UCS1001 datasheet(32/59 Pages) MICROCHIP

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USB Port Power Controller with Charger Emulation

Datasheet

Revision 1.2 (05-21-12)

SMSC UCS1001

DATASHEET

4.2.3

Back-voltage Detection

Whenever the following conditions are true, the port power switch will be disabled, the VBUS bypass

switch will be disabled, the high-speed data switch will be disabled, and a Back-voltage event will be

flagged. This will cause the UCS1001 to enter the Error power state (see Section 4.1.5, "Error State

Operation").

1. The VBUS voltage exceeds the VS voltage by VBV_TH and the port power switch is closed. The

port power switch will be opened immediately. If the condition lasts for longer than tMASK, then the

UCS1001 will enter the Error state. Otherwise, the port power switch will be turned on as soon as

the condition is removed.

2. The VBUS voltage exceeds the VDD voltage by VBV_TH and the VBUS bypass switch is closed.

The bypass switch will be opened immediately. If the condition lasts for longer than tMASK, then the

UCS1001 will enter the Error state. Otherwise, the bypass switch will be turned on as soon as the

condition is removed.

4.2.4

Back-drive Current Protection

If a portable device is attached that is self-powered, it may drive the VBUS port to its power supply

voltage level; however, the UCS1001 is designed such that leakage current from the VBUS pins to the

VDD or VS pins shall not exceed IBD_1 (if the VDD voltage is zero) or IBD_2 (if the VDD voltage exceeds

VDD_TH).

4.2.5

Under-voltage Lockout on VS

The UCS1001 requires a minimum voltage (VS_UVLO) be present on the VS pin for Active power state.

4.2.6

Over-voltage Detection and Lockout on VS

The UCS1001 port power switch will be disabled if the voltage on the VS pin exceeds a voltage

(VS_OV) for longer than the specified time (tMASK). This will cause the device to enter the Error state.

4.3

Discrete Input Pins

APPLICATION NOTE: If it is necessary to connect any of the control pins except the ILIM or SEL pins via a resistor

to VDD or GND, the resistor value should not exceed 100 k

 in order to meet the VIH and

VIL specifications.

4.3.1

ILIM Input

The ILIM input determines the initial ILIM setting, as shown in Table 6.1, "UCS1001 ILIM Selection".

4.3.2

SEL Input

The SEL pin selects the polarity of the PWR_EN control. If the SEL pin is high, the PWR_EN control

is active high enable. If the SEL pin is low, the PWR_EN control is active low enable. This pin state

is latched upon device power-up and further changes will have no effect on the PWR_EN control

polarity.

APPLICATION NOTE: If it is necessary to connect the SEL pin to ground via a resistor, a value less than 33k



must be used. If it is necessary to connect the SEL pin to VDD via a resistor, the pull-up

resistor may be any value up to 100 k

.

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