Hi everybody,
I have a problem with the charge pump of this IC. Its voltage doesn't reach -VDD to full extent.
The circuit is supplied by +5V. The pump's voltage doesn't exceed the voltage of -2.8V, even if there's no signal applied to the IC's inputs.
Please find schematic and oscillograms below!
I already tried the following to fix the issue:
1. replaced bypass caps on pin 20/12 by 10uF/16V/20% X5R MLCC, CPVSS remains on -2.8V
2. paralleled caps (1uF/16V/20% X5R MLCC) between pins 17 and 18 and 15/16 to GND with 100nF/50V/20% X7R MLCC in order to lower ESR, CPVSS remains on -2.8V
3. measured all GND-pin's resistance to the GND plane - they are all fine
4. measured all VDD-pin's resistance to +5V supply layer - they are all fine
Is there anybody out there who experienced the same issue or has some advice?
Thank You!
Schematic:
yellow: CPP, green: CPN, blue: difference between CPP/CPN
VDD:
CPVSS:
