UCS81003 datasheet(28/108 Pages) MICROCHIP

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UCS81003

DS20005334A-page 28

 2014 Microchip Technology Inc.

5.1.1

OFF STATE OPERATION

The device is in the Off state if VDD is less than VDD_TH.

When the UCS81003 is in the Off state, it does nothing,

and all circuitry is disabled. Digital register values are

not stored and the device will not respond to SMBus

commands.

5.1.2

SLEEP STATE OPERATION

When the UCS81003 is in the Sleep state, the device

is in its lowest-power state. The high-speed switch,

bypass switch and the port power switch are disabled.

The Attach and Removal Detection feature is disabled.

VBUS will be near ground potential. The ALERT# pin is

not asserted. If asserted prior to entering the Sleep

state, the ALERT# pin will be released. The A_DET#

pin is released. SMBus activity is limited to single byte

read or write.

The first data byte read from the UCS81003 when in

the Sleep state will wake the device; however, the

data to be read will return all 0’s and should be

considered invalid. This is a “dummy” read byte meant

to wake the UCS81003. Subsequent read or write

bytes will be accepted normally. After the dummy

read, the UCS81003 will be in a higher-power state

(see Figure 5-6). The device will return to Sleep after

the

last

communication,

further

communication has occurred.

Figure 5-5 shows timing diagrams for waking the

UCS81003 via external pins. Figure 5-6 shows the

timing for waking the UCS81003 via SMBus.

FIGURE 5-5:

Wake Timing via External Pins.

FIGURE 5-6:

Wake via SMBus Read with S0 = ‘0’.

M1 or M2

Port power switch closed

(Active state)

tPIN_WAKE

Wake with M1 or M2 to Active State Data Pass-through Mode

(PWR_EN enabled, S0 = ‘0’,EM_EN = ‘0’,VS >VS_UVLO)

Bypass switch closed

(Detect state)

tPIN_WAKE

Wake with S0

(VS >VS_UVLO,M1&M2 &EM_EN not all ‘0’ and not set to Data Pass-through)

0101_111 0 A

invalid

data

SMBus Read

0001_0000

0101_111 0 A

valid data

0001_0000

tIDLE_SLEEP

Sleep

Dummy read returns invalid data

and places device in temporary

Active state

Read returns valid data

0101_111 1 A

Power State

temporary Active state

(not all functionality available)

tSMB_WAKE

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