S-1121 Seiko Instruments, S-1121 Datasheet - Page 14

• Manufacturer Part Number: S-1121
• Description: (S-1111 / S-1121) HIGH RIPPLE-REJECTION LOW DROPOUT
• Manufacturer: Seiko Instruments

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14
HIGH RIPPLE-REJECTION LOW DROPOUT CMOS VOLTAGE REGULATOR
S-1111/1121 Series
Operation
2. Output transistor
1. Basic operation
Figure 11 shows the block diagram of the S-1111/1121 Series.
The error amplifier compares the reference voltage (V
divided by feedback resistors R
to ensure a certain output voltage free of any fluctuations of input voltage and temperature.
The S-1111/1121 Series uses a low on-resistance P-channel MOS FET as the output transistor.
Be sure that V
to inverse current flowing from VOUT pin through a parasitic diode to VIN pin.
*1. Parasitic diode
VSS
VIN
OUT
Current
supply
does not exceed V
Reference voltage
V
ref
circuit
s
and R
−
+
amplifier
IN
Seiko Instruments Inc.
Error
f
+ 0.3 V to prevent the voltage regulator from being damaged due
. It supplies the output transistor with the gate voltage necessary
Figure 11
ref
) with V
R
R
s
f
fb
, which is the output voltage resistance-
V
fb
*1
VOUT
Rev.4.1
_00