UPD301A

DS00002838B-page 20

 2018-2019 Microchip Technology Inc.

4.3.5

VCONN OPERATION

VCONN is a 5V supply that is used to power circuitry in the USB Type-C™ plug, which is required to implement Elec-

tronically Marked Cables. By default, the DFP always sources VCONN when connected to an active cable. However,

this may be changed by software.

APPLICATION NOTE:

It is not envisioned to ever enable both FETs simultaneously.

VCONN is monitored for an over current condition via an internal monitoring circuit. A VCONN over current condition is

recognized when the event persists for a time longer than specified.When an over-current VCONN event is detected,

an interrupt asserts. The device may be configured to automatically disable the VCONN FET upon detection of a CC1/

CC2 Back-Drive Error or VCONN Discharge Error. In the event of the detection of a debounced over-current VCONN

event, the enabled VCONN FET will be disabled.

4.3.6

VBUS DETECTION

The device implements a comparator for determining when VBUS is within a programmed range, vSafe5V, or vSafe0v.

VBUS is divided down externally via a 1:9 resistor divider to generate VBUS_DET_IN. VBUS_DET_IN is compared with

an 8-bit threshold generated by an integrated DAC.

Figure 4-2 illustrates the VBUS_DET_IN circuit. In a typical use case, VBUS_DET_IN thresholds are programmed to

track the following voltage ranges as defined in Table 4-5.

For a DFP, the VBUS comparator is useful to detect when VBUS is within the desired range per PD negotiations. This

is the case when VBUS is generated by a source external to the device.

For a UFP, the VBUS comparator is required to determine when a DFP is attached or detached. It may also use the

comparator to determine when VBUS is within a new voltage range negotiated via PD.

Note:

Table 4-5 illustrates the values of VBUS_DET_IN utilizing +/-1% accurate resistors where R1 is 10K Ohms

and R2 is 90 kOhms.

FIGURE 4-2:

VBUS_DET_IN COMPARATOR

Bandgap

Reference

VBUS_MATCH

DAC

VBUS

Threshold

Generation

10-bits

20 KHz Clock

VBUS_DET_IN

VBUS

R2

R1

R3

15 uA

ZTC