S-8327 Seiko, S-8327 Datasheet - Page 2

• Manufacturer Part Number: S-8327
• Description: (S-8323 / S-8327) SMALL PACKAGE PWM CONTROL STEP-UP SWITCHING REGULATOR
• Manufacturer: Seiko

Features
























Block Diagram
SMALL PACKAGE PWM CONTROL
STEP-UP SWITCHING REGULATOR
Low voltage operation: 0.9 V (I
Low current consumption :
Duty ratio:
External parts: coil, diode, and capacitor only
Output voltage: accuracy of ±2.4%
Soft start function: 6 msec (typ.)
Shutdown function
External transistor type is available (S-8327 Series)
SOT-23-5 small plastic package
SOT-23-3 small plastic package
SOT-89-3 miniature power molded plastic package
Step-down and voltage-inverting type are available.
(1) S-8323 Series
During operation: 17.2 A (typ.)
During shutdown : 0.5 A (max.)
Built-in PWM control circuit
CONT
(ON / OFF)
Soft start circuit
(a transistor is needed for the S-8327 Series.)
PWM
control
circuit
(V
OUT
= 3 V, 50 kHz)
OUT
= 1mA)
+
VREF
-
V
OUT
The S-8323/8327 Series is a CMOS PWM-control step-up switching
regulator which mainly consists of a reference voltage source, an
oscillation circuit, a power MOS FET (for S-8323 Series) , and an error
amplifier. The new PWM control circuit automatically changes the duty
ratio from 0% to 83% according to the current load, offering products of
a wide range, high efficiency. A step-up switching regulator is
constructed by externally connecting only a coil, a capacitor and a diode
to the S-8323 Series. This feature, along with its small package and low
current consumption, makes the S-8323 Series ideal for the power
supply of portable equipment. For applications requiring a high output
current, products used with an external transistor (S-8327 Series) are
also available.
Seiko Instruments Inc.
Figure 1 Block Diagram
V
SS


Applications






(2) S-8327 Series
pagers, handy calculators, and remote controllers
Constant voltage power supplies for cameras,
video equipment, and communications equipment
Power supply for microcomputers
Power supplies for portable equipment such as
EXT
(ON / OFF)
Soft start circuit
S-8323/8327 Series
PWM
control
circuit
+
-
VREF
V
OUT
V
SS
1