Hello,
We are currently developing a device in which we want to use the TPS65988DH in the configuration given below:
Power is only provided via two USB-C Connectors, the device has no onboard batteries.
In Use Case 1 our device is connected to a laptop or pc via an USB C plug to Port 1 of the TPS65988, the Laptop/PC Sources power to the device and is the DFP for the data connection.
in Use Case 2 a Power Brick with USB-PD is connected to Port 2 of the TPS65988 and upto 20V is nogotiated, the device is now powered by the Power Brick, we also want to power the laptop/PC using the Power Brick, as such, the Laptop/PC has to switch power mode to Sink.
I've been experimenting with the TPS65988EVM, with limited succes, on port 2 i'm able to negiotiate a power contract with the power brick so i don't expect any problems there.
For port 1 i'm unable to switch from sink to source. i'm using the port settings below:
On the TPS65988EVM i've removed the jumpers on the PP_HV1/2, A/B-VAR SYSPWR and PPEXT1/2 pins with the intention to place a jumper on the PP_HV1 and PP_H2 pins to emulate the intended behaviour.
I perform the following steps (which will be automated in the application):
Note: the Jumper between PP_HV1 and PP_HV2 is not placed during these tests
#1: EVM Port 1 is connected to a Laptop, a 5V/3A Contract is negotiated.
#2: Laptop Sink Capabilties are requested via single GSkC Command
#3: EVM Port 2 is connected to a Power Brick, a 9V/3A Contract is negotiated.
#4: Single SRDY command is issued on Port 2, 9V is now available on PP_HV2 pin
#5: Single SWSr command is issued on Port 1 to switch from Sink to Source, an ABORT or REJECT reply issued.
In the status register (0x1A) the Port Role is now (sometimes) Source, when placing the jumper on P_HV1 and PP_HV2 to provide power to Port 1 the port status starts continuously alternate between Source and Sink without providing power to the Laptop.
Is there something wrong in my settings, in the order of steps listed above or is the behaviour envisioned by us not possible with the TPS65988?
Note: no power is applied on the Barrel Jack, all power is provided by the USB-C Connectors
