TPS25751: returns to PTCH mode a few seconds after patch download

Tool/software:

Hello,

I am working with a TPS25751 device and an external STM32 microcontroller as I²C master. I am attempting to download the generated patch binary to the TPS25751 over I²C.

Problem description:

• The patch binary upload completes successfully.

• The device initially enters APP mode.

• After approximately three seconds, the device automatically switches back to PTCH mode.

Test details:

• Patch binary was generated with the USB PD Application Customization Tool.

• Transfer is performed using I²C burst download from the STM32 host.

• After upload I poll the registers once per second.

• Attached is the register dump captured every second after the patch download completes.

Observed behavior:

• Immediately after upload the device reports APP mode.

• Within ~3 seconds, the device reverts to PTCH mode.

• Register dumps attached show the transition.

Question:

• What conditions cause the TPS25751 to revert from APP mode to PTCH mode after a seemingly successful patch load?

Thank you for your support.

Iteration 0 (time = 187609 ms)

Mode                  (0x03): 41 50 50 20   ("APP ")
Customer Use          (0x06): 78 56 34 12 F0 DE BC 9A
Command               (0x08): 00 00 00 00
Data                  (0x09): 00 00 00 00 01 02 05 B1 0F 6A 7B C8 C2 29 98 47 AD ...
Interrupt Event       (0x14): 00 00 00 00 00 00 00 00 00 00 00
Interrupt Mask        (0x16): 00 00 00 00 00 00 00 00 00 00 03
Interrupt Clear       (0x18): 00 00 00 00 00 00 00 00 00 00 00
Status                (0x1A): 20 00 00 00 00
Power Path Status     (0x26): 00 00 00 00 40
Port Control          (0x29): 72 50 80 00
Boot Flags            (0x2D): 30 03 F0 C2 C1
...
Type C State          (0x69): 00 00 00 67
Sleep Control         (0x70): 02
GPIO Status           (0x72): 00 00 00 00 0C 0C 00 00

Iteration 1 (time = 188776 ms)

Mode                  (0x03): 41 50 50 20   ("APP ")
Customer Use          (0x06): 78 56 34 12 F0 DE BC 9A
Command               (0x08): 00 00 00 00
Data                  (0x09): 00 00 00 00 01 02 05 B1 0F 6A 7B C8 C2 29 98 47 AD ...
Status                (0x1A): 00 00 00 00 00
Power Path Status     (0x26): 00 00 00 00 40
Boot Flags            (0x2D): 30 03 F0 C2 C1
Type C State          (0x69): 00 00 00 66
Sleep Control         (0x70): 02
GPIO Status           (0x72): 00 00 00 00 0C 0C 00 00

Iteration 2 (time = 189943 ms)

Mode                  (0x03): 41 50 50 20   ("APP ")
Customer Use          (0x06): 78 56 34 12 F0 DE BC 9A
Command               (0x08): 00 00 00 00
Data                  (0x09): 00 00 00 00 01 02 05 B1 0F 6A 7B C8 C2 29 98 47 AD ...
Status                (0x1A): 00 00 00 00 00
Power Path Status     (0x26): 00 00 00 00 40
Boot Flags            (0x2D): 30 03 F0 C2 C1
Type C State          (0x69): 00 00 00 67
Sleep Control         (0x70): 02
GPIO Status           (0x72): 00 00 00 00 0C 0C 00 00

Iteration 3 (time = 191110 ms)

Mode                  (0x03): 50 54 43 48   ("PTCH")
Command               (0x08): 00 00 00 00
Data                  (0x09): 00 00 00 00 ... (all zeroes)
Interrupt Event       (0x14): 00 00 00 00 00 00 00 00 00 00 02
Interrupt Mask        (0x16): 00 00 00 00 00 00 00 00 00 00 02
Interrupt Clear       (0x18): 00 00 00 00 00 00 00 00 00 00 02
Power Path Status     (0x26): 00 00 00 00 00
Boot Flags            (0x2D): 30 03 60 02 C1

Iteration 4 (time = 192252 ms)

Mode                  (0x03): 50 54 43 48   ("PTCH")
Command               (0x08): 00 00 00 00
Data                  (0x09): 00 00 00 00 ... (all zeroes)
Interrupt Event       (0x14): 00 00 00 00 00 00 00 00 00 00 02
Interrupt Mask        (0x16): 00 00 00 00 00 00 00 00 00 00 02
Interrupt Clear       (0x18): 00 00 00 00 00 00 00 00 00 00 02
Power Path Status     (0x26): 00 00 00 00 00
Boot Flags            (0x2D): 30 03 60 02 C1