SABRE-LL-I datasheet(86/141 Pages) STMICROELECTRONICS

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Low voltage power switches

SABRE-LL-I

86/141

Low voltage power switches

18.1

Overview

Low voltage power switches are analog switches designed to operate from a single +2.4V to

+3.6V VGPIO_SPI supply. They are intended to provide and remove power supply to low

voltage devices. When switched on, they connect the VGPIO_SPI pin to their output pin

(GPIO[6] for low voltage power switch 1 or GPIO[7] for low voltage power switch 2) thus

powering the device connected to it. The turning on and off of each switch can be controlled

through serial interface.

S.A.B.Re provides a total of 2 low voltage power switches, each of them has current

limitation to minimum 150mA to limit inrush current when charging a capacitive load. When

the limit current has been reached, for more than a Tfilter time, then a flag is activated; this

flag is latched in the central logic and can be cleared by the firmware. Please note that, in

case of capacitive load, the current limit is reached the first time the low power switch is

turned on: therefore the user will find a limit flag that must be cleared.

The 2 low voltage power switches can be externally paralleled to obtain a single super low

voltage power switch. Low voltage pass switches sink current IPASS needed for their

functionality from pin VGPIO_SPI, they never inject current on this pin.

Figure 25.

Low power switch block diagram

EnLowVSw[x]

GPIO[6] (LPS 1)

GPIO[7] (LPS 2)

Current

Limit

Sensor

VGPIO_SP

LowVSwIlim[x]

To SPI

LowVSwIlimLth[x]

ClrLowVrSwLth

Reset Stat

GPIO[6]/GPIO[7]

Driver

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