Other Parts Discussed in Thread: TPS61199EVM-598, TPS61169
Tool/software:
Hi Sir,
My customer verified the driving capacity to connect 2 of TPS61169EVM on display back-light LEDs and found the below issues.
Could you please advise some comments and suggest the correct device of LED driver for their request? Thanks!
The system configuration: (same as design conditions)
The back-light LED bars configured for 4 channel a set(IFB1~IFB4=100mA) include 3 strings of LED's in parallel, each with 6 LED's(total 72 LEDs), the forward voltage of each LED is around 2.8V. So, the total V-out=18V, I-out=400mA.
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, PWM frequency at 100Hz to 2KHz with duty cycle 1%~100%
Issues list:
1. Please refer to the attachments, the input voltage has unstable or got drop, when the PWM frequency at 2KHz with duty cycle from 50% to 99%.
2. In the low PWM frequency 100Hz and 500Hz, they could seen the back-light LEDs have the blinking issue. Even the PWM frequency at 2KHz, the back-light LEDs has flickering slightly.
3. When TPS61169EVM with display back-light to do the system boot-up, they could heard the EVM has the buzzing noise slightly.
