SLVSD02E March 2015 – August 2021 TPS65982
The Primary and Secondary Detection follow the USB BC1.2 specification. This detection scheme looks for a resistance between D+ and D– lines by forcing a known voltage on the first line, forcing a current sink on the second line and then reading the voltage on the second line using the general purpose ADC integrated in the TPS65982. To provide complete flexibility, 12 independent switches are connected to allow firmware to force voltage, sink current, and read voltage on any of the C_USB_TP, C_USB_TN, C_USB_BP, and C_USB_BN. The left and right sections of Figure 9-39, the voltage source VDX_SRC and the current source IDX_SNK, are activated during primary and secondary detection.