Epson Power Supply S1F70000 - Manual (Page 179)

S1F71100 Series
4–34 EPSON
S1F70000 Series
Technical Manual
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.
FEATURES
• Input voltage : 3.3V ~ 12V
• Output voltage : 3.3V (S1F71100M0A0)
• Power off current : 1
µ
A
• Self current consumption : 800
µ
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.
BLOCK DIAGRAM
+
–
+
–
V DD
POFFX
I SENSE
SWO
V SS
SSCAP
V O
ERCAP
Low-voltage
protection circuit
Reference
voltage circuit
Soft start Oscillator
PWM circuit
Error amplifier
Driver
Overcurrent
protection circuit
–
+
S1F71100 Series PWM Type Step-down DC/DC Switching Regulator