Allegro A80803 Manuel utilisateur

User Manual

A80803 Evaluation Board and Programming GUI

UM-A80803, Rev. 1

MCO-0001115

February 4, 2022

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 Part Number Low/High-Beam

Support

Low-Beam

Topology

High-Beam

Topology

Low/High Beam Topology Switch APEK80803KET-TS Yes Buck-Boost Boost

Low/High Beam Single FET APEK80803KET-SF Yes Boost Boost

Boost Only APEK80803KET-BO No Boost –

Buck-Boost Only APEK80803KET-BB No Buck-Boost –

Figure 1: A80803 EVB

Table of Contents

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

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

Allegro MicroSystems

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

GENERAL SETUP

This section provides an overview of the connections that are generally applicable to all EVB configurations. Each group of connec-

tions is highlighted in Figure 2.

Figure 2: A80803 EVB I/O Connections

Power Input

Connect a power supply using the either X1 terminal block or the VBAT and GND test points.

LED Connection

Connect the anode of the LED string to the X2 connector terminal A (anode) and the cathode of the LED string to the X2 connec-

tor terminal K (cathode). For low/high-beam applications, tie the CT terminal to the LED string to mark the bottom of the low-beam

string. The APEK80803KET-BB and APEK80803KET-BO options have R18 and R23 installed to tie CT to the K terminal.

Control Pins

The LBEAMn, EN/PWM, and DIMn pins of the A80803 can be tied to VIN with jumpers or left open and controlled with external

signals. These test points could be tied to VIN externally or driven from a logic level source such as a microcontroller.

The jumpers J1, J2, and J3 can be installed or opened to set the operating state as shown in Table 2 and Table 3. To operate in external

dimming mode, install 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.

Table 2: Low/High-Beam Jumper

J1 (LBEAMn) State

Open Low-Beam

Installed High-Beam

Allegro MicroSystems

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Table 3: Internal/External Dimming Jumpers

J2 (DIMn) J3 (EN/PWM) Dimming Mode

Installed Installed External - 100%

Installed Open External - PWM

Open Installed Internal

Bin Select

Jumpers J4 to J7 select the bin for analog dimming.

Note: Only one bin select jumper should be installed at a time. See Table 4 for bin selection.

Table 4: BIN Selection Jumpers

Jumper Installed BIN

J4 BIN1 selected

J5 BIN2 selected

J6 BIN3 selected

J7 BIN4 selected

Gain can be modified for each bin using the A80803 GUI tool; see the Binning Tab section of this document. The jumpers J4 to J7

select a resistor for the bottom of a voltage divider. If all four jumpers are open, the BINSEL pin will be pulled up to VCC and BIN1

will be selected.

SPI Communication

The A80803 supports SPI for serial communication to control the configuration registers. The silkscreen labels are intended for use

with the FTDI USB to Serial adapter cable, part number C232HM-EDHSL-0, to be used with the A80803 GUI tool. See Table 5 to

compare the silkscreen labels to the SPI pin names. The jumpers J1, J2, and J3 can be installed or opened to set the operating state as

shown in Table 2 and Table 3. To operate in external dimming mode, install 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.

Table 5: J8 Header SPI Labels

Silkscreen Label USB-Serial Breakout Wire SPI Pin

ORN Orange SCK

YEL Yellow MOSI

GRN Green MISO

BRN Brown CSn

BLK Black GND

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 VCC with a 10 kΩ resistor on the EVB.

Allegro MicroSystems

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

Sense Resistor

The LED current is set by the sense resistor R2 and the equation:

ILED = VIDL / R2

Each EVB configuration is designed for a 1 A LED current; with VIDL = 200 mV then R2 = 0.2 Ω.

Switching Frequency

The switching frequency for the power converter stage is set by R16 and the equation:

fSW = 35000 / R16

where fSW is in kHz and R16 is in kΩ. Each EVB configuration is designed for a switching frequency of 400 kHz with R16 = 86.6 kΩ.

NTC LED Current Derating

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.

Allegro MicroSystems

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

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.

Note: Text highlighted in blue monospaced font refers to a button in the GUI.

The tool opens to the Diagnostic tab but does not attempt to communicate with the part until the user requests a read or write opera-

tion. The initial state of the GUI is shown below in Figure 3.

Figure 3: First screen after starting the GUI

Figure 4: USB Serial Connection Established

Press the Read Faults button to start a read and initialize the USB connection. Upon successful connection, the USB status will

change to USB Connected in green text in the bottom left corner of the window.

Allegro MicroSystems

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

At the top of the diagnostics tab there are buttons to read all configuration data from shadow or EEPROM into the state of GUI

controls, and to write the full state of the GUI controls to the configuration registers or EEPROM. A good practice is read the shadow

registers, once the connection to the A80803 has been established, by clicking the Read Shadow button shown in Figure 5, to align the

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.

Figure 5: Read All of Shadow to Align GUI Controls with the Device

Allegro MicroSystems

955 Perimeter Road

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If this error appears and the D2xx drivers are believed to be installed, then ensure the USB cable is fully connected to the PC. If the

USB cable was recently plugged-in, then ensure the PC has had enough time to recognize the USB device.

If the GUI shows USB Connected and Parity check failed as shown in Figure 7, this means the USB-to-serial converter is con-

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.

Figure 7: GUI is connected to USB-Serial but cannot nd A80803

The window on the right side of the GUI window shows the details of each SPI transaction as they are processed. The bottom of the

window shows the diagnostic information from on the MISO pin after each SPI read or write. See the Serial Communication section in

the datasheet for more details about the SPI interface.

GUI Troubleshooting

After the first read or write request, the tool will attempt to communicate using the FTDI D2xx driver. If the driver is not installed, or

the FTDI USB-Serial device cannot be found, an error message will be displayed as shown in Figure 6.

Figure 6: Error when FTDI device cannot be found

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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. The numbers in

the button label indicate the Config registers affected. There is also a checkbox near the top of the window for Write to register

every change which will update configuration registers every time a change is made without having to make the change and click

the Write button.

Figure 8: Read, Write, and Write Every Change

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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 afile..., and select a location and name the file, shown in Figure 9. Recall this configura-

tion by clicking the Save/Open Configuration button, select Open device configuration file..., and select the file to

load. After loading a configuration file, the GUI will update to match the state when it was saved.

At any time, the factory default EEPROM state can be loaded into the GUI controls by selecting Load default configuration to

application option from the Save/Open menu.

Note: Loading a configuration (including the default) does not automatically send the configuration to the device, giving an oppor-

tunity to modify a loaded configuration before writing to the device.

Figure 9: Save and Load Conguration Files

Allegro MicroSystems

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

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 button is pressed. The fault status indicators will be green and show a value of 0 when no fault is present

and red with a value of 1 when a fault is present. Some faults are latched and must be cleared with the Clear Faults button. See

DIAG0 and DIAG1 register descriptions in the datasheet for more information.

Figure 10: Fault Indicators

The bottom of the GUI window shows the faults that are on the MISO line during every SPI transaction. The faults in gray in Fig-

ure 10 are only available on the MISO line during a write. See the SPI Data Frames section of the datasheet for more information.

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