L4909 Datasheet, PDF (1/7 Pages) STMicroelectronics – EXTERNALLY ADJUSTABLE MULTIFUNCTION REGULATOR

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
+
V_INA, V_INB
2
V_O1
1
FB1
+
14
V_O2
15
FB2
+
11
V_O3
10
FB3
D00AU1171
May 2000
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