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LP8556: One string operation with PWM Only EPROM config

Dimitri Georgaras
Prodigy 50 points
Part Number: LP8556

Hello,

I have an LCD with an LED backlight which only has 2 strings of LEDs with the following specifications:

1. I am using the E06 in another section of the board for PWM control of 5 LED strings. I was wondering if there is a configuration where I can use the E06 for this LCD backlight without having to configure the device with I2C to disable the channels not being used?

2. I have read in other forum posts that if I leave a channel open/not connected, the adaptive boost will drive to it's maximum boost voltage. Is my understanding of this operation correct? What would the boost voltage be with a 5V input?

3. How would this configuration effect efficiency of the device?

4. With the pre-configured EPROM set to CURRENT_MAX at 25mA, will I be able to set the max current to 40mA using the ISET resistor? 

Thank you,

Dimitri

  • 0
    TI__Genius 13001 points

    Hi Dimitri,

    1. The channels can be configured only by I2C.

    2. Yes, the max. voltage can be set through I2C.

    3. Sorry, we don't have this typical value. It needs bench test.

    4. Please refer to section 8.6.2.6 of the datasheet. You can configure the resistor by setting ISET_EN=1.

    BR,

    Robin