Other Parts Discussed in Thread: TPS25741, TPS25740,
I have the EVM connected to a tablet device for testing purposes. The device only accepts 5v and 20v profiles.
The EVM is setup as follows:
24v input
J3 set to H2 (20v @3A)
/EN12V link NOT fitted so NO V2 (No 12v)
J4 set to P2 (default 65W)
with this setup, the device will accept and charge at 20v as expected.
Here is a capture of the power delivery traffic. As you can see, PS_RDY is sent to the device after about 300mS from capabilities message send. All good..
If we now remove the /EN12v link on J3 to allow 12v to be offered we no longer get the PS_RDY message even though the device has not requested 12v, it has requested V3 (20v)
Here is the capture. As you can see the device performs a hard reset after about 500mS. This process cycles indefinitely.
I have scoped the EVM and the DC-DC is being set to 20v (20.62v) as expected when the device requests 20v but the TPS25741 does not seem to be sending the PS_RDY message when the 20v becomes stable.
Any ideas please
Trevor