SABRE-LL-I datasheet(35/141 Pages) STMICROELECTRONICS

35 / 141 page

SABRE-LL-I

Linear main regulator

35/141

Linear main regulator

11.1

Overview

The linear main regulator is directly powered by VSupply voltage and it is one of the

regulators that S.A.B.Re could consider as a system regulator. This means that the voltage

generated by this regulator is not used to power any internal circuit, but S.A.B.Re will check

that the feedback voltage VLINmain_FB is in the good value range before enabling all its

internal functions. When an under-voltage event (with a duration longer than period

Tlinear_uv defined by the deglitch filter) is detected during normal operation, S.A.B.Re will

enter in reset state and it will signal this event to the microcontroller by pulling low the

nRESET pin and disabling most of its internal blocks.

Here are summarized the primary features of the regulator:

–

Regulated output voltage from 0.8V to VSupply-2V with a maximum load of 10mA.

–

Band gap generated internal reference voltage.

–

Short circuit protected (output current is clamped to 22mA typ).

–

Under voltage signal (both continuous and latched) accessible through serial

interface.

–

Low power dissipation mode.

The internal series element is a P-channel MOS device. The voltage regulator will regulate

its output so that feedback pin equals VLINmain_FB, therefore the regulated voltage can be

calculated using the formula:

VLINmain_OUT = VLINmain_ref *(Ra+Rb)/Rb

Figure 7.

Linear main regulator

To extend the output current capability this regulator can be used as a controller for an

external active component able to provide higher current (i.e. a Darlington device); the

external power element allows the handling of an higher current since it dissipates the

VLINmain_ref

Body Diode

Vsupply

VLINmain_OUT

VLINmain_FB

SABRE-LL-I датащи(PDF) 35 Page - STMicroelectronics