VGL issue
IC Name: TPS651851
Application: 13.3" e-paper
Question: I'm designing a power supply board for e-paper. The voltage input/output is as follows:
VIN: 5V
LDO1 (VPOS): +15V
LDO2 (VNEG): -15V
CP1 (VDDH): +25V
CP2 (VGL): -20V
Vcom set (I2c): -5V~0V
The reference circuit is as follows:
After exposure to 60°C, the VGL voltage changes from -18V to 17V. Could an experienced engineer tell me where the problem lies? Thank you.
I tried a few things (experiments):
1. Replaced the VGL C66 CAP (4.7uF) from 35V to 50V.
2. Increased VGH from 25V to 27V.
3. If there's a problem with VGL, the voltage is reduced to -18V and cannot be restored unless the TPS651851 is replaced. Finally, the output returned to normal.
