This circuit is used to drive a 4-LED Series LCD backlight, but there will be a burst of flicker and a burst of normal. Measure the PWM waveform, and it is found that the duty cycle will change when flashing. The welding problem has been eliminated. Please help to analyze the cause?Here's the waveform and blinking video
C117 = 220nF has been tried without improvement. The waveforms when flashing and normal are tested as follows. Figure 1 is the VIN waveform, figure 2 is the Vout waveform when flashing, figure 3 is the normal Vout waveform, figure 4 is the SW waveform when flashing, figure 5 is the SW waveform when normal, Figure 6 is the PCB U19 is TPS 61160, l = 22uh, and D21 is the MBR0520, How to light the backlight normally and no longer blink?
