Description; Features; Block Diagram - Epson Power Supply IC S1F70000 Technical Manual

S1F71100 Series
S1F71100 Series PWM Type Step-down DC/DC Switching Regulator

DESCRIPTION

S1F71100 is a pulse width modulation (PWM) type
step-down DC/DC converter control IC for which the
CMOS process is used and to which a power transistor
is connected outside. S1F71100 is composed of an os-
cillator, a reference voltage circuit, an error amplifier, a
PWM circuit, a soft start circuit, a driver, etc. When this
IC drives an external P ch power MOS transistor,
S1F71100 can constitute a step-down DC/DC converter
that converts input voltages up to 12V into the output
voltage of 3.3V.
S1F71100 is also provided with a low-voltage protec-
tion circuit, an overcurrent protection circuit and a soft
start protection circuit. When receiving external sig-
nals, S1F71100 can stop the oscillator and the switching
circuit and turn off the power, so that it can reduce
wasteful current consumption at the time of system halt.

BLOCK DIAGRAM

POFFX
SSCAP
V
O
ERCAP
4–34
Reference
voltage circuit
Soft start
+
–
Error amplifier

FEATURES

• Input voltage : 3.3V ~ 12V
• Output voltage : 3.3V (S1F71100M0A0)
• Power off current : 1 A
• Self current consumption : 800 A
• Frequency fixing (200kHz) PWM
• Power off function (IC shutdown)
• Soft start function
• Overcurrent protection function
• Low-voltage protection function
• Shipping pattern : plastic package SOP4-8pin
* Radiation-resistant design has not been provided for
this specification.
V
DD
Low-voltage
protection circuit
+
–
Oscillator
PWM circuit
V
SS
EPSON
Overcurrent
protection circuit
–
+
Driver
S1F70000 Series
Technical Manual
I
SENSE
SWO