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INTRODUCTION
The A80803 Evaluation Board (EVB) is designed to aid sys-
tem designers with the evaluation of the operation and per-
formance of the A80803, a multi-topology, fixed frequency,
switch-mode DC/DC controller for LED lighting applica-
tions with built-in support for low/high-beam operation and
remote configuration via SPI.
The A80803 EVB is available in four configurations to sup-
port low/high-beam and fixed LED string applications. The
EVB arrives configured to operate in one of four modes and
has a mark on one of the silkscreen boxes in the top right of
the EVB to identify in which mode the EVB is configured.
The Allegro A80803 configuration GUI is a tool provided to
simplify interaction with the device using the SPI interface.
The tool can read and write all configuration registers as
well as report and clear the fault status and diagnostic bits.
The tool provides a tabbed interface to group similar options
together to help the user quickly find configuration options.
The GUI is not required for operation but simplifies con-
figuration register modifications.
Table 1: A80803 EVB Available Configurations
Configuration Name
Low/High Beam Topology Switch
Low/High Beam Single FET
Boost Only
Buck-Boost Only
Introduction ...................................................................................1
General Setup ...............................................................................2
Power Input ...............................................................................2
LED Connection ........................................................................2
Control Pins ...............................................................................2
Bin Select ..................................................................................3
SPI Communication ...................................................................3
Fault Flags .................................................................................3
Sense Resistor ..........................................................................4
Switching Frequency .................................................................4
NTC LED Current Derating .......................................................4
Getting Started with the GUI .........................................................5
GUI Troubleshooting .................................................................7
Device Configuration .................................................................8
Configuration Files and Default EEPROM ............................ 9
Diagnostics Tab ...................................................................10
Configuration Tab ................................................................ 11
Binning Tab .......................................................................... 11
Thermal Foldback Tab .........................................................12
VIN Foldback Tab ................................................................12
UM-A80803, Rev. 1
MCO-0001115
A80803 Evaluation Board and Programming GUI
Low/High-Beam
Part Number
APEK80803KET-TS
APEK80803KET-SF
APEK80803KET-BO
APEK80803KET-BB
Table of Contents
Figure 1: A80803 EVB
Low-Beam
Support
Topology
Yes
Buck-Boost
Yes
Boost
No
Boost
No
Buck-Boost
PWM Dimming Tab ..............................................................13
High/Low-Beam Tab ............................................................14
Faults Flags Tab ..................................................................15
Writing to EEPROM .................................................................16
Low/High-Beam Topology Switch EVB .......................................17
APEK80803KET-TS Schematic ..............................................18
APEK80803KET-TS Bill of Materials .......................................19
Low/High-Beam Single FET EVB ...............................................20
Confirm HBGCTRL Bit.............................................................21
APEK80803KET-SF Schematic ..............................................22
APEK80803KET-SF Bill of Materials .......................................23
Boost Only EVB ..........................................................................24
APEK80803KET-BO Schematic ..............................................25
APEK80803KET-BO Bill of Materials ......................................26
Buck-Boost Only EVB .................................................................27
APEK80803KET-BB Schematic ..............................................28
APEK80803KET-BB Bill of Materials .......................................29
Board Layout ...............................................................................30
Revision History ..........................................................................32
User Manual
High-Beam
Topology
Boost
Boost
-
-
February 4, 2022
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Summary of Contents for Allegro A80803
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Page 1: Table Of Contents
User Manual A80803 Evaluation Board and Programming GUI INTRODUCTION The A80803 Evaluation Board (EVB) is designed to aid sys- tem designers with the evaluation of the operation and per- formance of the A80803, a multi-topology, fixed frequency, switch-mode DC/DC controller for LED lighting applica- tions with built-in support for low/high-beam operation and remote configuration via SPI. -
Page 2: General Setup
J2 or tie DIMn to a logic high signal and EN/PWM to an external PWM source for controlled dimming or logic high for 100% dimming. To use internal dimming, open J2 and connect EN/PWM to logic high or install J3 and use the A80803 GUI tool to set the LED brightness. -
Page 3: Bin Select
Black Fault Flags There are two active low fault flag pins on the A80803, FFn1 and FFn2. Both are available as test points on the EVB. The fault flags are pulled up to V with a 10 kΩ resistor on the EVB. -
Page 4: Sense Resistor
There is a NTC thermistor on the EVB, RT1, in a voltage divider leading to the NTC pin. The thermistor, part number NTCS0603E- 3103FHT, has a base resistance of 10 kΩ. See the Thermal Derating section in the A80803 datasheet for more information about programming the derating values. -
Page 5: Getting Started With The Gui
GETTING STARTED WITH THE GUI Download the A80803 GUI tool from https://registration.allegromicro.com. The GUI tool is an executable that can be run directly without any additional installation steps once downloaded and extracted. The tool depends on the FTDI D2xx driver for USB to Serial communication. - Page 6 GUI controls with the state of the device. Reading the full contents of the EEPROM can be used to understand what is programmed into EEPROM and is loaded into shadow at each power-on, but the shadow registers are what the A80803 uses during operation.
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Page 7: Gui Troubleshooting
Parity check failed nected but cannot communicate to the A80803. Ensure the A80803 SPI pins are properly connected in the correct order (refer to the SPI Communication section of this document), and the device is powered. A parity error while reading the fault registers will reset the fault indicators to black text to indicate the state is unknown. -
Page 8: Device Configuration
Device Configuration Each of the other tabs after the Diagnostics tab has two buttons in the top right corner, one to read just the registers represented on that tab, Read config, and one to write the state of the GUI controls in that tab to those registers, Write config. -
Page 9: Configuration Files And Default Eeprom
Configuration Files and Default EEPROM The GUI tool has an option to save its state to a file to be recalled later. Click on the Save/Open Configuration menu item, then click Save this configuration to a file..., and select a location and name the file, shown in Figure 9. Recall this configura- tion by clicking the Save/Open Configuration button, select... -
Page 10: Diagnostics Tab
Diagnostic Tab In addition to the buttons to read or write the full register set, the Diagnostic tab also shows the status of the faults captured in the DIAG0 and DIAG1 registers. The fault status indicators will update with each click of the Read Faults button or continuously if the Continuous Fault Read... -
Page 11: Configuration Tab
Configuration Tab The Configuration tab provides several general purpose options to configure the A80803, as shown in Figure 11. Figure 11: General Configuration Binning Tab The Binning tab has four sliders to control the bin gain for each of the four bins. The binning level acts as a derating for the maximum LED current. -
Page 12: Thermal Foldback Tab
Thermal Foldback Tab The Thermal Foldback tab has sliders for the NTC analog dimming options. See the Thermal Derating section and the Thermal Derat- ing Example in the datasheet for more information about calculating these values. Figure 13: Thermal Foldback Configuration VIN Foldback Tab The VIN Foldback tab has sliders for the VIN derating analog dimming options. -
Page 13: Pwm Dimming Tab
PWMOUT gate driver for both inter- nal and external PWM dimming. See the LED PWM Dimming section of the datasheet for more information about PWM dimming with the A80803. Note: If the DIMn pin is low, the... -
Page 14: High/Low-Beam Tab
High/Low-Beam Tab The High/Low-Beam tab has options to set the overvoltage and undervoltage thresholds for both low-beam and high-beam, the overvoltage behavior, the additional dead time setting, and high-beam gate controls. The high-beam gate can be forced on with the High-beam Gate On/Off option, and the HBG Control... -
Page 15: Faults Flags Tab
Fault Flags Tab The Fault Flags tab has options to set which faults are reported on FFn2, the FFn2 delay, the overcurrent detection filter, and the one- out-all-out behavior. Figure 17: Fault Flag Configuration Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com... -
Page 16: Writing To Eeprom
To unlock and write EEPROM with the GUI, follow this procedure: 1. Power on the device and read the faults to verify communication. 2. Power cycle the A80803 while keeping the GUI open. 3. Click the button (this must be first button after A80803 is powered). -
Page 17: Low/High-Beam Topology Switch Evb
LOW/HIGH-BEAM TOPOLOGY SWITCH EVB The low/high-beam topology switch configuration operates in buck-boost mode while in low-beam and in boost mode while in high- beam. This allows for shorter low-beam strings that may have an output voltage less than the input voltage. Connect the LED string to terminal block X2 as shown in Figure 19, where terminal A to CT is the low-beam string, and terminal A to K is the high-beam string. -
Page 18: Apek80803Ket-Ts Schematic
APEK80803KET-TS SCHEMATIC Figure 20: APEK80803KET-TS Schematic Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com... -
Page 19: Apek80803Ket-Ts Bill Of Materials
APEK80803KET-TS Bill of Materials Designator Description Quantity Manufacturer Manufacturer P/N A80803 in the QFN-32 Allegro MicroSystems Capacitor, Ceramic, 0.1 µF, 50 V, X7R, 0603 C2, C3, C4 Capacitor, Ceramic, 4.7 µF, 50 V, X7R, 1210 Murata GCM32ER71H475KA55K C5, C9 Capacitor, Ceramic, 0.1 µF, 50 V, X7R, 0805 C6, C7, C8 Capacitor, Ceramic, 4.7 µF, 100 V, X7R, 1210... -
Page 20: Low/High-Beam Single Fet Evb
LOW/HIGH-BEAM SINGLE FET EVB The low/high-beam single FET configuration operates in boost mode for both low-beam and high-beam and shorts out the high-beam part of the LED string while in low-beam. The LED string must have enough LEDs for the boost output voltage to be higher than the input voltage for both low-beam and high-beam. -
Page 21: Confirm Hbgctrl Bit
(J3 installed, J2 open), then read back EEPROM and check the HBGCTRL bit. If HBGCTRL = 0, the EEPROM must be updated before the device can be used for driving LEDs. This process is illustrated in the figures below using the A80803 GUI tool. -
Page 22: Apek80803Ket-Sf Schematic
If HBG Control is set for Mode, then refer to the Writing to EEPROM section and follow the steps below to con- Topology Change figure the device properly for this application. 1. Power-cycle the device. 2. Unlock the EEPROM for writes. 3. -
Page 23: Apek80803Ket-Sf Bill Of Materials
APEK80803KET-SF Bill of Materials Designator Description Quantity Manufacturer Manufacturer P/N A80803 in the QFN-32 Allegro MicroSystems A80803KETASR Capacitor, Ceramic, 0.1 µF, 50 V, X7R, 0603 C2, C3, C4 Capacitor, Ceramic, 4.7 µF, 50 V, X7R, 1210 Murata GCM32ER71H475KA55K C5, C9 Capacitor, Ceramic, 0.1 µF, 50 V, X7R, 0805... -
Page 24: Boost Only Evb
BOOST ONLY EVB The boost only configuration operates in boost mode without an option for low-beam or high-beam. The EVB should only oper- ate low-beam mode in this configuration for the fault detection to work properly. Connect the LED string to terminal block X2 as shown in Figure 24, where the LEDs connect between the anode terminal A and the cathode terminal K. -
Page 25: Apek80803Ket-Bo Schematic
APEK80803KET-BO SCHEMATIC Figure 25: APEK80803KET-BO Schematic Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com... -
Page 26: Apek80803Ket-Bo Bill Of Materials
APEK80803KET-BO Bill of Materials Designator Description Quantity Manufacturer Manufacturer P/N A80803 in the QFN-32 Allegro MicroSystems A80803KETASR Capacitor, Ceramic, 0.1 µF, 50 V, X7R, 0603 C2, C3, C4 Capacitor, Ceramic, 4.7 µF, 50 V, X7R, 1210 Murata GCM32ER71H475KA55K C5, C9 Capacitor, Ceramic, 0.1 µF, 50 V, X7R, 0805... -
Page 27: Buck-Boost Only Evb
BUCK-BOOST ONLY EVB The buck-boost only configuration operates in buck-boost mode without an option for low-beam or high-beam. The EVB should only operate in low-beam mode in this configuration for the fault detection to work properly. Connect the LED string to terminal block X2 as shown in Figure 26, where the LEDs connect between the anode terminal A and the cathode terminal K. -
Page 28: Apek80803Ket-Bb Schematic
APEK80803KET-BB SCHEMATIC Figure 27: APEK80803KET-BB Schematic R29 was added post-fabrication to connect the LED cathode to VIN through diode D4. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com... -
Page 29: Apek80803Ket-Bb Bill Of Materials
APEK80803KET-BB Bill of Materials Designator Description Quantity Manufacturer Manufacturer P/N A80803 in the QFN-32 Allegro MicroSystems A80803KETASR Capacitor, Ceramic, 0.1 µF, 50 V, X7R, 0603 C2, C3, C4 Capacitor, Ceramic, 4.7 µF, 50 V, X7R, 1210 Murata GCM32ER71H475KA55K C5, C9 Capacitor, Ceramic, 0.1 µF, 50 V, X7R, 0805... -
Page 30: Board Layout
BOARD LAYOUT Figure 28: Top Layer Figure 29: Inner Layer 1 (GND Plane) Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com... - Page 31 Figure 30: Inner Layer 2 Figure 31: Bottom Layer Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com...
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Page 32: Revision History
Revision History Number Date Description – June 25, 2021 Initial Release February 4, 2022 Corrected table 5 (page 3) Copyright 2022, 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.
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