S-8351/8352 Series
www.sii-ic.com
© Seiko Instruments Inc., 2002-2010
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING
REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0
_00
The S-8351/8352 Series is a CMOS step-up switching regulator controller which mainly consists of a reference voltage
source, an oscillation circuit, a comparator and PFM control circuit. The PFM control circuit allows the duty ratio to be
automatically switched according to the load (at light load : 50%, at high output current : 75%), enabling products with a low
ripple over a wide range, high efficiency, and high output current (A, B, and D type). Products with a fixed duty ratio of 75%
are also available (C type).
The S-8351 Series can configure a step-up switching regulator with an external coil, capacitor, and diode. A protection
circuit turns off the built-in MOS FET when the voltage at the CONT pin exceeds the limit to prevent it from being damaged.
In addition to the above features, the small 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
• Low voltage operation : Startup at 0.9 V min. (I
OUT
= 1 mA) guaranteed
• Low current consumption : During operation 23.2
μ
A (V
OUT
= 3.3 V, typ.)
During shutdown 0.5
μ
A (max.)
• Duty ratio : 50 % / 75 % built-in auto-switching-type PFM control circuit (A, B, and D type)
75 % built-in fixed-type PFM control circuit (C type)
• External parts : Coil, capacitor, and diode
• Output voltage : Selectable in 0.1 V steps between 2.0 V to 6.5 V (A, B, and C type)
Selectable in 0.1 V steps between 1.5 V to 6.5 V (D type)
• Output voltage accuracy :
±2.4%
• Shutdown function (A type)
• V
DD
/ V
OUT
separate type (D type)
• External transistor type available (S-8352 Series)
• Lead-free, Sn 100%, halogen-free
*1
*1.
Refer to “
Product Name Structure”
for details.
Applications
• Power supplies for portable equipment such as digital cameras, electronic notebooks, and PDAs
• Power supplies for audio equipment such as portable CD / MD players
• Constant voltage power supplies for cameras, video equipment, and communications equipment
• Power supplies for microcomputers
Packages
• SOT-23-3
• SOT-23-5
• SOT-89-3
Seiko Instruments Inc.
1
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0
_00
S-8351/8352 Series
Block Diagrams
1.
S-8351 Series
(1)
A Type (With shutdown function)
CONT
Protection
circuit
IC internal
power supply
V
REF
PFM
control
circuit
+
−
VOUT
VSS
ON / OFF
Figure 1
(2)
B and C Types (Without shutdown function, V
DD
/ V
OUT
non-separate type)
CONT
Protection
circuit
IC internal
power supply
V
REF
PFM
control
circuit
+
−
VOUT
VSS
Figure 2
(3)
D Type (V
DD
/ V
OUT
separate type)
CONT
IC internal power supply
Protection
circuit
PFM
control
circuit
+
−
V
REF
VDD
VOUT
VSS
Figure 3
2
Seiko Instruments Inc.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0
_00
S-8351/8352 Series
2.
S-8352 Series
(1)
A Type (With shutdown function)
VOUT
IC internal power supply
V
REF
PFM
control
circuit
+
−
EXT
VSS
ON / OFF
Figure 4
(2)
B and C Type (Without Shutdown function, V
DD
/ V
OUT
non-separate type)
VOUT
IC internal power supply
V
REF
PFM
control
circuit
+
−
EXT
VSS
Figure 5
(3)
D Type (V
DD
/ V
OUT
separate type)
VDD
IC internal
power supply
PFM
control
circuit
VOUT
V
REF
EXT
+
−
VSS
Figure 6
Seiko Instruments Inc.
3
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0
_00
S-8351/8352 Series
Product Name Structure
The product types, output voltage, and packages for the S-8351/8352 Series can be selected at the user’s request.
Please refer to the “3.
Product Name”
for the definition of the product name, “4.
Package”
regarding the package
drawings and “5.
Product Name List”
for the full product names.
1.
Function List
(1)
Built-in Power MOS FET Type
Table 1
Controll
system
PFM
PFM
PFM
PFM
PFM
Duty
ratio
[%]
50 / 75
50 / 75
75
75
50 / 75
Switching
frequency
[kHz]
100
100
100
100
100
Shutdown
function
Yes
−
−
−
−
V
DD
/ V
OUT
separate
type
−
−
−
−
Yes
Product Name
S-8351AxxMC
S-8351BxxMA
S-8351CxxMA
S-8351CxxUA
S-8351DxxMC
Package
SOT-23-5
SOT-23-3
SOT-23-3
SOT-89-3
SOT-23-5
Application
Applications requiring shutdown
function
Applications not requiring
shutdown function
Applications not requiring
shutdown function
Applications not requiring
shutdown function
Applications in which output
voltage is adjusted by external
resistor
(2)
External Power MOS FET Type
Table 2
Controll
System
PFM
PFM
PFM
PFM
PFM
Duty
Ratio
[%]
50 / 75
50 / 75
75
75
50 / 75
Switching
Frequency
[kHz]
100
100
100
100
100
Shutdown
Function
Yes
−
−
−
−
V
DD
/ V
OUT
Separate
Type
−
−
−
−
Yes
Product Name
S-8352AxxMC
S-8352BxxMA
S-8352CxxMA
S-8352CxxUA
S-8352DxxMC
Package
SOT-23-5
SOT-23-3
SOT-23-3
SOT-89-3
SOT-23-5
Application
Applications requiring shutdown
function
Applications not requiring
shutdown function
Applications not requiring
shutdown function
Applications not requiring
shutdown function
Applications in which output
voltage is adjusted by external
resistor
4
Seiko Instruments Inc.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0
_00
S-8351/8352 Series
2.
Package and Function List by Product Type
Table 3
Series Name
Type
A (Duty ratio 50% / 75% auto-switching type)
A = 100 kHz
B (Duty ratio 50% / 75% auto-switching type)
B = 100 kHz
C (Duty ratio 75% fixed type)
C = 100 kHz
D (Duty ratio 50% / 75% auto-switching type)
D = 100 kHz
Package Name Shutdown Function V
DD
/ V
OUT
Separate Type
(Abbreviation)
Yes / No
Yes / No
MC
MA
MA / UA
MC
Yes
No
No
No
No
No
No
Yes
S-8351 Series,
S-8352 Series
3.
Product Name
(1)
SOT-23-3
x
xx
MA - xxx
T2
G
Environmental code
G : Lead-free (for details, please contact our sales office)
IC direction in tape specifications
*1
Product name (abbreviation)
*2
Package name (abbreviation)
MA : SOT-23-3
Output voltage
15 to 65
(e.g. When the output voltage is 1.5 V, it is expressed as 15.)
Product type
A : With shutdown function,
B : 50% / 75% automatic duty ratio switching type,
C : 75% duty ratio fixed type,
D : V
DD
/ V
OUT
separate type,
Series name
1 : Built-in power MOS FET
2 : External power MOS FET
f
OSC
= 100 kHz
f
OSC
= 100 kHz
f
OSC
= 100 kHz
f
OSC
= 100 kHz
S-835 x
*1.
Refer to the tape specifications.
*2.
Refer to the
Table 4, 5
in the “5.
Product Name List”.
Seiko Instruments Inc.
5
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