ST5481 datasheet(7/18 Pages) STMICROELECTRONICS

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ST5481

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7 - POWER MANAGEMENT

The device can be supplied by the USB bus

power lines VBUS (5 volts) and GNDBUS

(ground). This is enabled when RPSM (remote

power supply mode) is at logic one. Then on-chip

regulators bring 3.3 volts to internal analog and

digital blocks. When RPSM is high, a supply is

brought to external devices through pins GNDD1,

VREGD1, GNDD2, VREGD2, GNDA, VREGA.

The power budgeting is done by the host when

initializing the pipe:

The

needed

information

(maximum

power

consumption) is adjusted through pins CFG0,

CFG1 and as well as RPSM for “remote wake up

ability” information.

The following mechanism is used to do "a get

description device".

Figure 4 : Bus-Powered Mode (RPSM=1)

ST 5481

VBUS

RPSM

GNDBUS

VREGD1

GNDD1

VREGD2

GNDD2

VREGA

GNDA

From

To other

digital

analog

device

USB bus

Figure 5 : Self Powered Mode (RPSM=0)

ST 5481

VBUS

RPSM

GNDBUS

VREGD1

GNDD1

VREGD2

GNDD2

VREGA

GNDA

From

From 3.3V

externally

regulated

supplies

USB bus

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