Part Number: TPS65981
Hello,
I have a custom design using the TPS65981 as a power source only. I have a variable DC/DC regulator controlled by GPIO5 to output 5V or 9V depending on the contract. GPIO5 is set up as open-drain. Only PP_HV is used for both voltages. When connecting a type C tablet to the device, a 9V contract is negotiated and input voltage goes up to 9V but VBUS stays at 0V and I get a high voltage warning. If I disable the 9V PDO, everything works perfectly.
Thanks in advance.
Hi Arnaud,
There are two things that can help your issue.
1. Change the mapped event you are currently using for GPIO5 from "Source PDOX negotiated truth table LSB" to "source PDO1 Negotiated". The truth table is typically used for individuals who want to use 4 different PDO's, but have a shortage of GPIO's so they use 2 instead of 4. Since you are only wanting to use one GPIO, there is no need for the truth table set up
2. We recommend that you do not control the resistors for the external DCDC via an open-drain internal to the TPS65981. This has been known to cause errors so we usually advise against it. instead, we suggest to control the resistor network connected to the feedback pin by a series of external FETs with the gate of each tied to a GPIO. Here's a quick drawing of what your setup would look like. This also how the TPS65981EVM is set up.
Let me know if you have any questions about the above information. If this helped answer your problem, please click This resolved my issue
