Rev.1.0

HIGH OPERATING VOLTAGE CMOS VOLTAGE REGULATOR

S-812C Series

Seiko Instruments Inc.

9

„Application Circuits

1. Output Current Boost Circuit

As shown in Figure 11, the output current

can be boosted by externally attaching a

PNP transistor.

The S-812C controls the

base current of the PNP transistor so that the

specified in the S-812C if the sufficient base-

transistor is obtained between input voltage

• As the transient response characteristics

of the circuit shown in figure 11 is not enough in some applications, evaluation for output variation due to

power-on, power line variation and load variation in actual condition is needed before massproduction.

• Note that the short-circuit protection incorporated in the S-812C series does not work as a short-circuit

protection for the boost circuit.

2. Constant Current Circuit

The S-812C series can be served in a

constant current circuit as shown in the

from the following equation:

the effective output voltage.

Please note that in case of the circuit

shown in the figure 12 (1) the magnitude of

driving ability of the S-812C.

The circuit shown in the figure 12 (2) can,

however, provide the current beyond the

driving ability of the S-812C by combining a

constant current circuit with a current boost

circuit. The maximum input voltage for the

constant current circuit is the sum of the

recommended

to

attach

a

capacitor

between the S-812C power source VIN

and VSS pins or between output VOUT

and VSS pins because rush current flows

at power-on.

3. Output Voltage Adjustment Circuit

can be calculated using the following equation;

÷ R1 + R2 x I

R1

Tr1

GND

VOUT

ON/OFF

VIN

VSS

Figure 11 Output Current Boost Circuit

S-812C

Series

I

(2) Constant Current Boost Circuit

Figure 12 Constant Current Circuits

R1

GND

Device

RL

VIN

VOUT

V0

VSS

S-812C

Series

Tr1

GND

Device

RL

VOUT

VIN

V0

VSS

(1) Constant Current Circuit

S-812C

Series

o

ON/OFF

ON/OFF