TUSB422 datasheet(16/71 Pages) TI1

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TUSB422

SLLSEW6 – NOVEMBER 2016

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Device Functional Modes (continued)

7.4.2 Active Mode

The TUSB422 is in the Active mode when either CC1_STATE field or CC2_STATE field in the CC Status register

are non-zero, the TCPM has completed the required Type-C debounce of CC pins, and the TCPM has set the

AUTO_DISCHARGE_DISCONNECT in the Power Control register. In active mode, all IOs are operational, and

VCONN is available for an active cable. The USB PD phy can be enabled in this mode by setting the Receiver

Detect Register to a non-zero value. The USB PD BMC PHY functionality can only be used if the TUSB422 is in

any of the following active states: Attached.SRC, Attached.SNK, DebugAccessory, or PoweredAccessory. Use of

TUSB422 USB PD BMC PHY in any other active state is not permitted.

7.4.3 Power Role Swap

Upon entering the active mode, the power provider and consumer is determined by whether or not TUSB422 is

presenting a Rp or a Rd on CC pins. If TUSB422 is presenting a Rp, then TUSB422 is a power provider. If

TUSB422 is presenting a Rd, then TUSB422 is a power consumer. Once in the active mode, it may become

necessary change power role through performing a power role swap. Key requirements for performing a power

role swap by the software are listed below. For additional details on power role swap, consult the USB PD

specification.

Transition from power provider to power consumer:

1. TCPM state machine needs to transition from Attached.SRC to Attached.SNK.

2. Disable VBUS source. TCPM should send DisableSourceVbus command to TUSB422 Command register.

3. Once VBUS is at vSafe0V, change Role Control register to present a Rd.

4. Upon reception of PS_RDY message from port partner, update message header information and send

PS_RDY back to port partner.

5. Enable Sink VBUS and VBUS presence detection. TCPM should send SinkVbus and EnableVbusDetect

commands to TUSB422 Command register.

Transition from power consumer to power provider:

1. Disable AUTO_DISCHARGE_DISCONNECT in the Power Control register

2. Disable VBUS presence detection. TCPM should send DisableVbusDetect command to TUSB422 Command

3. Disable system sink VBUS. TCPM should also send DisableSinkVbus command to TUSB422 Command

4. TCPM state machine needs to transition from Attached.SNK to Attached.SRC.

5. Upon reception of PS_RDY message from port partner, change Role Control register to present a Rp.

6. Enable system source VBUS. TCPM should send SourceVbusDefaultVoltage command to TUSB422

Command register.

7. Once VBUS is at vSafe5V, the TCPM should then send PS_RDY to its port partner.

8. Upon successful completion of power-role swap, enable AUTO_DISCHARGE_DISCONNECT in the Power

Control register

7.4.4 Debug Accessory

A Debug accessory is a device which presents Rd on both of TUSB422 CC pins or Rp on both of TUSB422 CC

pins. The TUSB422 upon detecting either of these two conditions on its CC pins performs the required Type-C

debounce.

either

condition

still

present

end

the

debounce,

the

TUSB422

sets

the

DEBUG_ACC_CONNECTED bit in the Power Status Register.

The TCPM is required to determine cable orientation by reading the CC1_STATE and CC2_STATE in the CC

Status register and writing the orientation to the PLUG_ORIENTATION bit in the TCPC Control register.

Table 3. DebugAccessory Attached as a Sink

CC1_STATE

CC2_STATE

TCPM Writes to PLUG_ORIENTATION bit

2’b10 (Rd)

2’b01 (Ra)

1’b0. PD communication over CC1

2’b01 (Ra)

2’b10 (Rd)

1’b1. PD communication over CC2

TUSB422 Datasheet(PDF) 16 Page - Texas Instruments

TUSB422 Datasheet(HTML) 16 Page - Texas Instruments

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