several integrated circuits, often from different technologies, enclosed in a
single module that performs as a system or subsystem.
System on Chip (SoC)
A microchip that integrates all the necessary electronic circuits and
components of a computer or other electronic systems on a single integrated
circuit.
Universal Integrated Circuit Card (UICC)
A new generation SIM used in UE for ensuring the integrity and security of
personal data.
Universal Subscriber Identity Module (USIM)
A card used in UE containing data for subscriber identification.
User Equipment (UE)
Any device used by an end-user to communicate. The UE consists of the Mobile
Equipment (ME) and the Universal Integrated Circuit Card (UICC).
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References
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