ZHCSTM4A October 2023 – March 2024 TPS25751
PRODUCTION DATA
When configured as a source, the TPS25751 detects when a cable or a Sink is attached using the CC1 and CC2 pins. When in a disconnected state, the TPS25751 monitors the voltages on these pins to determine what, if anything, is connected. See USB Type-C Specification for more information.
Table 8-1 shows the Cable Detect States for a Source.
CC1 | CC2 | CONNECTION STATE | RESULTING ACTION |
---|---|---|---|
Open | Open | Nothing attached | Continue monitoring both CCy pins for attach. Power is not applied to VBUS or VCONN. |
Rd | Open | Sink attached | Monitor CC1 for detach. Power is applied to VBUS but not to VCONN (CC2). |
Open | Rd | Sink attached | Monitor CC2 for detach. Power is applied to VBUS but not to VCONN (CC1). |
Ra | Open | Powered Cable-No UFP attached | Monitor CC2 for a Sink attach and CC1 for cable detach. Power is not applied to VBUS or VCONN (CC1). |
Open | Ra | 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). |
Ra | Rd | 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. |
Rd | Ra | 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. |
Rd | Rd | Debug Accessory Mode attached | Sense either CCy pin for detach. |
Ra | Ra | 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.