LP5569: I can do I2C transactions but cannot get any LEDs to turn on

David Burton

Part Number: LP5569

I have this controller designed into my board and am attempting to verify functionality with an Aardvark I2C/SPI - USB device. The transactions and responses look correct. I can write the enable register and see the output power turns on at 1x. After that I can get no further response. Setting 1.5x or auto dosen't seem to do anything. Attempting to turn on any output results in no current being sunk.

I've tried with auto reg incrementing and without.

Here is a sample instruction sequence:

<i2c_bitrate khz="10"/> bitrate 10kHz

    <i2c_write addr="0x32" count="2" radix="16">00 40</i2c_write> enable the part
    <i2c_write addr="0x32" count="2" radix="16">2f 08</i2c_write> set up the MISC reg

    <i2c_write addr="0x32" count="2" radix="16">22 40</i2c_write> writing LED current controls
    <sleep ms="500"/> pause 500 msec
    <i2c_write addr="0x32" count="2" radix="16">23 40</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">24 40</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">25 40</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">26 40</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">27 40</i2c_write>
    <sleep ms="500"/>

    <i2c_write addr="0x32" count="2" radix="16">22 00</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">23 00</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">24 00</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">25 00</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">26 00</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">27 00</i2c_write>
    <sleep ms="500"/>

    <i2c_write addr="0x32" count="2" radix="16">22 8f</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">23 8f</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">24 8f</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">25 8f</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">26 8f</i2c_write>
    <sleep ms="500"/>
    <i2c_write addr="0x32" count="2" radix="16">27 8f</i2c_write>
    <sleep ms="500"/>

Any ideas what I am missing here?

Thanks,

David B

over 6 years ago

0 David Burton over 6 years ago

Expert 1330 points

Added internal clk selection but still doesn't work. All controls and registers seem to R/W and function correctly, except I can't get any LED current to sink. Tested GPIO output and controls as expected. It's like I'm missing some output enable bit, but I have the part enabled and the internal clock set and I'm not sure what else needs to be done to this to get some LED action. I also confirmed the internal clock is running by setting it to the output pin.

0 David Burton over 6 years ago in reply to David Burton

Expert 1330 points

My circuit:

0 Kenneth Du over 6 years ago in reply to David Burton

TI__Genius 14295 points

Hi, David,

Let me check this and reply you before the weekend.

Thanks.
Kenneth

0 David Burton over 6 years ago in reply to David Burton

Expert 1330 points

OK. I figured this out. I didn't see it explicitly explained anywhere but the PWM and current registers must be used together. 0 PWM or 0 current keeps all LEDS off. I had assumed the default PWM registers would mean "No" PWM function active, but it is actually 0 duty cycle.

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LP5569: I can do I2C transactions but cannot get any LEDs to turn on