• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 125 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LP5811: Current consumption is ~70mA on average during animation with Red LED

Prodromos Kampas
Prodigy 10 points
Part Number: LP5811

Tool/software:

Hello,

  • We are using a LP5811BYBHR 4-channel LED driver controlled via I²C.

  • Power for the LEDs is supplied via VOUTs

  • We are running an animation where:

    • Red LED ON for 180ms

    • OFF for 360ms

The total measured current remains ~70mA, even during "off" time. I am attaching the schematic as well as the current consumption measured at 3.8V VBAT.

The LEDs brightness is set to 100% at value 255. Is the current consumption normal or do we have a software / hardware issue?

  • 0
    TI__Expert 5600 points

    Hi Prodromos,

    There are three questions,

    1. What's the boost_vout and max_current setting for the red LED?
    2. Are there other LEDs kept ON while red LED is turned on/off?
    3. Why is there current ripple measured on the VBAT as marked below? Any other operations are taken at the moment?

    Best regards,

    Felix

  • 0 in reply to Felix Wang
    Prodigy 10 points

    Hi Felix,

    1. The boost Vout is 3.0V. The  max current setting is 25.5mA.

    2. Only the red LED is blinking. 

    3. The ripple current is coming from an audio signal. Sorry about that. I am attaching the current consumption by the LED here.

    Because we are using the software for the LED driver that was provided by a third party we want to ensure that there is no hardware misconfiguration. We use the animation unit for blinking the red LED, 180ms ON and 360ms OFF.

  • 0 in reply to Prodromos Kampas
    TI__Expert 5600 points

    Hi Prodromos,

    Does the VBAT provide the power for other components on the board? Not sure why there is still about 60mA current when red LED is off. however the delta current is about 25.5mA that seems to be correct.

    Is it possible measure the current here as marked below?

    Best regards,

    Felix

  • 0 in reply to Felix Wang
    Prodigy 10 points

    Hi Felix,

    It turned out to be a register misconfiguration. We were setting the VSYNC bit of the DEV_CONFIG_11 register to output instead of input which caused this unexpectedly high current consumption.

    It would be super helpful if you could answer why this lead to the high current consumption. Is this the expected behavior?

  • +1 in reply to Prodromos Kampas
    TI__Expert 5600 points

    Hi Prodromos,

    Yes, when the VSYNC output is enabled a 6MHz clock signal will be output through the VSYNC terminal, which high level voltage is VCC and low level voltage is GND. As on the board the VSYNC is constantly pulled down to GND, so there will be high current when the output is high.

    Best regards,

    Felix