HIGH RIPPLE-REJECTION LOW DROPOUT MIDDLE OUTPUT CURRENT CMOS VOLTAGE REGULATOR
Rev.3.2_00
S-1132 Series
Operation
1. Basic operation
Figure 13 shows the block diagram of the S-1132 Series.
The error amplifier compares the reference voltage (Vref) with Vfb, which is the output voltage resistance-divided by
feedback resistors Rs and Rf. It supplies the output transistor with the gate voltage necessary to ensure a certain
output voltage free of any fluctuations of input voltage and temperature.
VIN
*1
Current
Error
supply
amplifier
VOUT
−
Vref
Rf
+
Vfb
Reference
voltage circuit
Rs
VSS
*1. Parasitic diode
Figure 13
2. Output transistor
The S-1132 Series uses a low on-resistance P-channel MOS FET as the output transistor.
Be sure that VOUT does not exceed VIN + 0.3 V to prevent the voltage regulator from being damaged due to inverse
current flowing from the VOUT pin through a parasitic diode to the VIN pin.
Seiko Instruments Inc.
13
SII [ SEIKO INSTRUMENTS INC ]
