Hello -
My team and I are utilizing the TCPP02-M18 in combination with the TI TPS65987 USB-C Controller in a USB Power Provider application.
Right at the moment when a transition from the nominal 5V to a higher negotiated voltage occurs the TCPP02-M18 triggers an over-current fault and removes power from the Sink device. This is confirmed by reading the I2C registers of the TCPP02-M18 where Register 0x02 reports 0x82. When I clear the fault via the I2C writes the same cycle occurs.
If I short over the sense resistor, R21 in our schematic, the over-current fault doesn't occur. Page 9 of the UM2973 for the X-NUCLEO-SRC1M1 suggests that the drain-to-gate capacitance for the MOSFET must be greater than 20pF. I'm using the Vishay SQJQ904E-T1_GE3 as the dual N-Channel MOSFET in the provider path which has a gate capacitance of ~0.5nF to 1.5nF, so an additional capacitor should not be necessary.
The Sink device that I'm using in these tests on consumes ~20mA on the VBUS net, so we should be very far from any real overcurrent events. I do not see any transition events on the IANA output of the TCPP02-M18 that would indicate an overcurrent is actually occurring.
Below is a screenshot of the TCPP02-M18 portion of our schematic.
Do you have any guidance or suggestions on how to continue to debug this?
- Shane
