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TLC69628-Q1: AHVC Feedback Not Updating

amazigh moulla
Prodigy 10 points
Part Number: TLC69628-Q1

Tool/software:

Hello,

I'm currently testing the TLC69628-Q1 evaluation board, and I'm having trouble getting the automatic feedback (AHVC) mode to work properly.

We ran tests using both settings for the MUL_MODE register (manual mode and AHVC mode):

  • In manual mode, setting FB_CUR gives the expected current on the FB pin — this works fine.

  • In AHVC mode, we can still measure the current defined in FB_CUR, but it never updates, even after multiple VSYNC commands are sent.

So far, AHVC_RES does not seem to change, and the feedback current remains fixed.

We would like to understand what is needed to get automatic headroom voltage control working correctly.
Below is an example SPI script we are using to configure the drivers:

Fullscreen Script_TLC69628_SPI_96LEDs_5mA_NoCRC.xml Download 
<aardvark>
    <configure i2c="0" spi="1" gpio="1" tpower="0" pullups="0"/>
    <spi_bitrate khz="1000"/>
	
    <spi_config polarity="rising/falling" phase="sample/setup" bitorder="msb" ss="active_low"/>

        <spi_write count="14"  radix="16" >55 00 00 01 00 01 1A 94 FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>

        <spi_write count="18"  radix="16" >55 20 00 03 02 00 02 00 02 70 C4 66 FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>
	
	    <spi_write count="88"  radix="16" >55 20 00 26 02 00 48 00 02 70 03 20 14 E0 00 00 F9 80 00 00 07 E0 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 00 00 00 00 00 00 00 00 00 01 CB 77 FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>

	    <spi_write count="18"  radix="16" >55 40 00 03 04 02 04 02 03 30 FF FF FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>
             
            <spi_write count="18"  radix="16" >55 20 00 03 02 00 02 00 02 71 FF FF FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/> 
	
	    <spi_write count="112" radix="16" >55 60 00 62 00 01 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF FF FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>

	    <spi_write count="16"  radix="16" >55 B0 00 02 00 00 00 00 FF FF FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>
	
	    <spi_write count="112" radix="16" >55 60 00 62 00 01 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF FF FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>

	    <spi_write count="16"  radix="16" >55 B0 00 02 00 00 00 00 FF FF FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>
	    
		<spi_write count="112" radix="16" >55 60 00 62 00 01 00 02 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 15 55 FF FF FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>

	    <spi_write count="16"  radix="16" >55 B0 00 02 00 00 00 00 FF FF FF FF FF FF FF FF</spi_write>
    <sleep ms="100"/>

</aardvark>