L4909 データシートの表示（PDF） - STMicroelectronics

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L4909

EXTERNALLY ADJUSTABLE MULTIFUNCTION REGULATOR

STMicroelectronics 

L4909

EXTERNALLY ADJUSTABLE MULTIFUNCTION REGULATOR

s 3 OUTPUTS

- Vo1 : output voltage variable from 5 to 12 V;

limit current : 1.2 A.

- Vo2 : output voltage variable from 5 to 12 V;

limit current : 1.2 A.

- Vo3 : output voltage variable from 5 to 12 V;

limit current : 1.2 A.

s ENABLE INPUT FOR EACH REGULATOR

s FEEDBACK INPUT FOR EACH REGULATOR

s SHORT CIRCUIT PROTECTION TO GROUND

s OVERCURRENT WARNING

s DRIVER FOR EXTERNAL SCR (CROWBAR

PROTECTION)

s THERMAL SHUTDOWN

DESCRIPTION

It is a monolithic Multifunction Voltage Regulator; it

contains 3 regulators, (REG1, REG2, REG3) each

one with an enable input and a feedback input, to al-

low the voltage setting via external resistive divider.

BLOCK DIAGRAM

MULTIWATT 15

Each regulator is current limited and furthermore an

OR-ed warning signal is output (open collector, ac-

tive low output) when the current in a regulator goes

above an over-current threshold (1 A typ for any reg-

ulator).

When one output voltage is higher than 20% typ of its

nominal value (for instance in case of input-to-output

short circuit), the crowbar output pin is activated, trig-

gering an external SCR (connected between input

and ground) that blows the input line fuse.

6

EN1

7

EN2

9

EN3

+

THERMAL

SHUTDOWN

ENABLE

CONTROL

REFERENCE

GENERATOR

REF

REF+20%

REG1

REG2

REG3

-

+

+

5

OC

OVER

CURRENT

CHECK

-

+

4

TRIG

8

GND

-

+

+

REG1

-

+

REG2

-

+

REG3

-

+

3,13

+

VINA, VINB

2

VO1

1

FB1

+

14

VO2

15

FB2

+

11

VO3

10

FB3

D00AU1171

May 2000

1/7

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