Functional descriptions, Epson – Epson Power Supply S1F70000 User Manual
Page 110
S1F78100Y Series
S1F70000 Series
EPSON
3–3
Technical Manual
S1F78100Y
Series
FUNCTIONAL DESCRIPTIONS
S1F78100Y Series is a fixed positive output type volt-
age regulator of series regulator system and is fitted
with an output control MOS transistor between the in-
put and output pins as shown in the figure below. The
voltage regulator feeds back voltages (V
REG
) divided
with the built-in resistors R
1
and R
2
connected between
V
DD
(2pin)
V
SS
(1pin)
V
O
(3pin)
R2
R1
V
REF
+
–
(V
REG
)
(Output control transistor)
(Operational amplifier)
the output pin (V
O
pin) and the V
SS
pin to compare
them with the reference voltage (V
REF
) and outputs the
stable output voltage (V
0
) not depending on input volt-
age by controlling the gate voltage of the output control
transistor. The output voltage is fixed inside and is de-
cided with the following formula:
V
O
=
R
1
+R
2
·V
REF
R
1