UCS1001 datasheet(41/59 Pages) MICROCHIP

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USB Port Power Controller with Charger Emulation

Datasheet

SMSC UCS1001

Revision 1.2 (05-21-12)

DATASHEET

Chapter 7 Detect State

7.1

Device Attach / Removal Detection

The UCS1001 can detect the attachment and removal of a portable device on the USB port. Attach

and Removal Detection does not perform any charger emulation or qualification of the device. The

high-speed switch is “off” during the Detect power state.

7.2

VBUS Bypass Switch

In the Detect state, VDD is the voltage source; in the Active state, VS is the voltage source. The

bypass switch and the port power switch are never both on at the same time.

While the VBUS bypass switch is active, the current available to a portable device will be limited, and

the Attach Detection feature is active.

7.3

Attach Detection

The Attach Detection feature is only active in the Detect power state. When active, this feature

constantly monitors for portable device attachment. When an Attach Detection event occurs, the

UCS1001-2 will assert the A_DET# pin low. The UCS1001-1 internally flags the event.

Once an Attach Detection event occurs, the UCS1001 will wait for the PWR_EN control to be enabled

(if not already). When PWR_EN is enabled and VS is above the threshold, the UCS1001 will activate

the USB port power switch and operate in the selected Active mode (see Chapter 8, Active State).

7.4

Removal Detection

The Removal Detection feature will be active in the Active and Detect power states if S0 = 1. This

feature monitors for portable device removal.

When a Removal Detection event is flagged, the following will be done:

1. Disable the port power switch and the bypass switch.

2. De-assert the A_DET# pin (UCS1001-2 only).

3. Enable an internal discharging device that will discharge the VBUS line.

4. Once the VBUS pin has been discharged, the device will return to the Detect state regardless of

the PWR_EN control state.

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