LP8866-Q1: LP8866-Q1: PWM of LP8866 is adjusted to the maximum, the backlight will flash

Hi, Bruce, 

What is read back register data. especially for 0Eh, 10h and 12h. During flash, if INT been pulled low? 

Regards, 

Xiaoguang 

Hi,We found that it was this start overcurrent that caused the interrupt INT kept low level. May I ask what caused this, thank you!

It runs into over current protection. Please try reducing R200 value - like 25-30mohm to see if it works. 

Regards, 

XG 

Hi, xiaoguang

We have tried that, but still the same problem, any other advices?

Thanks,

Bruce Yang

Bruce, 

You may try advanced sloper to smooth brightness transitions, increasing output capacitance as well. 

With INT pin trigger, to see below waveform with oscilloscope; showing each item in a plot.
(1). Vin, Vsen_N, SD
(2). Switching node, GD, ISNS, Vout
(3). Vout, LEDx, FB

(4). LED current 

Hi XG,

LP8866 output waveform I have captured, the PWM input pin has been set high, VBOOST and VLED voltage output abnormal, INT also output low level.

Increasing the output capacitance is also useless;

Do you have LP8866 DEMO debug board? Will it flash when PWM pin is set high and load is added?

Regards,

Bruce Yang

Hi, Bruce, 

No, it will not flash on EVM board. Could you help share the tested waveform as attached? If possible, pls also test L4 current with INT low triggers. 

Hi Xiaoguang,

I have sent the testing waveform to you via email.

Thanks!

Dylan