Power Management
A A
MICROELECTRONICS
GM432
1.24V ADJUSTABLE PRECISION SHUNT REGULATORS
TYPICAL APPLICATION CIRCUIT
Notes:
1. Set V
according to the following equation:
OUT
R1
V
OUT
= V
REF
( 1 +
)+ I
R1
REF
R2
R
V
V
IN
OUT
2. Choose the value for R as follows:
R1
The maximum limit for R should be such that the cathode current, I , is greater
K
than the minimum operating current (80µA) at V
*
IN(MIN)
V
GM432
REF
The minimum limit for R should be such that the cathode current, I , does not
K
exceed 100mA under all load conditions, and the instantaneous turn-on value
R2
for I does not exceed 150 mA. Both of the following conditions must be met:
K
V
IN(max)
GND
Rmin
(to limit instantaneous turn-on I )
K
150mA
V
-V
IN(max) OUT
Rmin
(to limit I under normal operating conditions)
K
I
+100mA
OUT(min)
Typical Performance Characteristics
200
175
150
125
100
75
15
V
=V
REF
V
=V
KA
KA
REF
T
=25°C
T
=25 C
A
A
10
5
I
min
50
0
25
0
-5
-25
-50
-1
-10
-2
-0.5
0
0.5
1
1.5
-1
0
0.5
1
1.5
Cathode Voltage(V)
V
Cathode Voltage (V)
KA
Figure 10. Cathode Current vs.
Cathode Voltage
Figure 9. Cathode Current vs.
Cathode Voltage
250
200
150
100
50
1.2440
1.2420
1.2400
1.2380
1.2360
1.2340
I
=10 mA
I
=10 mA
K
K
R1=10KW
R2= Open
0
0
10
20 30
40 50 60 70
0
10 20
30 40 50
60 70
T , Junction Temperature - C
J
T , Junction Temperature - C
J
Figure 12. Ref. Input Current vs.
Junction Temperature
Figure 11. Ref. Voltage vs. Junction
Temperature
7