ALLEGRO APEK80905KNB-01 APM80905 Evaluation Board User Guide
- June 13, 2024
- ALLEGRO
Table of Contents
ALLEGRO APEK80905KNB-01 APM80905 Evaluation Board
DESCRIPTION
The APM80905 Evaluation Board is designed to help system designers evaluate the operation and performance of the APM80905 synchronous buck LED driver ClearPower module. The APM80905 Evaluation Board can support various length strings of LEDs, including IR LEDs, and the output current can be configured by changing the value of a sense resistor.
FEATURES
- APM80905 Synchronous buck LED driver module.
- Test points for applying enable, PWM and analog dimming inputs.
- PWM Monitor with user-selectable TMAX and DMAX configuration for safety when powering IR LEDs.
- Active low fault flag output.
- Banana jacks for input and output power connections.
Table 1: APM80905 Evaluation Board Configurations
| Configuration Name | Part Number | Output Current (A) |
|---|---|---|
| APM80905 Evaluation Board | APEK80905KNB-01 | 1 |
Table 2: General Specifications
| Specification | Min | Nom | Max | Units |
|---|---|---|---|---|
| Input Operating Voltage | 4.5 | – | 36 | V |
| Output Current [1] | – | 1 | – | A |
| Switching Frequency | – | 2.1 | – | MHz |
| PWM Input Logic High Threshold | – | – | 1.2 | V |
| PWM Input Logic LowThreshold | 0.6 | – | – | V |
| En Input Logic High | – | 1.2 | – | V |
| EN Input Logic Low | – | – | 1.0 | V |
| ADIM Input Range | 0.62 | – | 1.75 | V |
USING THE EVALUATION BOARD
This section provides an overview of the connections and configuration options
of the APM80905 Evaluation Board. Each group of connections highlighted in
Figure 2 has a detail section below. The default jumper positions are
highlighted in green. The APM80905 datasheet contains detailed information on
the use and functionality of each pin. The datasheet should be consulted for
more detailed information than is contained in this user guide.
Power Input
Connect a power supply using banana plugs or clip leads to the left side of
the Evaluation Board using the VIN and GND connections.
Power Output
Connect one or more high power LEDs using banana plugs or clip leads to the
right side of the Evaluation Board using the LED+ and LED– connections. The
number of LEDs that can be powered is limited by the input voltage. The
APM80905 is a buck converter, so the input voltage must exceed the output
voltage for proper operation.
Output Current
The APM80905 Evaluation Board is configured for a 1 A output but can achieve
up to a 4 A output current by changing the value of the sense resistor, R10.
If an output current other than 1 A is desired, see the datasheet for details
on selecting the appropriate sense resistor.
Accurate Enable
The APM80905 Evaluation Board is set up with a 10 kΩ resistor from Vin to the
Enable pin, EN, when the Enable jumper is installed. Optionally, R2 may be
installed to complete a voltage divider on the EN pin which will allow the
APM80905 to start up and shut down at a set input voltage. If this behavior is
desired, consult the APM80905 datasheet for more details.
Analog Dimming
Analog dimming to reduce the regulated output current level is achievable by
applying a voltage between 0.62 V and 1.3 V to the ADIM test point. If analog
dimming is desired, consult the APM80905 datasheet for more details on the
setup and limitations of this function.
Device Configuration
The APM80905 Evaluation Board has three configuration jumpers. The DMAX and
TMAX jumpers must be configured prior to power-on.
Table 3: APM80905 Jumper Descriptions
| Jumper | Name | Description |
|---|---|---|
| J1 | Enable | Install jumper to tie EN pin to VIN and enable the APM80905. |
Uninstall to control enable using an external signal connected at the EN/UV
test point.
J2| DMAX| Install this jumper in the desired location for the maximum duty
cycle limit. Install in the high position for 10% or 20% or install in the low
position for 30% or 50% duty cycle. See Table 4 for more details on setting DMAX and TMAX.
J3| TMAX| Install this jumper in the desired location for maximum PWM on-time limit. Install in the high position for a 0.5 millisecond limit or install in the low position for a 2 millisecond maximum PWM on-time limit. See Table 4 for more details on setting DMAX and TMAX.
Startup Procedure
To begin using the APM80905 Evaluation Board, follow the instructions below
and refer to the diagram in Figure 2 or the test point connections outlined in
Table 5.
- Ensure the two jumpers for DMAX/TMAX are in the Low/High positions respectively for initial testing.
- Connect an LED load to the regulated output connections of the APM80905 Evaluation Board. The load should be a string of one or more LEDs capable of handling 1 A of current.
- Ensure the Enable jumper J1 is installed or leave open and apply an external enable signal to the EN/UV test point.
- If using ADIM, apply a DC voltage to the ADIM test point between 0.62 V and 1.3 V.
- Apply an external PWM signal to the PWM test point. The initial settings of the PWM signal should be a pulse wave with a frequency of 400 Hz, a duty cycle of 10%, and amplitude levels of 0 V and 2.5 V.
- Apply an input voltage across the Power Input terminals that is 3 V higher than the expected forward voltage drop of the LED string on the output. Do not exceed 36 V on the Power Input connections. To ensure desirable startup behavior the input power source should be able to supply twice the regulated output current level (1 A on the standard APM80905 Evaluation Board).
NOTE: The DMAX and TMAX jumper positions were selected for quick start up and evaluation. Once initial board operation has been achieved try different jumper configurations according to those in Table 4, combined with different PWM duty cycle limits. To obtain specific DMAX and TMAX limits, the resistor values associated with each pin can be changed. See the datasheet for detailed instructions on setting the DMAX.
Table 4: APM80905 DMAX/TMAX Settings
| DMAX | DMAX (%) | TMAX | TMAX (ms) |
|---|---|---|---|
| High | 10 | Low | 0.5 |
| Low | 20 | Low | 0.5 |
| High | 30 | High | 2.0 |
| Low | 40 | High | 2.0 |
Table 5: APM80905 Test Point Description
| Test Point | Description |
|---|---|
| VIN | Positive terminal for input voltage connection or sensing. |
| GND | Negative terminal for input voltage connection or sensing. |
| LED+ | Positive terminal for the output current to the LED load. |
| LED– | Negative terminal for the output current to the LED load. |
| EN/UV | Enable pin voltage input. Leave Enable Jumper, J1, open if applying an |
external signal on the EN/UV test point.
PWM| PWM control input. Connect an appropriate pulsed signal to this test
point to switch output current on/off. Avoid violating the DMAX and TMAX
limitations to prevent faults.
ADIM| Analog dimming control input. Apply an external voltage between 0.62 V
and 1.3 V to achieve between 20% and 90% LED dimming. The ADIM pin is pulled
high through a 100 kΩ resistor, R4, and can be left open if ADIM is not used.
FFn| The fault pin is asserted low when a fault is detected. Monitor this test
point for faults.
EVALUATION BOARD PERFORMANCE DATA
SCHEMATIC
BILL OF MATERIALS
Table 6: APEK80905KNB-01 Version Evaluation Board Bill of Materials
ELECTRICAL COMPONENTS
Designator| Quantity| Description| Manufacturer|
Manufacturer Part Number
C1| 1| Capacitor, Electrolytic, 47 uF, 50 V, 8 mm| Nichicon| UUX1H470MNL6GS
C2| 1| CAP CER 4.7 µF 50 V X5R 0805| Murata| GRM21BR61H475KE51L
C3| 1| CAP CER 0.1 µF 50 V X5R 0402| Murata| GRM155R61H104KE19D
C7| 1| CAP CER 2.2 µF 16V X5R 0402| Murata| GRM155R61C225KE11D
C6| 1| CAP CER 0.47 µF 50V X5R 0603| Murata| GRM188R61H474KA12D
L1| 1| Inductor, 3.3 uH| CoilCraft| XAL5030-332ME
R1, R11| 2| Resistor, 10.0 kΩ, 1/16 W, 1%, 0402| Yaego| AC0402FR-0710KL
R3| 1| Resistor, 0 Ω, 1/16 W, Jumper, 0402| Yaego| RC0402FR-070RL
R4| 1| Resistor, 100 kΩ, 1/16 W, 1%, 0402| Yaego| RC0402FR-13100KL
R5| 1| Resistor, 32.4 kΩ, 1/16 W, 1%, 0402| Yaego| RC0402FR-0732K4L
R6| 1| Resistor, 23.2 kΩ, 1/16 W, 1%, 0402| Yaego| RC0402FR-0723K2L
R7| 1| Resistor, 61.9 kΩ, 1/16 W, 1%, 0402| Yaego| RC0402FR-0761K9L
R8, R9| 2| Resistor, 17.4 kΩ, 1/16 W, 1%, 0402| Yaego| RC0402FR-0717K4L
R10| 1| Resistor, 0.2 Ω, 1/2 W, 1%, 1206| Panasonic| ERJ-8BSFR20V
U1| 1| APM80905 in MIS package| Allegro MicroSystems| APM80905KNBATR
OTHER COMPONENTS
Designator| Quantity| Description| Manufacturer|
Manufacturer Part Number
VIN| 1| Banana Jack- Non-Insulated .218″ Length| Keystone Electronics| 575-4
LED+| 1| Banana Jack- Non-Insulated .218″ Length| Keystone Electronics| 575-4
LED-| 1| Banana Jack- Non-Insulated .218″ Length| Keystone Electronics| 575-4
GND| 1| Banana Jack- Non-Insulated .218″ Length| Keystone Electronics| 575-4
GND1, GND2| 2| Ground Bar, 18 AWG Bus Bar, 12 mm Body| N/A| N/A
J1| 1| CONN HEADER VERT 2POS 2.54MM| Wurth Electronics| 61300211121
J2, J3| 2| CONN HEADER VERT 3POS 2.54MM| Wurth Electronics| 61300311121
MH1, MH2, MH3, MH4| 4| M3 sized mounting hole| N/A| N/A
MS1, MS2, MS3, MS4| 4| PAN HEAD SCREW_M3 X 8MM CROSS SL| Wurth Electronics|
97790803111
SO1, SO2, SO3, SO4| 4| Standoffs & Spacers 5.0 HEX 15.0 mm NYLON| Keystone
Electronics| 25512
VIN, LED+| 2| Test Point, Red, Through Hole Mount, 1.6 mm| Keystone
Electronics| 5010
GND, LED-| 2| Test Point, Black, Through Hole Mount, 1.6 mm| Keystone
Electronics| 5011
EN/UV, PWM, ADIM, FFn| 4| Test Point, Yellow, Through Hole Mount, 1.6 mm|
Keystone Electronics| 5014
PCB| 1| APM80905 Customer Evaluation Board| Allegro MicroSystems|
NOT FITTED
C4| 0| Optional Multi-Layer Ceramic Capacitor| Murata| GRM155R61C225KE11D
C5| 0| Optional Multi-Layer Ceramic Capacitor| Murata| GCM21BR71H474KA55L
R2| 0| Optional Resistor, 0402| Yaego| AC0402FR-0710KL
PCB LAYOUT
RELATED LINKS:https://www.allegromicro.com
APPLICATION SUPPORT:https://www.allegromicro.com
Revision History
| Number | Date | Description |
|---|---|---|
| – | July 26, 2023 | Initial release |
Copyright 2023, Allegro MicroSystems.
Allegro MicroSystems reserves the right to make, from time to time, such
departures from the detail specifications as may be required to permit
improvements in the performance, reliability, or manufacturability of its
products. Before placing an order, the user is cautioned to verify that the
information being relied upon is current. Allegro’s products are not to be
used in any devices or systems, including but not limited to life support
devices or systems, in which a failure of Allegro’s product can reasonably be
expected to cause bodily harm. The information included herein is believed to
be accurate and reliable. However, Allegro MicroSystems assumes no
responsibility for its use; nor for any infringement of patents or other
rights of third parties which may result from its use. Copies of this document
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Allegro MicroSystems
955 Perimeter Road Manchester, NH 03103-3353 U.S.A.
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References
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