TPS25751D datasheet(37/89 Pages) TI1

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Table 8-1. Cable Detect States for a Source (continued)

CC1

CC2

CONNECTION STATE

RESULTING ACTION

Open

Powered Cable-No UFP

attached

Monitor CC1 for a Sink attach and CC2 for cable detach. Power is not applied to

VBUS or VCONN (CC1).

Powered Cable-UFP Attached

Provide power on VBUS and VCONN CC1) then monitor CC2 for a Sink detach.

CC1 is not monitored for a detach.

Powered Cable-UFP attached

Provide power on VBUS and VCONN (CC2) then monitor CC1 for a Sink detach.

CC2 is not monitored for a detach.

Debug Accessory Mode

attached

Sense either CCy pin for detach.

Audio Adapter Accessory

Mode attached

Sense either CCy pin for detach.

When a TPS25751 port is configured as a Source, a current IRpDef is driven out each CCy pin and each pin is

monitored for different states. When a Sink is attached to the pin, a pulldown resistance of Rd to GND exists.

The current IRpDef is then forced across the resistance Rd, generating a voltage at the CCy pin. The TPS25751

applies IRpDef until it closes the switch from PP5V to VBUS, at which time application firmware can change to

IRp1.5A or IRp3.0A.

When the CCy pin is connected to an active cable VCONN input, the pulldown resistance is different (Ra). In this

case, the voltage on the CCy pin lowers the PD controller recognizes it as an active cable.

The voltage on CCy is monitored to detect a disconnection depending upon which Rp current source is active.

When a connection has been recognized and the voltage on CCy subsequently rises above the disconnect

threshold for tCC, the system registers a disconnection.

8.3.4.2 Configured as a Sink

When a TPS25751 port is configured as a Sink, the TPS25751 presents a pulldown resistance RSNK on each

CCy pin and waits for a Source to attach and pull up the voltage on the pin. The Sink detects an attachment by

the presence of VBUS and determines the advertised current from the Source based on the voltage on the CCy

pin.

8.3.4.3 Configured as a DRP

When a TPS25751 port is configured as a DRP, the TPS25751 alternates the CCy pins of the port between the

pulldown resistance, RSNK, and pullup current source, IRp.

8.3.4.4 Dead Battery Advertisement

The TPS25751 supports booting from no-battery or dead-battery conditions by receiving power from VBUS.

Type-C USB ports require a sink to present Rd on the CC pin before a USB Type-C source provides a voltage

on VBUS. TPS25751 hardware is configured to present this Rd during a dead-battery or no-battery condition.

Additional circuitry provides a mechanism to turn off this Rd once the device no longer requires power from

VBUS.

8.3.5 Overvoltage Protection (CC1, CC2)

The TPS25751 detects when the voltage on the CC1 or CC2 pin is too high or there is reverse current into

the PP5V pin and takes action to protect the system. The protective action is to disable PP_CABLE within

tPP_CABLE_FSD and disable the USB PD transmitter.

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TPS25751

SLVSH93 – OCTOBER 2023

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