SLVSH00 November 2024 TPD4S480
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
For this application, we want to support 240W dead battery operation; when the device is out of battery, we still want to charge the laptop at 48V and 5A. This means that the USB PD Controller must receive power in dead battery mode. The TPS26750 has a built in LDO to supply the TPS26750 power from VBUS in a dead battery condition.
The OVP FETs of the TPD4S480 remain OFF when unpowered to provide protection in dead battery or unpowered situations. However, when the OVP FETs are OFF, this isolates the TPS26750s dead battery resistors from the USB Type-C ports CC pins. A USB Type-C power adapter must see the RD pull-down dead battery resistors on the CC pins to provide power on VBUS. Since the dead battery resistors of the TPS26750 are isolated from the USB Type-C connector CC pins, the built-in, dead battery resistors of the TPD4S480 must be connected. Short the RPD_G1 pin to the C_CC1 pin, and short the RPD_G2 pin to the C_CC2 pin.
Once the power adapter sees the dead battery resistors of the TPD4S480, 5V is applied on the VBUS pin. This provides power to the TPS26750, turning the PD controller on, and allowing the battery to begin to charge. However, this application requires 240W charging in dead battery mode, so VBUS at 48V and 5A is required. USB PD negotiation is required to accomplish this, so the TPS26750 needs to be able to communicate on the CC pins. The TPD4S480 needs to be turned on in dead battery mode as well so the PD controller can be exposed to the CC lines. To turn on the device, the TPD4S480 is powered by the internal LDO of the TPS26750, the LDO_3V3 pin. When the TPS26750 receives power on VBUS, the TPD4S480 is turned on simultaneously.
The dead battery resistors of the PD controller also need to be present so the PD controller properly boots up in dead battery operation with the correct voltages on the CC pins.
Once this process has occurred, the TPS26750 can start negotiating with the power adapter through USB PD for higher power levels, allowing 240W operation in dead battery mode.
For more information on the TPD4S480 dead battery operation, see the CC Dead Battery Resistors Integrated for Handling the Dead Battery Use Case in Mobile Devices section of the data sheet.