3.5

Data role and VCONN SWAP

The STUSB4761, as a source, can advertise itself as a data host or downstream facing port (DFP). In order to

respond to unstructured message, the STUSB4761 supports incoming data role swap requests from the sink.

When request is acknowledged (if DR_SW_EN = ON), the STUSB4761 becomes UFP.

In the same way, the STUSB4761 supports incoming VCONN swap request from the sink. When the request is

acknowledged, the port remains a source and the DFP/UFP roles remain unchanged.

3.6

Voltage and current regulation

3.6.1

Voltage regulation

Input voltage is sensed on VDD pin. Until a PD contract is negotiated, regulation is set to 5 V. In power delivery

mode, the regulation aligns VBUS value on negotiated voltage value. Voltage regulation accuracy is 3% worst

case.

3.6.2

CC MODE

VBUS current, used for regulation, is measured thanks to a 10 mOhms (default) shunt resistor between VDD

and ISENSE_DISCH pins. In case the measured VBUS current reaches the regulation threshold, the STUSB4761

enters constant current (CC) mode: voltage is decreased down to the undervoltage (UVLO) condition defined

for the selected contract if current does not decrease enough, which triggers the voltage monitoring alert; in this

case, the STUSB4761 goes to error-recovery (see Section 3.8 Hardware fault management).

PDO current can be adjusted from 300 mA up to 5 A.

•

Below 1 A, current regulation is effective about 130 mA or 260 mA (adjustable OCP threshold) above the

current set.

•

Above 1 A, current regulation is effective when the measured current overcomes by either 12.5% or 25%

(adjustable OCP threshold) the current regulation reference

When the STUSB4761 is attached in Type-C mode, current regulation threshold is set to the STUSB4761 Rp

value: TYPEC_CURRENT (see Section 4.1 Parameter overview).

When the STUSB4761 is attached in USB PD mode, current regulation reference is set by default to the current

value from the selected source PDO. Other configurations are possible as per table below:

Table 5. Reference regulation current

1

(DEFAULT)

Current from the STUSB4761 PDO selected by the sink:

I_SRC_PDO[RDO object position field]

2

Operating current of sink request:

RDO[operating current field]

3

Maximum operating current of sink request:

RDO[max. operating current field]

Table 6. OCP threshold

1

(DEFAULT)

12.5% above reference regulation current (1)

2

25% above reference regulation current(2)

1. If current > 1 A (otherwise +130 mA if current <1 A)

2. If current > 1 A (otherwise +260 mA if current <1 A)

In the other cases, the current regulation threshold is set to 300 mA:

•

At Power-On reset exit

•

When no sink device is attached

STUSB4761

Data role and VCONN SWAP

DS13141 - Rev 3

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