Typical Performance Characteristics: continued
Quiescent Current vs. Output Current Over Temperature
Output Voltage and Supply Current vs. Input Voltage
3.5
3.0
22.0
20.0
5.5
5.0
VOUT
-40°C
2.5
2.0
1.5
1.0
0.5
0.0
4.0
3.0
2.0
16.0
25°C
12.0
8.0
4.0
0.0
IQ
125°C
1.0
0.0
VIN = 14V
0.1
0.0
2.0
4.0
6.0
8.0
10.0
0
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Supply Voltage
I
OUT
RESET Output Voltage vs. Output Current
2000
1800
1600
1400
1200
1000
800
V
= 5V
IN
600
400
200
0
1
5
10
15
20
25
30
35
40
Reset Output Current (mA)
Circuit Description
The NPN pass device prevents deep saturation of the output
stage which in turn improves the ICÕs efficiency by prevent-
ing excess current from being used and dissipated by the IC.
Voltage Reference and Output Circuitry
Precision Voltage Reference
The regulated output voltage depends on the precision
band gap voltage reference in the IC. By adding an error
amplifier into the feedback loop, the output voltage is
maintained within ±4% over temperature and supply vari-
ation.
Output Stage Protection
The output stage is protected against overvoltage, short
circuit and thermal runaway conditions (Figure 2).
> 30V
V
IN
Output Stage
The composite PNP-
NPN output structure
VIN
V
OUT
(Figure 1) provides 1A
(typ) of output current
while maintaining a
low drop out voltage
(1.2V) and drawing lit-
tle quiescent current
I
OUT
(4mA).
Load
Dump
Short
Circuit
Thermal
Shutdown
VOUT
Figure 1. Composite Output Stage of the CS8121
Figure 2. Typical Circuit Waveforms for Output Stage Protection.
4
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
