TPS25751: TPS25751D Source Configuration - PP5V Issue

Part Number: TPS25751

Hi,

I have a custom board design that uses the TPS25751D for a source port configuration. The PD controller is configured via EEPROM to support 5V,9V, and 12V PDOs.

I'm unable to get a 5V output through the PD controller when a 5V PDO is negotiated with an attached sink device. The output of the PD controller oscillates between 4.4V and 5.1V continuously despite a successful PDO contract negotiation. The PP5V input remains stable at 5.1V even though the output of the PD controller is oscillating.

Here is a log of register values collected while monitoring the PP5V and output.

# i2ctransfer -y 7 w1@0x23 0x03 r5                                                                                               

0x04 0x41 0x50 0x50 0x20                                                                                                         

# i2ctransfer -y 7 w1@0x23 0x26 r6                                                                                               

0x05 0x82 0x00 0x00 0x00 0x40                                                                                                    

# i2ctransfer -y 7 w1@0x23 0x34 r5                                                                                               

0x06 0x2c 0x91 0x01 0x23 

I tried bypassing the 5V input to the PD controller and instead provided the power input using an external bench supply. In this configuration, the PD controller worked as expected for all PDOs.

I noticed after reviewing the design checklist for this part that I may have insufficient capacitance on the PP5V pins.  The PPHV power path works fine even though it also seems to have insufficient capactiance. 

Any thoughts on what could possibly be causing this issue? Please see a screenshot of the schematic below for reference.