Rev.1.0
_10
SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR
S-8351/52 Series
The S-8351/8352 Series is a CMOS PFM-control step-up
switching regulator that mainly consists of a reference voltage
source, an oscillator, and a comparator. The PFM controller
allows the duty ratio to be automatically switched according to
the load (light load: 50%, high output current: 75%), enabling
products with a low ripple over a wide range, high efficiency, and
high output current (product types A, B, and D). Products with a
fixed duty ratio of 75% are also available (product type C).
With the S-8351 Series, a step-up switching regulator can be
configured by using an external coil, capacitor, and diode. The
built-in MOS FET is turned off by a protection circuit when the
voltage at the CONT pin exceeds the limit to prevent it from
being damaged. This feature, along with the mini package and
low current consumption, makes the S-8351 Series ideal for
applications such as the power supply unit of portable
equipment.
The S-8352 Series, which features an external transistor, is
suitable for applications requiring a high output current.
Features
Startup at 0.9 V min. (I
OUT
=
1 mA) guaranteed
During maximum operation: 23.2
µA
(V
OUT
=
3.3 V, typ.)
During shutdown: 0.5
µA
(max.)
•
Duty ratio:
50/75%, built-in auto-switching-type PFM controller (product types A, B, D)
75%, built-in fixed-type PFM controller (product type C)
•
External parts:
Coil, capacitor, diode
•
Output voltage:
Settable to between 2.0 to 6.5 V (product types A, B, C) or 1.5 to 6.5 V (product
type D) in 0.1 V steps, accuracy of
±2.4%
•
Shutdown function (product type A)
•
V
DD
/V
OUT
separate type (product type D)
•
External transistor type available (S-8352 Series)
•
Low voltage operation:
•
Low input current:
Packages
•
SOT-23-3 (package drawing code: MP003-A)
•
SOT-23-5 (package drawing code: MP005-A)
•
SOT-89-3 (package drawing code: UP003-A)
Applications
•
Power supply for portable equipment such as digital cameras, electronic notebooks, and PDAs
•
Power supply for audio equipment such as portable CD/MD players
•
Constant voltage power supply for cameras, video equipment, and communications equipment
•
Power supply for microcomputers
Seiko Instruments Inc.
1
SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR
S-8351/52 Series
Applications
1. Function List
Control System
Switching
Product Name (Duty Ratio (%)) Frequency (kHz)
S-8351AxxMC
S-8351BxxMA
S-8351CxxMA
S-8351CxxUA
S-8351DxxMC
S-8352AxxMC
S-8352BxxMA
S-8352CxxMA
S-8352CxxUA
S-8352DxxMC
PFM (50/75)
PFM (50/75)
PFM (75)
PFM (75)
PFM (50/75)
PFM (50/75)
PFM (50/75)
PFM (75)
PFM (75)
PFM (50/75)
100
100
100
100
100
100
100
100
100
100
Shutdown
Function
Yes
Yes
V
DD
/V
OUT
Separate Type
Yes
Yes
Power
MOS FET
Built-in
Built-in
Built-in
Built-in
Built-in
External
External
External
External
External
Package
SOT-23-5
SOT-23-3
SOT-23-3
SOT-89-3
SOT-23-5
SOT-23-5
SOT-23-3
SOT-23-3
SOT-89-3
SOT-23-5
Rev.1.0
_10
Application
Application requiring shutdown function
Application not requiring shutdown function
Application not requiring shutdown function
Application not requiring shutdown function
Application in which output voltage is
adjusted by external resistance
Application requiring shutdown function
Application not requiring shutdown function
Application not requiring shutdown function
Application not requiring shutdown function
Application in which output voltage is
adjusted by external resistance
2. Product Name
S-835 X X XX XX
−
XXX
−
T2
IC direction in tape specification
Product name
Package name
MA; SOT-23-3 (without shutdown function)
MC; SOT-23-5 (with shutdown function or V
DD
/V
OUT
separate type)
UA; SOT-89-3 (without shutdown function)
Output voltage
×
10 (15 for output voltage value 1.5)
Product type
A ; With shutdown function
B ; Automatic duty ratio switching type
C ; Duty ratio fixed type (75%)
D ; V
DD
/V
OUT
separate type
Series name
1; Built-in power MOS FET
2; External power MOS FET
2
Seiko Instruments Inc.
SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR
Rev.1.0
_10
3. Product Name List
Output Voltage
S-8351AxxMC
Series
3.0
3.3
3.5
5.0
5.5
S-8351A30MC-J2P-T2
S-8351A33MC-J2S-T2
S-8351A35MC-J2U-T2
S-8351A50MC-J3J-T2
S-8351A55MC-J3O-T2
S-8351/52 Series
S-8351BxxMA
Series
S-8351B30MA-J4P-T2
S-8351CxxMA
S-8351CxxUA
Series
S-8351DxxMC
Series
Output Voltage
S-8352AxxMC
Series
S-8352BxxMA
Series
S-8352CxxMA
S-8352CxxUA
Series
S-8352DxxMC
Series
S-8352D20MC-K8F-T2
2.0
3.0
5.0
Remark
above.
S-8352A30MC-K2P-T2 S-8352B30MA-K4P-T2
S-8352A50MC-K3J-T2
Please consult our sales staff if you require a product with an output voltage other than those specified
Seiko Instruments Inc.
3
SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR
S-8351/52 Series
Block Diagrams
(1) S-8351 Series A type (with shutdown function)
CONT
Protection
circuit
IC internal
power supply
Rev.1.0
_10
(2) S-8352 Series A type (with shutdown function)
VOUT
IC internal
power supply
VOUT
V
REF
V
REF
EXT
PFM
controller
PFM
controller
−
+
−
+
VSS
VSS
ON/OFF
ON/OFF
(3) S-8351 Series B, C type (without shutdown function)
CONT
Protection
circuit
(4) S-8352 Series B, C type (without shutdown function)
VOUT
IC internal
power supply
VOUT
IC internal
power supply
V
REF
V
REF
EXT
PFM
controller
PFM
controller
−
+
−
+
VSS
VSS
(5) S-8351 Series D type (V
DD
/V
OUT
separate type)
CONT
Protection
circuit
(6) S-8352 Series D type (V
DD
/V
OUT
separate type)
VDD
IC internal
power supply
VDD
VOUT
V
REF
+
VOUT
V
REF
+
IC internal power supply
PFM
controller
−
EXT
PFM
controller
−
VSS
VSS
Figure 1. Block Diagrams
4
Seiko Instruments Inc.
SMALL PACKAGE PFM CONTROL STEP-UP SWITCHING REGULATOR
Rev.1.0
_10
Pin Assignment
Top View
5
4
Top View
1
Top View
S-8351/52 Series
1
2
3
2
3
SOT-23-3
1
2
3
SOT-23-5
SOT-89-3
Figure 2. Pin Assignment
A type (with shutdown function)
PKG: SOT-23-5
Pin No.
Pin Name
Shutdown pin
“H”: Normal operation
1
ON/OFF
(step-up operating)
“L”: Step-up stopped
(entire circuit stopped)
2
3
4
VOUT
VSS
CONT
*1
5
EXT
*2
Output voltage pin and IC power
supply pin
(N.C.)
GND pin
External inductor connection pin
(S-8351 Series)
External transistor connection pin
(S-8352 Series)
3
Functions
B, C type (without shutdown function)
PKG: SOT-23-3
Pin No.
1
2
Pin Name
VOUT
VSS
CONT
*1
EXT
*2
Functions
Output voltage pin and IC power supply pin
GND pin
External inductor connection pin
(S-8351 Series)
External transistor connection pin
(S-8352 Series)
D type (V
DD
/V
OUT
separate type)
PKG: SOT-23-5
Pin No.
1
Pin Name
VOUT
Functions
Output voltage pin
IC power supply pin
(N.C.)
GND pin
External inductor connection pin
(S-8351 Series)
EXT
*2
External transistor connection pin
(S-8352 Series)
C type (without shutdown function)
PKG: SOT-89-3
Pin No.
1
2
Pin Name
VSS
VOUT
GND pin
Output voltage pin and IC power
supply pin
CONT
*1
3
EXT
*2
External inductor connection pin
(S-8351 Series)
External transistor connection pin
(S-8352 Series)
Functions
2
3
4
VDD
VSS
CONT
*1
5
*1.
*2.
Open-drain output
CMOS output
Seiko Instruments Inc.
5
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