Hi ,
we have some problems in using tps92641 led driver:
1、 Operating Conditions：
1) We use 10 TPS92641 driver channels to drive 10 LED channels，each channel can be individually control;
2) The color of each drive channel is different, and the forward voltage of the corresponding LED is different. Therefore, the maximum voltage of each driver channel will be different;
3) VCC Input 48V ；
4) Each channel has 12 strings of 6 leds, and the maximum forward current of each LED is 350mA, and the total maximum current is about 2.1A;The maximum voltage range of single-channel drive voltage is 27~40V;
5) The dimming method is analog signal dimming;
2、 Problem Description:
After each power on, some channels may have no voltage output at low dimming levels. The dimming level needs to be set high to have voltage output. Once there is a voltage output, the control signal is lower to have a voltage output. The problem seems to require a power-on activation threshold.
For example, after power on, there is no voltage output for the dimming level between 1% and 9%, and it needs to be adjusted the dimming level to 10% to make the voltage output.As soon as there is an output, the dimming level is lower than 10% brightness, and there is a voltage output.
The distribution of the channel with this problem is random in each PCB board. After some channel of a board appears, it usually appears continuously. But sometimes the activation threshold changes.
We found that we set the dimming level of the problem channel to 0% before power on, and then power on, the SW/HG/LG pin has no signal output; there is no output until the dimming level exceeds the power-on activation threshold.
Any suggestions to solve this problem?
Best regards,
shaoqin.zheng
