9

Communication interface

9.1

USB-PD protocol

The USB-PD module controls the USB Type-C™ connector signals and power delivery on Vbus line using

USB-PD protocol.

The ST-ONEMP device can provide an output voltage between 3.3 V to 21 V. The PDOs or APDOs used in the

application can be defined by the user (except for the mandatory 5 V).

The module provides the USB-PD Source layers over one power channel. This is the list of the USB-PD options

available on the ST-ONEMP USB-PD firmware stack embedded on the device.

The USB-PD module supports:

•

One USB-PD power SOURCE channel (DFP - AC adapter)

•

USB-PD REV 3.1 specification

•

PPS (Programmable Power Supply) with Constant Current mode

•

1 default PDO plus 6 slots for PDOs or APDOs, customer configurable

•

6 slots for PDOs or APDOs, customer configurable, to be used when a second port is attached (see

Section 9.1.8 )

•

Vconn source with 100 mW output power used to identify Electronically Marked Cables

•

Send Alert on OTP and OCP protections

•

Send Source_Capability_Extended message

The USB-PD module does NOT support:

•

Constant power on PPS mode

•

Communication via USB (D+/D- and or SSTx+/- and SSRx+/-)

•

Fast Role Swap

•

VDM message management apart from SVDM-SOP’ to manage the cable discovered

•

Battery Supply PDO and Variable Supply PDO

•

Power Sharing

•

Unchunked message

•

Type C authentication 1.0 extension

•

Firmware update using 1.0 extension

9.1.1

USB-PD Physical layer

The device includes a complete physical layer for USB-PD applications.

The CC pins can withstand up to 24 V, requiring no extra protection to manage accidental shorts to Vbus.

9.1.1.1

CC Pins Vconn

The IC includes an internal switch between CC1/2 and SVCC which is used to provide the VCONN for

electronically marked cable detection. The Vconn switch is current limited to avoid damaging the IC in case

of short on CC pins.

As required by the USB-PD standard, the CC pins include an integrated bleeder resistor with value RCCBLD which

is turned on for 10 ms when the Vconn is removed.

The CC Vconn directly connects the CC1 or CC2 pin to the SVCC voltage, so it can be used only when the

regulated voltage is 5 V, as during the Electronically Marked Cable detection.

9.1.1.2

CC OV comparator

The CC pins include a comparator to detect abnormal voltages on the pins caused, for example, by shorts to

Vbus. When the voltage on one of the CC pins bypasses VCCOVP the load switch is turned off, and normal

operation restarts only once the voltage on the pins drops below 2.5V

ST-ONEMP

Communication interface

DS13989 - Rev 2

page 28/39