TSU6721YFF

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SCDS345 – JUNE 2013

GENERAL OPERATION

The TSU6721 is a multimedia switch that connects a common USB connector to USB, UART or audio signals.

The device also has a MIC switch that connects to either VBUS or DP. It has an integrated load switch to support

charging. The load switch has OverVoltage Protection as well as OverCurrent Limiting Protection. In addition, the

TSU6721 also has an ID bypass switch to transmit ID signal from the connector to the host. It has an internal

FET switch that disconnects the coupling capacitor connected to the VBUS line.

Standby Mode

Standby mode is the default mode upon power up and occurs when no accessory has been detected. During this

mode, the VBUS and ID lines are continually monitored through comparators to determine when an accessory is

inserted. Power consumption is minimal during standby mode.

Load Switch

The integrated load switch provides both overvoltage/undervoltage and overcurrent limiting protection:

Overvoltage Protection

When the input voltage rises above VOVP, the internal load switch is turned off. The response is very rapid, with

the FET turning off in less than 1µs tOFF(OVP). The OVP_EN interrupt bit is set high when an overvoltage

condition is detected. When the input voltage returns below VOVP-VHYS_OVP and remains above VUVLO, the

VBUS switch is turned on again after a deglitch time of tON(OVP). This deglitch time ensures that the input

supply has stabilized before turning the switch on. When the OVP condition is cleared, the OVP_OCP_DIS

interrupt bit is set high.

Undervoltage Protection

When VBUS is not present and VBAT is less than 2.5V, VBAT and VBUS voltages are below the undervoltage

threshold and TSU6721 is powered off.

Overcurrent Limiting Protection

The TSU6721 also provides overcurrent limiting protection. When current increases beyond the IOCP threshold, a

time-out delay is initiated. After the delay has expired, and the current is still greater than IOCP, then load switch is

disabled. The maximum current that flows through the load switch is controlled by the IOCL limit. This feature

provides control on the VBUS charging current and minimizes the chance of internal circuitry damage caused by

overcurrent event. The overcurrent level can be programmed through I2C.

Power Supervisor

TSU6721 uses VBAT as the primary supply voltage. VBUS is the secondary supply. VDDIO is used for I2C

communication.

Table 1. Supply Voltage States

VBAT

VBUS

VDDIO

DETECTION

LOAD SWITCH

I2C

COMMENTS

Yes

No

No

Enabled

Not Enabled

Not Enabled

VBAT is supply

Yes

Yes

No

Enabled

Enabled

Not enabled

VBAT is supply. LOAD SWITCH controlled by

VBUS

Yes

No

Yes

Enabled

Not Enabled

Enabled

VBAT is supply

Yes

Yes

Yes

Enabled

Enabled

Enabled

VBAT is supply. LOAD SWITCH controlled by

VBUS

No

Yes

No

Enabled

Enabled

Not Enabled

VBUS is supply. LOAD SWITCH controlled by

VBUS

No

Yes

Yes

Not valid

No

No

Yes

Not valid

No

No

No

Power Down Reset

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