L4949 データシートの表示（PDF） - STMicroelectronics

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L4949

MULTIFUNCTION VERY LOW DROP VOLTAGE REGULATOR

STMicroelectronics 

L4949E

APPLICATION CIRCUIT

VBAT

VOUT

VZ (optional)

CT

VS

PREREGULATOR 5V

2µ

+

REG

SI

REF

RESET

VS

1.23V

SENSE

For stability: CS ≥ 1µF, CO ≥ 4.7µF, ESR < 10Ω at 10KHz

Recommended for application: CS = CO = 10µF to 100µF

2V

1.23V

D96AT219

RES

VOUT

SO

GND

APPLICATION INFORMATION

Supply Voltage Transient

High supply voltage transients can cause a reset

output signal disturbation.

For supply voltages greater than 8V the circuit

shows a high immunity of the reset output against

supply transients of more than 100V/µs.

For supply voltages less than 8V supply tran-

sients of more than 0.4V/µs can cause a reset

signal disturbation.

To improve the transient behaviour for supply

voltages less than 8V a capacitor at pin 3 can be

used.

A capacitor at pin 3 (C3 ≤ 1µF) reduces also the

output noise.

proach of this device allows to get easily also

other features and functions when required.

Voltage Regulator

The voltage regulator uses an Isolated Collector

Vertical PNP transistor as a regulating element.

Figure 1: Foldback Characteristic of VO

FUNCTIONAL DESCRIPTION

The L4949E is a monolithic integrated voltage

regulator, based on the STM modular voltage

regulator approch. Several outstanding features

and auxiliary functions are implemented to meet

the requirements of supplying microprocessor

systems in automotive applications. Nevertheless,

it is suitable also in other applications where the

present functions are required. The modular ap-

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