HOPERF CMT453x Series Chips User Guide

HOPERF CMT453x Series Chips

Product Information

• Product Name: CMT453x Series Bluetooth Chips
• Product Version: Rev 1.4
• Design Guide: Design Guide for Hardware of CMT453x Series Chips
• Manufacturer: Hoperf
• Website: www.hoperf.com.

Product Usage Instructions

Schematic Design Guide:
The schematic design guide provides detailed information on the hardware design experiences of the CMT453x series Bluetooth chips. It includes specifications for chip hardware design, selection of important components, and cautions for PCB layout.

Power Supply:

1. Power supply:
   • When the external power supply voltage is 1.8V-3.6V, it can be directly connected to the chip VCC.
   • VCCRF, with a maximum supply of 3.6V, is recommended to be connected to the VCC pin in parallel.
   • Ensure that the chip GND pin is connected to the square bonding pad at the bottom of the chip to create a GND network. Refer to Chapter 3.3 for more details.
2. Differences between two power supply modes:****
   Mode| Parameters| BOM Difference| Active Power Consumption| Power Consumption in Sleep Mode| RFTX Power Consumption| RFRX Power Consumption| RFRX Sensitivity| RFRX Maximum Power
   ---|---|---|---|---|---|---|---|---
   DCDC power supply mode| 4.7uh inductor| Not required| 1.8 mA| 1.6 uA| 4 mA| 3.8 mA| -96 dBm| +6 dBm
   LDO power supply mode| 4.7uh inductor| Required| 3.8 mA| 1.6 uA| 8 mA| 7.8 mA| -96 dBm| +6 dBm

Reference Schematic Designs:

3. Reference schematic design for DCDC power supply mode:
4. Reference schematic design for LDO power supply mode:
5. Reference minimum system BOM table:
   Item| Part Name| Description
   ---|---|---
   0001| CAP0402,105| CAP,CER,16V,1UF,X7R,10%,0402
   0002| CAP0402,104| CAP,CER,16V,0.1UF,X7R,10%,0402
   0003| CAP0603,2.2uF| CAP,CER,10V,2.2UF,X7R,10%,0603
   0004| CAP0603,10uF| CAP,CER,10V,10UF,X7R,10%,0603
   0005| CAP0402,1.2PF| CAP,CER,50V,1.2PF,COG,5%,0402
   0006| CAP0402,12PF| CAP,CER,50V,12PF,COG,5%,0402
   0007| CAP0402,100PF| CAP,CER,50V,100PF,COG,5%,0402
   008| CMT4531_QFN32| IC,CMT4531,QFN32,32PIN
   009| XTAL_32MHz| XTAL,32MHz,8PF,10PPM,SMD_1612,4PIN,-4085(NDK,
   NX1612A-32MHz-STD-CIS-3)
   0010| INDUCTOR_2.2UH| L3
   0011| INDUCTOR_1.3nH| L6
   0012| INDUCTOR_1nH| L8
   0013| ESD Protection| TVS1, TVS2
6. Reference schematic design for external crystal:
7. Reference schematic design for reset circuit:
8. Reference schematic design for microphone circuit:
9. Reference Schematic design for Infrared Transmitter Circuit:

Overview
This document is the summary of hardware design experiences of CMT453x series Bluetooth chips. It is the detailed specifications for chip hardware design, selection of some important components and cautions for PCB Layout.

Schematic design guide

Power supply

1. When the external power supply voltage is 1.8V～3.6V, it can be directly connected to chip VCC.
2. VCCRF, from which the maximum supply is 3.6V, is recommended to be connected to VCC pin in parallel.
3. Note the chip GND pin is at the bottom of the chip, and be sure to connect the square bonding pad at the bottom of the chip to GND network. See Chapter 3.3 for details.

Differences between two power supply modes
Two power supply modes are available for chips, and the main differences between the two modes are below:

Mode

Parameters

| DCDC power supply mode| LDO power supply mode
---|---|---
BOM difference| 4.7uh inductor required| 4.7uh inductor not required
Active power consumption| 1.8 mA| 3.8 mA
Power consumption in Sleep mode| 1.6 uA| 1.6 uA
RFTX power consumption| 4 mA| 8 mA
RFRX power consumption| 3.8 mA| 7.8 mA
RFRX sensitivity| -96 dBm| -96 dBm
RFRX maximum power| +6 dBm| +6 dBm

Reference schematic design for DCDC power supply mode

Reference schematic design for LDO power supply mode

Reference minimum system BOM table

Item| Part Name| Description| REV| QTY| Reference
---|---|---|---|---|---
0001| CAP0402,105| CAP,CER,16V,1UF,X7R,10%,0402|  | 4| C4,C20,C23,C30
0002| CAP0402,104| CAP,CER,16V,0.1UF,X7R,10%,0402|  | 1| C19
0003| CAP0603,2.2uF| CAP,CER,10V,2.2UF,X7R,10%,0603|  | 1| C9
0004| CAP0603,10uF| CAP,CER,10V,10UF,X7R,10%,0603|  | 1| C18
0005| CAP0402,1.2PF| CAP,CER,50V,1.2PF,COG,5%,0402|  | 1| C32
0006| CAP0402,12PF| CAP,CER,50V,12PF,COG,5%,0402|  | 2| C28,C29
0007| CAP0402,100PF| CAP,CER,50V,100PF,COG,5%,0402|  | 1| C33
008| CMT4531_QFN32| IC,CMT4531,QFN32,32PIN|  | 1| U1
009| XTAL_32MHz| XTAL,32MHz,8PF,10PPM,SMD_1612,4PIN,-40℃～85℃(NDK, NX1612A- 32MHz-STD-CIS-3)|  | 1| Y2
0010| INDUCTOR_2.2UH| INDUCTOR, 2.2UH,±20%, power inductor, RDC(direct-current

resistance) 250mΩ, Heat Rating Current 800mA, 0805, (MPH201210S4R7MT, Sunlord)

|  | 1| L3
---|---|---|---|---|---
0011| INDUCTOR_1.3nH| INDUCTOR, 1.3nH,±0.3nH, high-frequency inductor, RDC (direct-current resistance) 100mΩ, Rated Current 300mA, 0402, (SDCL1005C1N3STDF, Sunlord)|  | 1| L6
0012| INDUCTOR_1nH| INDUCTOR, 1nH,±0.3nH, high-frequency inductor, RDC(direct- current resistance) 100mΩ, Rated Current 300mA, 0402, (SDCL1005C1N0STDF, Sunlord)|  | 1| L8
0013| ESD Protection| IEC61000-4-2 (ESD) ±20kV (air)， ±20kV (contact) Working voltage: 5V ；Ultra Low Capacitance：0.3pF

XE2XUC5VB DFN1006-2L

|  | 2| TVS1 TVS2

Reference schematic design for external crystal

Reference schematic design for reset circuit

Reference schematic design for microphone circuit

Reference Schematic design for Infrared Transmitter Circuit

Reference Design for Conduction/Radiation Certification (CE/FCC) test
The circuit below has a better harmonic suppression performance compared with the default design introduced in sections 1.3 and 1.4.

Specifications on chip pins in the schematic

Power supply pins

• PIN24(VDCDC) is the power supply pin receiving internal DCDC generated voltage, its typical voltage is 1.15V, it needs to be connected with a 1uF decoupling capacitor, and a 2.2uH power inductor needs to be provided in series between PIN24(VDCDC) pin and PIN23(SWITCH).
• PIN27(VDCDCRF) is the internal RF power supply pin receiving internal DCDC-generated voltage and can be directly connected to PIN24(VDCDC), its typical voltage is 1.15V and it needs to be connected with a 1uF decoupling capacitor.
• PIN28(VCCRF) is an external power supply pin, that needs to be connected with a 1uF decoupling capacitor, and its external voltage range is 1.8V～3.6 V.
• PIN22(VCC) is an external power supply pin, that needs to be connected with 0.1uF and 10uF decoupling capacitors, and its external voltage range is1.8V～3.6V。
• PIN8(VDD_FLASH) is the internal FLASH power supply pin, which needs to be connected only with 2.2uF decoupling capacitors without an external power supply.

RF pins

• PIN25(RFIOP) is RF pin.
• PIIN26(VDD_PA) receives the bias voltage with a range of 0.9V～1.7V generated by internal RF_PA, depending on the internal register configuration, the transmit power is different, and the bias voltage generated is different.

Crystal oscillator pins

• PIN29(XO32MM) and PIN30(XO32MP) are Bluetooth reference clock pins and need to be connected with 32MHz crystals. As the Bluetooth requirement for frequency deviation is high, the frequency deviation of the crystal oscillators should be ≤±10ppm. Note that external 32MHz crystals must be provided for using the Bluetooth function.
• PIN9(XO32KP_IN) and PIN10(XO32KM_OUT) are low-frequency reference clock pins, can also be used as general-purpose IO interfaces and need to be connected with 32.768KHz crystals when they are used as clock pins.

Debug pins

• PIN5(PA4/SWDCLK) and PIN6(PA5/SWDIO) are SWD pins and can also be used as general-purpose IO interfaces. When they are used as SWD pins, they can be used to download applications.
• PIN16(PB6/TX) and PIN17(PB7/RX) are UART serial port pins, and can also be used as general-purpose IO interfaces. They can be used for print when being used as serial port pins.

AMIC audio pins

• PIN20(PB11/AMIC_N) and PIN21(PB13/AMIC_P) are MIC input pins supporting single-ended input and differential input with adjustable gain.
• PIN19(PB12/AMIC_BIAS) is the pin for outputting MIC bias voltage, it outputs adjustable MICBIAS voltage with a range of 1.6～2.3V and a typical voltage of 2V.

IO interface

• For the specific definition of IO interface, see CMT453x Datasheet

Design specifications on PCB Layout

Requirements for RFIOP wiring design

• In order to ensure minimum loss, RF routing should be as short as possible, components should be as compact as possible, and RF routing should be as straight as possible and should not be right angle. The routing width and the space between the route and the peripheral GND are equivalent to the recommended value of 0.5mm. As PCB material influences the RF routing impedance, the routing width and the space between the route and the peripheral GND can be adjusted properly to ensure RF routing impedance is 50Ω.
• The wires around RF should ideally be filled with GND metal and the resulting section on the top and bottom layers should be connected with as many vias as possible.
• The zone around the antenna front and back must be separated from other routes, to ensure the space between GND and the antenna is 3mm or above and no metal component is in the space.
• Normally, the antenna length is about 30mm, equivalent to 1/4 of the Bluetooth signal wavelength.
• In order to enhance ESD protection capacity, be sure to coat the antenna surface with a solder mask rather than exposing it to the outside, It’s better to add another silkscreen layer on the top of the antenna.
• Considering that the ESD in the production line of the PCB is not well controlled during the production period, it is required to add a TVS component to the antenna port for protection, the value of the TVS diode capacitance should be as low as possible. For products within a distance of 10m, the TVS component can be replaced with a 0-ohm resistor to improve ESD protection capability. The position of the TVS component or 0-ohm resistance is shown in the figure below.

Requirements for routing of 32MHz crystal oscillator

• The two crystal oscillator routes should be as short as possible and as equivalent in length as possible, with the areas around them be filled with GND metal.
• Try not to route wires under the crystal oscillator, especially the VDCDCRF wires cannot be routed from below, as the DC voltage generated by Bluetooth broadcast affects the stability of the crystal oscillator frequency.

Requirements for routing of chip grounding

• The 32 pins of this chip do not have GND, and its GND is at the bottom of the chip.
• The chip packaging center is required to be cladded by a square copper sheet. The space between the copper sheet and the chip pin should be ≥0.3mm and ≤0.5mm, connect the copper sheet with GND via 9 holes. The hole may be 0.5mm/0.3mm. The holes should not be too large to avoid tin leaking and consequent insufficient solder.

Requirements for power supply routing

• The power supply wire for the chip should be as thick and short as possible, with the decoupling capacitor as close as possible to the chip.
• If two decoupling capacitors with different capacities are used, the smaller one should be closer to the chip than the larger one.

Requirements for AMIC audio routing

• PB11/AMIC_N and PB13/AMIC_P support single-ended input and differential input, and their routes should be differential type. The differential wires should be as short and equivalent in spacing as possible, with proper shielding by ground wire to avoid other signal interference.
• The inside of their audio module should be grounded first and then they are connected with the peripheral ground to avoid the interference from ground wire.

Version History

1.4, and update the BOM table in section 1.5.

Notice

Liability Disclaimer
Shenzhen Hope Microelectronics Co., Ltd reserves the right to make changes without further notice to the product to improve reliability, function or design. Shenzhen Hope Microelectronics Co., Ltd does not assume any liability arising out of the application or use of any product or circuits described herein.

Life Support Applications
Shenzhen Hope Microelectronics Co., Ltd’s products are not designed for use in life support appliances, devices, or systems where malfunction of these products can reasonably be expected to result in personal injury. Shenzhen Hope Microelectronics Co., Ltd customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Shenzhen Hope Microelectronics Co., Ltd for any damages resulting from such improper use or sale.

Contact Information

Shenzhen Hope Microelectronics Co., Ltd.

• Address: 30th floor of 8th Building, C Zone, Vanke Cloud City, Xili Sub-district, Nanshan, Shenzhen, GD, P.R. China
• Tel: +86-755-82973805
• Post Code: 518055
• Email: sales@hoperf.com.
• Website: www.hoperf.com.

References

• HOPERF - Reliable original manufacturer of IoT key components
• HOPERF - Reliable original manufacturer of IoT key components

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