The valid VBUS voltage range is defined from the VBUS nominal voltage by a high threshold voltage and a low

threshold voltage whose nominal values are respectively VBUS +5% and VBUS -5%. The nominal threshold limits

can be shifted by a fraction of VBUS from +1% to +15% for the high threshold voltage and from -1% to -15% for

the low threshold voltage. This means the threshold limits can vary from VBUS +5% to VBUS +20% for the high

limit and from VBUS-5% to VBUS -20% for the low limit.

The threshold limits are preset by default in NVM (see Section 8.3 Electrical and timing characteristics). The

threshold limits can be changed independently through NVM programming (see Section 6 Start-up configuration)

and also by software during attachment through the I²C interface.

3.3.2

VBUS discharge

The monitoring block also handles the internal VBUS discharge path connected to the VBUS_SENSE pin. The

discharge path is activated at detachment, or when the device goes into the error recovery state whatever the

power role (see Section 3.6 Hardware fault management).

The VBUS discharge path is enabled by default in NVM and can be disabled through NVM programming only (see

Section 6 Start-up configuration). The discharge time duration is also preset by default in NVM (see Section

8.3 Electrical and timing characteristics). The discharge time duration can be changed through NVM programming

(see Section 6 Start-up configuration) and also by software through the I²C interface.

3.3.3

VBUS power path assertion

The STUSB1702 can control the assertion of the VBUS power path on the USB Type-C port, directly or indirectly,

through the VBUS_EN_SRC pin.

The tables below summarize the configurations of the STUSB1702 and the operation conditions that determine

the electrical value of the VBUS_EN_SRC pin during system operations.

Table 5. Conditions for VBUS power path assertion in source power role

Pin

Electrical

value

Operation conditions

Comment

Type-C attached

state

VDD pin

monitoring

VBUS_SENSE pin monitoring

VBUS_EN_SRC

0

Attached.SRC or

UnorientedDebug

Accessory.SRC or

OrientedDebug

Accessory.SRC

VDD > UVLO if

VDD_UVLO

enabled and/or

VDD < OVLO if

VDD_OVLO

enabled

VBUS is within valid voltage

range if

VBUS_VALID_RANGE

enabled or

VBUS > UVLO if VBUS

_VALID_RANGE disabled

The signal is

asserted only if

all the valid

operation

conditions are

met

HiZ

Any other state

VDD < UVLO if

VDD_UVLO

enabled and/or

VDD > OVLO if

VDD_OVLO

enabled

VBUS is out ofvalid voltage

range if

VBUS_VALID_RANGE

enabled or

VBUS < UVLO if VBUS

_VALID_RANGE disabled

The signal is de-

asserted when

at least one non

valid operation

condition is met

As specified in the USB Type-C standard specification, the attached state “Attached.SRC” is reached only if the

voltage on the VBUS receptacle side is at vSafe0V condition when a connection is detected.

“Type-C attached state” refers to the Type-C FSM states as defined in the USB Type-C standard specification and

as described in the I²C register CC_OPERATION_STATUS.

“VDD pin monitoring” is valid only in source power role. Activation of the UVLO and OVLO threshold detections

can be done through NVM programming (see Section 6 Start-up configuration) and also by software through the

I²C interface. When UVLO and/or OVLO threshold detection is activated, VBUS_EN_SRC pin is asserted only if

the device is attached and the valid threshold conditions on VDD are met. Once the VBUS_EN_SRC pin is

asserted, the VBUS monitoring is done on VBUS_SENSE pin instead of the VDD pin.

STUSB1702

VBUS power path control

DS12664 - Rev 1

page 9/38