To Verify the driving capacity of TPS61199 on Multiple LED bars, the configuration of LED bars for each channel include 2 strings of LED's in parallel, each with 16 LED's (8 in the light bar and 8 in the LED LOAD board), shown as below, the forward voltage of each LED is around 2.8V:
TPS61199EVM-598 is been used, which the VIN = 12V from external power supply, and a square waveform (Low = 0V, High=3.3V), is been provided by a Waveform Generator:
Single Channel is been verified, and the LED driver is able to provided a current up to 48mA (Measured from the sink).
However, when the same configuration is been tested on 8 channels together, only some of the LED strings are been lit. (The other strings lit up and turned off after enabling the PWM signal).
We have tried to switch the PWM frequency from 1KHz to 20 KHz, and was able to lit up all LED strings at first try, but was unable to replicate afterwards. (The issue as before switching the PWM)
We have reduced the number of LED's to 12 in each string, and never encounter the issue. (at PWM frequency of 1 kHZ and 20 kHz)
Please advice the potential cause and solution of the issue, so we can evaluate the maximum number of LED's driving by TPS61199, Thank You!
