ST L4909 User Manual
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L4909
EXTERNALLY ADJUSTABLE MULTIFUNCTION REGULATOR
■
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.
■ ENABLE INPUT FOR EACH REGULATOR
■
FEEDBACK INPUT FOR EACH REGULATOR
■
SHORT CIRCUIT PROTECTION TO GROUND
■ OVERCURRENT WARNING
■
DRIVER FOR EXTERNAL SCR (CROWBAR
PROTECTION)
■ 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 allow the voltage setting via external resistive divider.
Each regulator is current limited and furthermore an
OR-ed warning signal is output (open collector, active low output) when the current in a regulator goes
above an over-current threshold (1 A typ for any regulator).
When one output voltage is higherthan 20% typ of its
nominal value (for instance in case of input-to-output
short circuit), the crowbar output pin is activated, triggering an external SCR (connected between input
and ground) that blows the input line fuse.
MULTIWATT15
BLOCKDIAGRAM
EN1
EN2
EN3
OC
TRIG
GND
May 2000
THERMAL
SHUTDOWN
6
7
9
5
4
8
ENABLE
CONTROL
OVER
CURRENT
CHECK
REFERENCE
GENERATOR
REG1
REG2
REG3
++
REF
REF+20%
+
+
+
+
+
+
REG1
-
REG2
-
REG3
-
+
3,13
+
+
14
15
+
11
10
D00AU1171
V
INA,VINB
2
V
O1
1
FB1
V
O2
FB2
V
O3
FB3
1/7
L4909
PIN CONNECTION
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
TAB CONNECTEDTO PIN 8
Table 1. Pin Description
No. Pin Name Function
1 FB1 REG1 feedback voltage input
2 Vo1 REG1 output voltage
3 VinA Input DC supply voltage
4 TRIG Trigger for external SCR (crowbar protection)
5 OC Over current warning output
6 EN1 REG1 enable input
7 EN2 REG2 enable input
8 GND Analog ground
9 EN3 REG3 enable input
10 FB3 REG3 feedback voltage input
11 Vo3 REG3 output voltage
12 N.C. Not Connected
13 VinB Input DC supply voltage
14 Vo2 REG2 output voltage
15 FB2 REG2 feedback voltage input
D00AU1153
FB2
V
O2
V
INB
N.C.
V
O3
FB3
EN3
GND
EN2
EN1
OC
TRIG
V
INA
V
O1
FB1
2/7
ABSOLUTEMAXIMUMRATINGS
Symbol Parameter Value Unit
Vin VinA,VinB input DC supply voltage 40 V
Io Vo1, Vo2, Vo3 output currents internally limited
Voc OC output voltage min (15, Vin) V
VENx ENx input voltage 15 V
Top Operating temperature range 0 to 70
Tstg Storage temperature - 40 to 150
THERMAL DATA
Symbol Parameter Value Unit
L4909
o
C
o
C
R
TH j-case
ELECTRICAL CHARACTERISTICS (C
Thermal Resistance Junction to Case 1.8 °C/W
= 100nF; Vin-Vo=5V;Io=10mA;T
out
=25°C unless otherwise
case
specified
Symbol Parameter Test Condition Min. Typ. Max. Unit
Vo1 REG1 output voltage range 5 12 V
V(FB1) REG1 feedback voltage EN1=ON; 1.22 1.27 1.32 V
Ilim1 REG1 output current limit EN1=ON; Vin-Vo1<12V 1.20 1.70 A
V
∆
-------------
V
∆ V
-------------
V
line regulation Io1=10mA; Vin-Vo1=3 to 25V
o1
o1
load regulation Io1=10 mA to 1.2A
o1
o1
Io1=10mA; Vin-Vo1=3 to 12V
Io1=10 mA to 0.5A
Vd1 REG1 drop out Io1=500mA 2.20 V
SVR1 REG1 supply voltage rejec. freq=120 Hz to 1KHz 60 dB
Vo2 REG2 output voltage range 5 12 V
V(FB2) REG2 feedback voltage EN2 = ON; 1.22 1.27 1.32 V
0.6
0.1
0.5
0.1
2%
2%
Ilim2 REG2 output current limit EN2=ON; Vin-Vo2<12V 1.20 1.70 A
∆ V
-------------
V
o2
∆ V
-------------
V
o2
line regulation Io2=10mA;Vin-Vo2=3 to 25 V
o2
load regulation Io2=10 mA to 1.2A
o2
Io2=10mA;Vin-Vo2=3 to 12 V
Io2=10 mA to 0.5A
0.6
0.1
0.5
0.1
2%
2%
Vd2 REG2 drop out Io2=500mA 2.2 V
3/7
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