HIGH RIPPLE-REJECTION AND LOW DROPOUT CMOS VOLTAGE REGULATOR

S-L2980 Series

Seiko Instruments Inc.

11

Operation

1. Basic Operation

Figure 11 shows the block diagram of the S-L2980 Series.

maintain the constant output voltage which is not influenced by the input voltage and temperature

change, to the output transistor.

*1

*1. Parasitic diode

VSS

Current

supply

−

+

VIN

VOUT

Error

amplifier

Reference

voltage

circuit

Figure 11

2. Output Transistor

In the S-L2980 Series, a low on-resistance P-channel MOS FET is used as the output transistor.

to inverse current flowing from the VOUT pin through a parasitic diode to the VIN pin.