Design Log DEC 012 u4 tps25750 replaced with tps25751drefr nrnd resolution - thepinkmile/Enigma-NG GitHub Wiki

DEC-012 - U4 TPS25750 Replaced with TPS25751DREFR (NRND Resolution)

  • Status: ✔ RESOLVED
  • Date: 2026-04-03
  • Category: Electrical
  • Area: Power Module U4, schematic, PCB footprint

Decision

Replace TPS25750 (NRND - Not Recommended for New Designs) with TPS25751DREFR (PD3.1 certified DRP controller, WQFN-38 6x4mm).

Rationale

  • PD emulation for U4 is required: the Raspberry Pi CM5 must negotiate a 5V/5A (25W) contract from the USB-C PD source to prevent the OS from issuing under-voltage warnings and throttling the system.

  • The TPS25751D variant includes the integrated 20V/5A bi-directional power path and a 5V/3A source switch in one package - appropriate for DRP operation that can advertise and deliver the 5V/5A

    profile to the CM5.

  • TPS25751 is USB-IF PD3.1 certified (TID#10306); TPS25750 was PD2.0 only and is NRND.

  • STUSB4500 (U5) handles the USB-C sink path; TPS25751 (U4) handles the source/emulation path. These are separate and complementary roles.

Impact

  • Package: TPS25750 was QFN-28; TPS25751DREFR is WQFN-38 6x4mm. KiCad symbol and footprint to be created when schematic capture begins.
  • Mouser: 595-TPS25751DREFR; DigiKey: 296-TPS25751DREFRCT-ND; JLCPCB: C30169739.