ZHCSFF4C February 2016 – August 2021 TPS65981
PRODUCTION DATA
The system is design to either operate bus-powered over Type-C/PD or line-powered from the DC barrel jack. The TPS65981 detects that the DC barrel jack is connected to GPIOn. In the simplest form, a voltage divider could be set to the GPIO I/O level when the DC Barrel jack voltage is present, as shown in Figure 10-4. A comparator circuit is recommend and used in this design for design robustness, as shown in Figure 10-5. Figure 10-3 shows the barrel jack detection circuitry used in the dock or monitor application connected to GPIO2 configured as an input.
This detect signal is used to determine if the barrel jack is present to support the 20 V PD power contracts and to hand-off charging from barrel jack to Type-C or Type-C to barrel jack. When the DC barrel jack is detected the TPS65981 at the Type-C port will not request power as a USB PD sink and the system will be able to support a 5-20 V source power contract to another device. When the DC Barrel Jack is disconnected the TPS65981 will exit any 20 V source power contract and re-negotiate a power contract as a sink. When the DC Barrel Jack is re-connected the TPS65981 will send updated source capabilities and re-negotiate a power contract if possible.