S-8351/8352 Series
www.sii-ic.com
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING
REGULATOR / SWITCHING REGULATOR CONTROLLER
© Seiko Instruments Inc., 2002-2010 Rev.3.0_00
Seiko Instruments Inc. 1
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. (IOUT = 1 mA) guaranteed
• Low current consumption : During operation 23.2 μA (VOUT = 3.3 V, typ.)
During shutdown 0.5 μA (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)
• VDD / VOUT 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
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
2
Block Diagrams
1. S-8351 Series
(1) A Type (With shutdown function)
VSS
IC internal
power s u pp l y
VOUT
CONT
Protection
circuit
PFM
control
circuit
V
REF
OFF/ON
+
−
Figure 1
(2) B and C Types (Without shutdown function, VDD / VOUT non-separate type)
VSS
VOUT
CONT
Protecti on
circuit
PFM
control
circuit
V
REF
IC internal
power s upply
+
−
Figure 2
(3) D Type (VDD / VOUT separate type)
IC internal power supply
VSS
VOUTCONT
Protection
circuit
PFM
control
circuit
V
REF
+
−
VDD
Figure 3
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 3
2. S-8352 Series
(1) A Type (With shutdown function)
EXT
IC internal power supply
VSS
VOUT
PFM
control
circuit
V
REF
OFF/ON
+
−
Figure 4
(2) B and C Type (Without Shutdown function, VDD / VOUT non-separate type)
IC internal power supply
PFM
control
circuit
V
REF
EXT
VOUT
VSS
+
−
Figure 5
(3) D Type (VDD / VOUT separate type)
IC internal
power supply
EXT
VDD
VSS
VOUT
PFM
control
circuit
V
REF
+
−
Figure 6
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
4
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
Product Name Controll
system
Duty
ratio
[%]
Switching
frequency
[kHz]
Shutdown
function
VDD / VOUT
separate
type Package Application
S-8351AxxMC PFM 50 / 75 100 Yes − SOT-23-5
Applications requiring shutdown
function
S-8351BxxMA PFM 50 / 75 100 − − SOT-23-3
Applications not requiring
shutdown function
S-8351CxxMA PFM 75 100 − − SOT-23-3
Applications not requiring
shutdown function
S-8351CxxUA PFM 75 100 − − SOT-89-3
Applications not requiring
shutdown function
S-8351DxxMC PFM 50 / 75 100 − Yes SOT-23-5
Applications in which output
voltage is adjusted by external
resistor
(2) External Power MOS FET Type
Table 2
Product Name Controll
System
Duty
Ratio
[%]
Switching
Frequency
[kHz]
Shutdown
Function
VDD / VOUT
Separate
Type Package Application
S-8352AxxMC PFM 50 / 75 100 Yes − SOT-23-5
Applications requiring shutdown
function
S-8352BxxMA PFM 50 / 75 100 − − SOT-23-3
Applications not requiring
shutdown function
S-8352CxxMA PFM 75 100 − − SOT-23-3
Applications not requiring
shutdown function
S-8352CxxUA PFM 75 100 − − SOT-89-3
Applications not requiring
shutdown function
S-8352DxxMC PFM 50 / 75 100 − Yes SOT-23-5
Applications in which output
voltage is adjusted by external
resistor
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 5
2. Package and Function List by Product Type
Table 3
Series Name Type Package Name
(Abbreviation) Shutdown Function
Yes / No VDD / VOUT Separate Type
Yes / No
A (Duty ratio 50% / 75% auto-sw itching type)
A = 100 kHz MC Yes No
B (Duty ratio 50% / 75% auto-sw itching type)
B = 100 kHz MA No No
C (Duty ratio 75% fixed type)
C = 100 kHz MA / UA No No
S-8351 Series,
S-8352 Series
D (Duty ratio 50% / 75% auto-sw itching type)
D = 100 kHz MC No Yes
3. Product Name
(1) SOT-23-3
S-835 x x xx MA - xxx T2 G Environm ent al code
G : Lead-fre e (f or details, please co nt act our sales off i ce)
IC direction in tape specifications *1
Product name (abbreviation) *2
Package name (abbrev ia tio n)
MA : SOT-23-3
Output voltage
15 to 65
(e.g. When the ou tp ut volt age is 1.5 V, it is expr es sed as 15 .)
Product type
A : W it h sh ut do wn function, fOSC = 100 kHz
B : 50% / 75% auto m at ic dut y ratio switching type, fOSC = 100 kHz
C : 75% duty ratio fixed type, fOSC = 100 kHz
D : VDD / VOUT separate t ype, fOSC = 100 kHz
Series name
1 : Built-in power MOS FET
2 : External power MOS FET
*1. Refer to the tape specifications.
*2. Refer to the Table 4, 5 in the “5. Product Name List”.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
6
(2) SOT-23-5, SOT-89-3
S-835 x x xx xx - xxx T2 x Environm ental code
U : Lead-free (S n 100 %), halogen-fr ee
G : Lead-free (for details, please contact ou r sa les office)
IC direction in tape specifications *1
Product name (abbreviation) *2
Package name (abbrev ia tio n)
MC : SOT-23-5
UA : SOT-89-3
Output voltage
15 to 65
(e.g. When the ou tp ut volt age is 1.5 V , it is expr es sed as 15 .)
Product type
A : With shutdown function, fOSC = 100 kHz
B : 50% / 75% au to mat ic duty ratio switching type, fOSC = 100 kHz
C : 75% duty ratio fixed type, fOSC = 100 kHz
D : VDD / VOUT separate type, fOSC = 100 kHz
Series name
1 : Built-in power MOS FET
2 : External power MOS FET
*1. Refer to the tape specifications.
*2. Refer to the Table 4, 5 in the “5. Product Name List”.
4. Package
Drawing Code
Package Name Package Tape Reel
SOT-23-3 MP003-A-P-SD MP003-A-C-SD MP003-A-R-SD
SOT-23-5 MP005-A-P-SD MP005-A-C-SD MP005-A-R-SD
SOT-89-3 UP003-A-P-SD UP003-A-C-SD UP003-A-R-SD
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 7
5. Product Name List
(1) S-8351 Series
Table 4
Output
voltage S-8351AxxMC
Series S-8351BxxMA
Series S-8351CxxMA
Series S-8351CxxUA
Series S-8351DxxMC
Series
1.5 V
−
−
−
−
S-8351D15MC-J8AT2x
2.0 V
S-8351A20MC-J2FT2x
S-8351B20MA-J4FT2G
−
−
S-8351D20MC-J8FT2x
2.2 V
S-8351A22MC-J2HT2x
−
−
−
−
2.5 V
S-8351A25MC-J2KT2x
S-8351B25MA-J4KT2G
−
S-8351C25UA-J6KT2x
−
2.6 V
S-8351A26MC-J2LT2x
−
−
−
−
2.7 V
S-8351A27MC-J2MT2x
S-8351B27MA-J4MT2G
−
−
−
2.8 V
S-8351A28MC-J2NT2x
−
−
−
−
3.0 V
S-8351A30MC-J2PT2x
S-8351B30MA-J4PT2G
−
S-8351C30UA-J6PT2x
S-8351D30MC-J8PT2x
3.1 V
−
−
−
S-8351C31UA-J6QT2x
−
3.2 V
S-8351A32MC-J2RT2x
−
−
S-8351C32UA-J6RT2x
−
3.3 V
S-8351A33MC-J2ST2x
S-8351B33MA-J4ST2G S-8351C33MA-J6ST2G
S-8351C33UA-J6ST2x
−
3.5 V
S-8351A35MC-J2UT2x
−
−
S-8351C35UA-J6UT2x
−
4.0 V
S-8351A40MC-J2ZT2x
−
−
−
S-8351D40MC-J8ZT2x
4.5 V
S-8351A45MC-J3ET2x
S-8351B45MA-J5ET2G
−
−
−
4.6 V
−
S-8351B46MA-J5FT2G
−
−
−
4.7 V
S-8351A47MC-J3GT2x
−
−
−
−
5.0 V
S-8351A50MC-J3JT2x
S-8351B50MA-J5JT2G
−
S-8351C50UA-J7JT2x S-8351D50MC-J9JT2x
5.5 V
S-8351A55MC-J3OT2x
S-8351B55MA-J5OT2G
−
−
−
5.6 V
S-8351A56MC-J3PT2x
−
−
−
−
6.0 V
S-8351A60MC-J3TT2x
−
−
−
S-8351D60MC-J9TT2x
(2) S-8352 Series
Table 5
Output
voltage
S-8352AxxMC
Series S-8352BxxMA
Series S-8352CxxUA
Series S-8352DxxMC
Series
2.0 V
−
−
−
S-8352D20MC-K8FT2x
2.5 V
S-8352A25MC-K2KT2x
−
−
−
3.0 V
S-8352A30MC-K2PT2x S-8352B30MA-K4PT2G S-8352C30UA-K6PT2x S-8352D30MC-K8PT2x
3.1 V
−
−
S-8352C31UA-K6QT2x
−
3.2 V
S-8352A32MC-K2RT2x
−
S-8352C32UA-K6RT2x
−
3.3 V
S-8352A33MC-K2ST2x
−
S-8352C33UA-K6ST2x S-8352D33MC-K8ST2x
3.5 V
S-8352A35MC-K2UT2x
−
−
−
3.7 V
S-8352A37MC-K2WT2x
−
−
−
4.0 V
S-8352A40MC-K2ZT2x
−
−
−
4.6 V
S-8352A46MC-K3FT2x
−
−
−
4.7 V
S-8352A47MC-K3GT2x
−
−
−
5.0 V
S-8352A50MC-K3JT2x S-8352B50MA-K5JT2G S-8352C50UA-K7JT2x
−
5.4 V
S-8352A54MC-K3NT2x
−
−
−
5.6 V
−
−
S-8352C56UA-K7PT2x
−
Remark 1. Please contact the SII marketing department for products with an output voltage other than those specified above.
2. x: G or U
3. Please select products of environmental code = U for Sn 100%, halogen-free products.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
8
Pin Configurations
Table 6 S-8351 Series B an d C Types
(Without shutdown function, VDD / VOUT non-separate type)
Pin No. Symbol Pin Description
1 VOUT Output voltage pin and IC power supply pin
2 VSS GND pin
3 CONT External inductor connection pin (Open-drain output)
Table 7 S-8352 Series B an d C Types
(Without shutdown function, VDD / VOUT non-separate type)
Pin No. Symbol Pin Description
1 VOUT Output voltage pin and IC power supply pin
2 VSS GND pin
1
2 3
SOT-23-3
Top view
Figure 7
3 EXT
External transistor connection pin (CMOS output)
Table 8 S-8351 Series A Type
(With shutdown function, VDD / VOUT non-separate type)
Pin No. Symbol Pin Description
1 OFF/ON Shutdown pin
“H”: Normal operation (Step-up operating)
“L”: Step-up stopped (Entire circuit stopped)
2 VOUT Output voltage pin and IC power supply pin
3
NC*1 No connection
4 VSS GND pin
SOT-23-5
Top view
5 4
3 2 1
5 CONT External inductor connection pin (Open-drain output)
Figure 8 *1. The NC pin indicates electrically open.
Table 9 S-8352 Series A Type
(With shutdown function, VDD / VOUT non-separate type)
Pin No. Symbol Pin Description
1 OFF/ON Shutdown pin
“H”: Normal operation (Step-up operating)
“L”: Step-up stopped (Entire circuit stopped)
2 VOUT Output voltage pin and IC power supply pin
3
NC*1 No connection
4 VSS GND pin
5 EXT External transistor connection pin (CMOS output)
*1. The NC pin indicates electrically open.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 9
Table 10 S-8351 Series D T ype
(Without shutdown function, VDD / VOUT separate type)
Pin No. Symbol Pin Description
1 VOUT Output voltage pin
2 VDD IC power supply pin
3
NC*1 No connection
4 VSS GND pin
5 CONT External inductor connection pin (Open-drain output)
*1. The NC pin indicates electrically open.
Table 11 S-8352 Series D T ype
(Without shutdown function, VDD / VOUT separate type)
Pin No. Symbol Pin Description
1 VOUT Output voltage pin
2 VDD IC power supply pin
3
NC*1 No connection
4 VSS GND pin
5 EXT External transistor connection pin (CMOS output)
*1. The NC pin indicates electrically open.
Table 12 S-8351 Series C T ype
(Without shutdown function, VDD / VOUT non-separate type)
Pin No. Symbol Pin Description
1 VSS GND pin
2 VOUT Output voltage pin and IC power supply pin
3 CONT External inductor connection pin (Open-drain output)
SOT-89-3
Top view
3
2 1
Figure 9
Table 13 S-8352 Series C T ype
(Without shutdown function, VDD / VOUT non-separate type)
Pin No. Symbol Pin Description
1 VSS GND pin
2 VOUT Output voltage pin and IC power supply pin
3 EXT External transistor connection pin (CMOS output)
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
10
Absolute Maximum Ratings
Table 14 (Ta = 25°C unless otherwise specified)
Item Symbol Absolute maximum rating Unit
VOUT pin voltage VOUT V
SS − 0.3 to VSS + 12 V
OFF/ON pin voltage
*1 OFF/ON
V VSS − 0.3 to VSS + 12 V
VDD pin voltage *2 VDD V
SS − 0.3 to VSS + 12 V
CONT pin voltage VCONT V
SS − 0.3 to VSS + 12 V
D type VSS − 0.3 to VDD + 0.3 V
EXT pin voltage Others VEXT VSS − 0.3 to VOUT + 0.3 V
CONT pin current ICONT 300 mA
EXT pin current IEXT ±50 mA
150 (When not mounted on board) mW
SOT-23-3 430*3 mW
250 (When not mounted on board) mW
SOT-23-5 600*3 mW
500 (When not mounted on board) mW
Power dissipation
SOT-89-3
PD
1000*3 mW
Operating ambient temperature Topr − 40 to + 85 °C
Storage temperature Tstg − 40 to + 125 °C
*1. With shutdown function
*2. For VDD / VOUT separate type
*3. When mounted on board
[Mounted board]
(1) Board size : 114.3 mm × 76.2 mm × t1.6 mm
(2) Board name : JEDEC STANDARD51-7
Caution The absolute maximum ratings are rated values exceeding which the product could suffer physical
damage. These values must therefore not be exceeded under any conditions.
(1) When mounted on board (2) When not mounted on board
0 50 100
150
800
400
0
Power dissipation (P
D
) [mW]
Ambient temperature (Ta) [°C]
1000
600
200
1200
SOT-23-3
SOT-23-5
SOT-89-3
0 50 100
150
400
200
0
Power dissipation (P
D
) [mW]
Ambient temperature (Ta) [°C]
500
300
100
600
SOT-23-3
SOT-23-5
SOT-89-3
Figure 10 Po wer Dissip atio n of Packages
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 11
Electrical Characteristics
(1) S-8351 Series
Table 15 (1 / 2) (Ta = 25°C unless otherwise specified)
Item Symbol Condition Min. Typ. Max. Unit
Measurement
circuit
Output voltage V
OUT
−
V
OUT(S)
×
0.976 V
OUT(S)
V
OUT(S)
×
1.024 V 1
Input voltage V
IN
−
−
−
10 V 1
Operation start voltage V
ST1
I
OUT
= 1 mA
−
−
0.9 V 1
Oscillation start voltage V
ST2
No external parts, Voltage applied to V
OUT
,
CONT pin pulled up to V
OUT
with 300
Ω
resistor
−
−
0.8 V 2
S-8351x15 to 29
−
8.5
−
μ
A 1
S-8351x30 to 49
−
9.0
−
μ
A 1
Input current during no- load I
IN
I
OUT
= 0 mA S-8351x50 to 65
−
9.5
−
μ
A 1
S-8351x15 to 19
−
9.6 16.0
μ
A 2
S-8351x20 to 29
−
15.7 26.2
μ
A 2
S-8351x30 to 39
−
23.2 38.6
μ
A 2
S-8351x40 to 49
−
32.0 53.3
μ
A 2
S-8351x50 to 59
−
42.1 70.2
μ
A 2
Current consumption 1 I
SS1
V
OUT
= V
OUT(S)
×
0.95
S-8351x60 to 65
−
54.9 91.5
μ
A 2
S-8351x15 to 19
−
2.3 3.5
μ
A 2
S-8351x20 to 29
−
2.5 3.8
μ
A 2
S-8351x30 to 39
−
2.7 4.1
μ
A 2
S-8351x40 to 49
−
2.9 4.4
μ
A 2
S-8351x50 to 59
−
3.1 4.7
μ
A 2
Current consumption 2 I
SS2
V
OUT
= V
OUT(S)
+
0.5 V
S-8351x60 to 65
−
3.3 5.1
μ
A 2
Current consumption during
shutdown
(With shutdown function) I
SSS
OFF/ON
V
= 0 V
−
−
0.5
μ
A 2
S-8351x15 to 19 50.2 91.2
−
mA 2
S-8351x20 to 24 65.0 118.2
−
mA 2
S-8351x25 to 29 78.5 142.7
−
mA 2
S-8351x30 to 39 90.7 164.8
−
mA 2
S-8351x40 to 49 110.9 201.6
−
mA 2
S-8351x50 to 59 125.7 228.6
−
mA 2
Switching current I
SW
V
CONT
= 0.4 V
S-8351x60 to 65 135.2 245.8
−
mA 2
Switching transistor leakage
current I
SWQ
No external parts, V
CONT
= V
OUT
= 10 V,
OFF/ON
V
= 0 V
−
−
0.5
μ
A 2
CONT pin limit voltage V
CONTLMT
Apply to CONT pin, Confirm oscillation stop
−
0.9
−
V 2
Line regulation
Δ
V
OUT1
V
IN
= V
OUT(S)
×
0.4 to
×
0.6
−
30 60 mV 1
Load regulation
Δ
V
OUT2
I
OUT
= 10
μ
A to V
OUT(S)
/ 250
×
1.25
−
30 60 mV 1
Output voltage temperature
coefficient
OUT
OUT
VTaΔ
VΔ
•
Ta =
−
40
°
C to
+
85
°
C
−
±
50
−
ppm /
°
C 1
Oscillation frequency f
OSC
V
OUT
= V
OUT(S)
×
0.95,
Measured waveform at CONT pin 90 100 110 kHz 2
Duty ratio 1 Duty1 V
OUT
= V
OUT(S)
×
0.95,
Measured waveform at CONT pin 70 75 80 % 2
Duty ratio 2
(For A, B, D type) Duty2 Measured waveform at CONT pin at light load
−
50
−
% 1
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
12
Table 15 (2 / 2) (Ta = 25°C unless otherwise specified)
Item Symbol Condition Min. Typ. Max. Unit
Measurement
circuit
V
SH
V
OUT
= V
OUT(S)
×
0.95,
Measured oscillation at CONT pin 0.75
−
−
V 2
V
SL1
At V
OUT
≥
1.5 V
−
−
0.3 V 2
OFF/ON
pin input voltage
(With shutdown function) V
SL2
V
OUT
= V
OUT(S)
×
0.95,
Judged oscillation stop at
CONT pin At V
OUT
<
1.5 V
−
−
0.2 V 2
I
SH
OFF/ON
V
= 10 V
−
0.1
−
0.1
μ
A 2
OFF/ON
pin input current
(With shutdown function) I
SL
OFF/ON
V
= 0 V
−
0.1
−
0.1
μ
A 2
S-8351x30
−
86
−
% 1
Efficiency EFFI
−
S-8351x50
−
88
−
% 1
External parts
Coil: CDRH6D28-101 (100
μH) of Sumida Corporation
Diode: MA2Z748 (Shottky type) of Matsushita Electric Industrial Co. , Ltd.
Capacitor: F93 (16 V, 47 μF tantalum type) of Nichicon Corporation
VIN = VOUT(S) × 0.6 applied, IOUT = VOUT(S) / 250 Ω
With shutdown function : OFF/ON pin is connected to VOUT
For VDD / VOUT separate type : VDD pin is connected t o VOUT pin
Remark 1. V
OUT(S) specified above is the set output voltage value, and VOUT is the typical value of the actual output
voltage.
2. VDD / VOUT separate type
A step-up operation is performed from VDD = 0.8 V. However, 1.8 V≤VDD<10 V is recommended stabilizing
the output voltage and oscillation frequency. (VDD≥1.8 V must be applied for products with a set value of less
than 1.9 V.)
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 13
(2) S-8352 Series
Table 16 (1 / 2) (Ta = 25°C unless otherwise specified)
Item Symbol Condition Min. Typ. Max. Unit
Measurement
circuit
Output voltage V
OUT
−
V
OUT(S)
×
0.976 V
OUT(S)
V
OUT(S)
×
1.024 V 3
Input voltage V
IN
−
−
−
10 V 3
Operation start voltage V
ST1
I
OUT
= 1 mA
−
−
0.9 V 3
Oscillation start voltage V
ST2
No external parts, Voltage applied to V
OUT
−
−
0.8 V 4
S-8352x15 to 19
−
7.4 12.3
μ
A 4
S-8352x20 to 29
−
12.0 20.0
μ
A 4
S-8352x30 to 39
−
17.8 29.6
μ
A 4
S-8352x40 to 49
−
24.7 41.1
μ
A 4
S-8352x50 to 59
−
32.7 54.5
μ
A 4
Current consumption 1 I
SS1
V
OUT
= V
OUT(S)
×
0.95
S-8352x60 to 65
−
43.0 71.6
μ
A 4
S-8352x15 to 19
−
2.3 3.5
μ
A 4
S-8352x20 to 29
−
2.5 3.8
μ
A 4
S-8352x30 to 39
−
2.7 4.1
μ
A 4
S-8352x40 to 49
−
2.9 4.4
μ
A 4
S-8352x50 to 59
−
3.1 4.7
μ
A 4
Current consumption 2 I
SS2
V
OUT
= V
OUT(S)
+
0.5 V
S-8352x60 to 65
−
3.3 5.1
μ
A 4
Current consumption during
shutdown
(With shutdown function) I
SSS
OFF/ON
V
= 0 V
−
−
0.5
μ
A 4
S-8352x15 to 19
−
3.5
−
6.3
−
mA 4
S-8352x20 to 24
−
5.2
−
9.4
−
mA 4
S-8352x25 to 29
−
6.8
−
12.3
−
mA 4
S-8352x30 to 39
−
8.2
−
14.9
−
mA 4
S-8352x40 to 49
−
10.7
−
19.4
−
mA 4
S-8352x50 to 59
−
12.5
−
22.8
−
mA 4
I
EXTH
V
EXT
= V
OUT
−
0.4 V
S-8352x60 to 65
−
13.9
−
25.2
−
mA 4
S-8352x15 to 19 3.8 6.9
−
mA 4
S-8352x20 to 24 5.6 10.2
−
mA 4
S-8352x25 to 29 7.3 13.3
−
mA 4
S-8352x30 to 39 8.9 16.2
−
mA 4
S-8352x40 to 49 11.6 21.1
−
mA 4
S-8352x50 to 59 13.7 25.0
−
mA 4
EXT pin output current
I
EXTL
V
EXT
=
−
0.4 V
S-8352x60 to 65 15.3 27.8
−
mA 4
Line regulation
Δ
V
OUT1
V
IN
= V
OUT(S)
×
0.4 to
×
0.6
−
30 60 mV 3
Load regulation
Δ
V
OUT2
I
OUT
= 10
μ
A to V
OUT(S)
/ 100
×
1.25
−
30 60 mV 3
Output voltage temperature
coefficient
OUT
OUT
VTaΔ
VΔ
•
Ta =
−
40
°
C to
+
85
°
C
−
±
50
−
ppm /
°
C 3
Oscillation frequency f
OSC
V
OUT
= V
OUT(S)
×
0.95,
Measured waveform at EXT pin 90 100 110 kHz 4
Duty ratio 1 Duty1 V
OUT
= V
OUT(S)
×
0.95,
Measured waveform at EXT 70 75 80 % 4
Duty ratio 2
(For A, B, D type) Duty2 Measured waveform at EXT pin at light load
−
50
−
% 3
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
14
Table 16 (2 / 2) (Ta = 25°C unless otherwise specified)
Item Symbol Condition Min. Typ. Max. Unit
Measurement
circuit
V
SH
V
OUT
= V
OUT(S)
×
0.95,
Measured oscillation at EXT 0.75
−
−
V 4
V
SL1
At V
OUT
≥
1.5 V
−
−
0.3 V 4
OFF/ON
pin input voltage
(With shutdown function) V
SL2
V
OUT
= V
OUT(S)
×
0.95,
Judged oscillation stop at
EXT pin At V
OUT
<
1.5 V
−
−
0.2 V 4
I
SH
OFF/ON
V
= 10 V
−
0.1
−
0.1
μ
A 4
OFF/ON
pin input current
(With shutdown function) I
SL
OFF/ON
V
= 0 V
−
0.1
−
0.1
μ
A 4
S-8352x30
−
83
−
% 3
Efficiency EFFI
−
S-8352x50
−
85
−
% 3
External parts
Coil: CDRH6D28-101 (100
μH) from Sumida Corporation
Diode: MA2Z748 (Shottky type) from Matsushita Electric Industrial Co. , Ltd.
Capacitor: F93 (16 V, 47 μF tantalum type) from Nichicon Corporation
Transistor: CPH3210 from Sanyo Electric Co., Ltd.
Base resistor (Rb): 1 kΩ
Base capacitor (Cb): 2200 pH (ceramic type)
VIN = VOUT(S) × 0.6 applied, IOUT = VOUT(S) / 100 Ω
With shutdown function : OFF/ON pin is connected to VOUT
For VDD / VOUT separate type : VDD pin is connected to VOUT pin
Remark 1. V
OUT(S) specified above is the set output voltage value, and VOUT is the typical value of the actual output
voltage.
2. VDD / VOUT separate type
A step-up operation is performed from VDD = 0.8 V. However, 1.8 V≤VDD<10 V is recommended stabilizing
the output voltage and oscillation frequency. (VDD≥1.8 V must be applied for products with a set value of less
than 1.9 V.)
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Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 15
Measurement Circuits
1.
+
− V
VSS
CONT VOUT
VDD
*1
OFF/ON
*2
+
−
Figure 11
2.
300 Ω
Oscilloscope
A
VSS
VOUT
CONT
VDD
*1
OFF/ON
*2
+
−
Figure 12
3.
V
C
D
R
b
VSS
EXT
VOUT
VDD
*1
+
− +
−
OFF/ON
*2
Figure 13
4.
Oscilooscope
A
VSS
EXT
VOUT
VDD
*1
OFF/ON
*2
+
−
Figure 14
*1. For VDD / VOUT separate type
*2. With shutdown function
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
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16
Operation
1. Step-up DC-DC Converter
The S-8351/8352 Series is a DC-DC converter that uses a pulse frequency modulation method (PFM) and features
low current consumption. This series is an especially efficient DC-DC converter at an output current of 100 μA or
lower.
In conventional fixed-duty PFM DC-DC converters, although a low duty ratio allows a lower ripple voltage when the
current load is light, the efficiency is decreased when the output load current is large. Conversely, a high duty ratio
increases the output load current and efficiency, but increases the ripple voltage when the output load current is low.
In the A, B, and D types, the duty ratio is automatically switched 75% when the output load current is high to secure
the load drive capability and 50% when the output load current is low to control the load drive capability to decrease
pulse skipping. This suppresses a drop in the ripple frequency, enabling control of the increase in the ripple voltage.
The C type adopts a 75% fixed-duty PFM method. The ripple voltage increases more than that of the duty switching
type with the load is low, but the efficiency is better.
In the A, B, and D types, the duty ratio is not rapidly changed, but rather smoothly switched in the intermediate area
between 50% and 75%. Therefore, fluctuation of the ripple voltage caused by duty switching is minimized. Figures
15, 16 show the ripple voltage characteristics versus the output current.
S-8351A30MC Ta = 25°C S-8351A50MC Ta = 25°C
0
10
20
30
40
50
60
70
80
90
100
0
20
40
60
80 100
I
OUT
[mA]
V
r
p
-
p
[mV]
V
IN
= 1.5 V
V
IN
= 2 V
0
20
40
60
80
100
120
140
020 40 60 80
100
120
140
160 180
IOUT [mA]
Vr
p
-
p
[mV]
V
IN = 2 V
V
IN = 3 V
Figure 15 Output Current (IOUT) vs. Ripple Voltage (Vrp-p)
Characteristics Figure 16 Output Current (IOUT) vs. Ripple Voltage (Vrp-p)
Characteristics
These figures show that the ripple voltage decreases as the output load current (IOUT) changes from large to small.
The ripple voltage becomes particularly small when IOUT is in the coil current discontinuous region of 20 mA or less.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 17
2. OFFON/ Pin (Shutdown Pin) (A Type)
OFF/ON pin stops or starts step-up operation.
Setting the OFF/ON pin to the “L” level stops operation of all the internal circuits and reduces the current
consumption significantly.
DO NOT use the OFF/ON pin in a floating state because it has the structure shown in Figure 17 and is not pulled
up or pulled down internally. DO NOT apply a voltage of between 0.3 V and 0.75 V to the OFF/ON pin because
applying such a voltage increases the current consumption. If the shutdown pin is not used, connect it to the VOUT
pin.
The OFF/ON pin does not have hysteresis.
Table 17
OFF/ON pin CR oscillation circuit Output voltage
“H” Operation Fixed
“L” Stop
≅VIN*1
*1. Voltage obtained by subtracting the voltage drop due to the DC resistance of the inductor and the diode forward
voltage from VIN.
VSS
VOUT
OFF/ON
Figure 17 OFFON/ Pin Structure
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
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18
3. Operation
The following are the basic equations [(1) through (7)] of the step-up switching regulator. (Refer to Figure 18.)
+
−
+
−
OSC
CL
CONT
M1
VIN L Di
OFF/ON VOUT
Figure 18 Step-Up Switching Regulator Circuit for Basic Equation
Voltage at CONT pin at the moment M1 is turned ON (VA) *1 :
VA = VS *2 (1)
*1. Current flowing through L (IL) is zero.
*2. Non-saturated voltage of M1.
The change in IL over time :
LVV
L
V
dt
dI SINLL −
== (2)
Integration of equation (2) (IL) :
t
LVV
ISIN
L•
⎟
⎠
⎞
⎜
⎝
⎛−
= (3)
IL flows while M1 is ON (tON). The time of tON is determined by the oscillation frequency of OSC.
The peak current (IPK) after tON :
ON
SIN
PK t
LVV
I•
⎟
⎠
⎞
⎜
⎝
⎛−
= (4)
The energy stored in L is represented by 1/2 • L (IPK)2.
When M1 is turned OFF (tOFF), the energy stored in L is emitted through a diode to the output capacitor.
Then, the reverse voltage (V L) is generated :
VL = (VOUT + VD*1) − VIN (5)
*1. Diode forward voltage
The voltage at CONT pin rises only by VOUT+VD.
The change in the current (I L) flowing through the diode into VOUT during tOFF :
LVVV
L
V
dt
dI INDOUTLL −+
== (6)
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Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 19
Integration of the equation (6) is as follows :
t
LVVV
II INDOUT
PKL •
⎟
⎠
⎞
⎜
⎝
⎛−+
−= (7)
During tON, the energy is stored in L and is not transmitted to VOUT. When receiving the output current (IOUT) from
VOUT, the energy of the capacitor (CL) is consumed. As a result, the pin voltage of CL is reduced, and goes to the
lowest level after M1 is turned ON (tON). When M1 is turned OFF, the energy stored in L is transmitted through the
diode to CL, and the voltage of CL rises rapidly. VOUT is a time function, and therefore indicates the maximum value
(ripple voltage (VP−P) ) when the current flowing through into VOUT and load current (IOUT) match.
Next, the ripple voltage is determined as follows.
IOUT vs. t1 (time) from when M1 is turned OFF (after tON) to when VOUT reaches the maximum level :
1
INDOUT
PKOUT t
LVVV
II •
⎟
⎠
⎞
⎜
⎝
⎛−+
−= (8)
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−+
•−=∴
INDOUT
OUTPK1 VVV L
)II(t (9)
When M1 is turned OFF (tOFF), IL = 0 (when the energy of the inductor is completely transmitted). Based on equation (7) :
PK
OFF
INDOUT I
t
VVV L=
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−+ (10)
When substituting equation (10) for equation (9) :
OFF
PK
OUT
OFF1 t
I
I
tt •
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−= (11)
Electric charge ΔQ1 which is charged in CL during t1 :
2
1
INDOUT
1PK
1t
0
INDOUT
1t
0
PKL
1t
0
1t
2
1
LVVV
tItdt
LVVV
dtIdtIQ •
−+
−•=•
−+
−•==Δ ∫∫∫ (12)
When substituting equation (12) for equation (9) :
()
1
OUTPK
1OUTPKPK t
2II
tII
2
1
I1Q •
+
=•−−=Δ (13)
A rise in voltage (VP−P) due to ΔQ 1 :
1
OUTPK
LL
1
PP t
2II
C
1
C
QΔ
V•
⎟
⎠
⎞
⎜
⎝
⎛+
•==
− (14)
When taking into consideration IOUT to be consumed during t1 and the Equivalent Series Resistance (RESR) of CL :
L
1OUT
ESR
OUTPKOUTPK
LL
1
PP CtI
R
2II
1t
2II
C
1
C
Q
V•
−•
⎟
⎠
⎞
⎜
⎝
⎛+
+•
⎟
⎠
⎞
⎜
⎝
⎛+
•=
Δ
=
− (15)
When substituting equation (11) for equation (15) :
ESR
OUTPK
L
OFF
PK
2
OUTPK
PP R
2II
C
t
I2 )II(
V•
⎟
⎠
⎞
⎜
⎝
⎛+
+•
−
=
− (16)
Therefore to reduce the ripple voltage, it is important that the capacitor connected to the output pin has a large
capacity and a small RESR.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
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20
External Parts Selection
1. Inductor
To minimize the loss due to inductor direct current resistance, select an inductor with the smallest possible direct
current resistance (less than 1 Ω). Set the inductance value (L value) to around 22 μH to 1 mH.
To make the average value of the output voltage (VOUT) constant, it is necessary to supply the energy corresponding
to the output current (IOUT) from the inductor. The amount of charge required for IOUT is I OUT × (tON + tOFF). Because
the inductor can supply energy only during tOFF, the charge is obtained by integrating equation (7) in the “3.
Operation” in the “ Operation” with 0 → tOFF, namely, OFF
PK t
2
I•. Thus,
)tt(It
2
IOFFONOUTOFF
PK +×=• (17)
OUT
OFF
OFFON
PK I
ttt
2I •
+
•=∴ (18)
When the oscillation duty ratio of OSC is 75%, IPK = 8 • IOUT. Therefore, an IPK current which is eight times I OUT flows
into transistor (M1).
The S-8351 Series includes a switching current controller which monitors the current flowing into the CONT pin by
the voltage (CONT control voltage) and controls the current. This controller prevents destruction of the IC due to
excess current.
If an inductor with a large L value is selected, both IPK and IOUT decrease. Since the energy stored in the inductor is
equal to 2
PK )I( L
2
1•, the energy decreases because IPK decreases in steps of squares offsetting the increase of L
value. As a result, stepping up at a low voltage becomes difficult and the minimum operating input voltage becomes
high. However, the direct current resistance loss of L value and the M1 transistor decreases by the amount IPK
decreased, and the inductance efficiency improves.
On the other hand, if an inductor with a smaller L value is selected, both IPK and IOUT increase. Accordingly, the
minimum operating input voltage becomes low but the inductance efficiency deteriorates.
Caution An excessively large IPK may cause magnetic saturation for some core materials, leading to the
destruction of the IC. Use a core with material that satisfies Isat *1 > IPK
*1. Level of current that causes magnetic sat uration.
2. Diode
Use an external diode that meets the following requirements :
• Low forward voltage : VF < 0.3 V
• High switching speed : 500 ns max.
• Reverse voltage : VOUT + VF or more
• Current rate : IPK or more
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Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 21
3. Capacitor (CIN, CL)
A capacitor on the input side (CIN) improves the efficiency by reducing the power impedance and st abilizing the input
current. Select a CIN value according to the impedance of the power supply used.
A capacitor on the output side (CL) is used for smoothing the output voltage. For step-up types, the output voltage
flows intermittently to the load current, so step-up types need a larger capacitance than step-down types. Therefore,
select an appropriate capacitor in accordance with the ripple voltage, which increases in case of a higher output
voltage or a higher load current. The capacitor value should be 10 μF or more.
A capacitor at the output side (CL) is used for smoothing the ripple voltage. Select an appropriate capacitor with a
small equivalent series resistance (RESR) and a large capacitance. The capacitor value should be 10 μF or mpre. A
tantalum electrolytic capacitor and an organic semiconductor capacitor are especially recommended because of their
superior low-temperature and leakage current characteristics.
4. External Transistor (S-8352 Series)
For the S-8352 Series, connecting an external transistor increases the output current. An enhancement (N-channel)
MOS FET type or a bipolar (NPN) type can be used as the external transistor.
4. 1 Enhancement (N-channel) MOS FET Type
Figure 19 is a circuit example using a MOS FET transistor (N-channel).
V
OUT
EXT
VOUT
+
−
OFF/ON
*1
VSS
+
−
*1. For A type.
Figure 19 Circuit Example Using MOS FET (N-channel) Type
An N-channel power MOS FET should be used for the MOS FET. In particular, the EXT pin can drive a MOS
FET with a gate capacitance of around 1000 pF. Because the gate voltage and current of the external power
MOS FET are supplied from the stepped-up output voltage (VOUT), the MOS FET is driven more effectively.
A large current may flow during startup, depending on the MOS FET selection. The S-8352 Series does not
feature overcurrent protection for the external MOS FET, so perform sufficient evaluation using the actual devices.
Also recommend to use a MOS FET with an input capacitance of 700 pF or less.
Since the ON-resistance of the MOS FET might depend on the difference between the output voltage (VOUT) and
the threshold voltage of the MOS FET, and affect the output current as well as the efficiency, the threshold voltage
should be low. When the output voltage is as low as 2.0 V, like in the S-8352A20, the circuit operates only
when the MOS FET has a threshold voltage lower than the output voltage.
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S-8351/8352 Series Rev.3.0_00
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4. 2 Bipolar (NPN) Type
A circuit example using the CPH3210 (hFE = 200 to 560) from Sanyo Electric Co., Ltd. as a bipolar transistor
(NPN) is shown in Figure 24 to 26 in the “ Standard Circuits”. The hFE value and Rb value of the bipolar
transistor determine the driving capacity to increase the output current using a bipolar transistor. A peripheral
circuit example of the transistor is shown in Figure 20.
Nch
Pch
VOUT
*1
I
PK
EXT
C
b
2200 pF
R
b
1 kΩ
*1. VDD for D type.
Figure 20 External Transistor Peripheral Circuit
The recommended Rb value is around 1 kΩ. Actually, calculate the necessary base current (Ib) from the bipolar
transistor (hFE) using FE
PK
bh
I
I=, and select the smaller Rb value than EXTHb
OUT
bI 4.0
I7.0V
R−
−
= *1.
A small Rb value can increase the output current, but the efficiency decreases. Since a current may flow on the
pulse and the voltage may drop due to wiring resistance or other factors in the actual circuit, therefore the
optimum Rb value should be determined by experiment.
Connecting the speed-up capacitor (Cb) in parallel with the Rb resistance as shown in Figure 20, decreases
switching loss and improves the efficiency.
The Cb value is calculated according to 7.0fRπ21
Coscb
b•••
≤.
Select a Cb value after performing sufficient evaluation since the optimum Cb value differs depending upon the
characteristics of the bipolar transistor.
*1. For D type, EXTHb
DD
bI 4.0
I7.0V
R−
−
=.
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Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 23
5. VDD / VOUT Separate Type (For S-8351/8352 Series D Type)
The D type provides separate internal circuit power supply (VDD pin) and output voltage setting pin (VOUT pin) in the
IC, making it ideal for the following applications.
(1) Changing the output voltage value using an external resistor
(2) Setting a high output voltage value, such as +15 V
Cautions 1. This IC starts a step-up operation at VDD = 0.8 V, b ut set 1.8 ≤ VDD ≤ 10 V to stabilize the output
voltage and frequency of the oscillator. (Input a voltage of 1.8 V or more at the VDD pin for all
products w i th a setting less than 1.9 V.) An input voltage of 1.8 V or more at the VDD pin allows
connection of the VDD pin to either the input voltage VIN pin or output VOUT pin.
2. Choose external resistors RA and RB so as to not affect the output voltage, considering that th ere
is impedance betw een the VOUT pin and VSS pin in the IC chip. The internal resistance
betw een the VOUT pin and VSS pin is as follows :
(1) S-835xx18 : 2.1 MΩ to 14.8 MΩ
(2) S-835xx20 : 1.4 MΩ to 14.8 MΩ
(3) S-835xx30 : 1.4 MΩ to 14.2 MΩ
(4) S-835xx50 : 1.4 MΩ to 12.1 MΩ
3. Attach a capacitor (CC) in parallel to the RA resistance when an unstable event such as
oscillation of the output voltage occurs. Calculate CC using the following equation :
[]
kHz 20R2 1
CA
C•••
=π
F
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
24
Standard Circuits
1. S-8351 Series
(1) A type
CL
VREF
Protection
circuit
L CONT SD VOUT
VSS
VIN CIN PFM control
circuit
+
−
OFF/ON
+
−
+
−
Figure 21
(2) B and C types
V
REF
Protection
circuit
L CONT SD VOUT
VSS
V
IN
C
L
C
IN
PFM control
circuit
+
−
+
−
+
−
Figure 22
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 25
(3) D type
V
REF
Protection
circuit
L CONT SD
VSS
V
IN
C
L
C
IN
PFM control
circuit
IC internal
power
supply
VDD C
c
R
B
R
A
VOUT
+
−
+
−
+
−
Figure 23
Caution The above connection diagram will not guarantee successful operation. Perform through
evaluation using the actual application to set the constant.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
26
2. S-8352 Series
(1) A type
C
L
V
REF
SD VOUT
VSS
2200 pF
1 kΩ
C
IN
V
IN
EXT
PFM control
circuit
L
+
−
+
−
+
−
OFF/ON
Figure 24
(2) B and C types
C
L
V
REF
SD VOUT
VSS
PFM control
circuit
2200 pF
1 kΩ
C
IN
V
IN
EXT
L
+
−
+
−
+
−
Figure 25
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 27
(3) D type
C
L
V
REF
SD VDD
VSS
PFM control
circuit
2200 pF
1 kΩ
C
IN
V
IN
EXT
L C
c
R
B
R
A
VOUT
+
− +
−
+
−
IC internal
power
supply
Figure 26
Caution The above connection diagram and constants will not guarantee successful operation. Perform
through evaluation using the actual application to set the constant.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
28
Precautions
• Mount the external capacitors, the diode, and the coil as close as possible to the IC.
• Characteristics ripple voltage and spike noise occur in IC containing switching regulators. Moreover, rush current
flows at the time of a power supply injection. Because they largely depend on the coil and the capacitor and
impedance used, fully check them using an actually mounted model.
• Make sure that the dissipation of the switching transistor (especially at a high temperature) does not exceed the
allowable power dissipation of the package.
• The performance of this IC varies depending on the design of the PCB patterns, peripheral circuits and external parts.
Thoroughly test all settings with your device. Also, try to use the recommended external parts. If not, contact an SII
sales person.
• When the impedance of the power supply is high, the shutdown pin is switched from “L” to “H”, or VIN is connected to
the power supply, note that the power supply voltage drops temporarily because a rush current flows into the power
supply.
• Do not apply an electrostatic discharge to this IC that exceeds the performance ratings of the built-in electrostatic
protection IC.
• SII claims no responsibility for any and all disputes arising out of or in connection with any infringement of the products
including this IC upon patents owned by third party.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 29
Characteristics (Typical Data)
1. Input voltage (VIN) vs. Powe Supply Input Current at No Load (IIN)
Ta = 25°C
0
5
10
15
20
25
30
35
40
45
50
0 1 2 3 4 5
V
IN
[
V
]
I
IN
[μA]
S-8351A30MC
S-8351A50MC
2. Output Voltage (VOUT) vs. Current Consumption 1 (ISS1)
S-8351A S-8352A
0
20
40
60
80
I
SS1
[μA]
1 2 3 4 5 6 7
V
OUT
[V]
Ta = 25 °C
0
20
40
60
80
I
SS1
[μA]
V
OUT
[V]
1234 5 6 7
Ta = 25 °C
3. Temperature (Ta) vs. Current Consumption 1 (ISS1)
0
20
30
40
50
I
SS1
[μA]
10
−50 −25 0 25 50 75 100
Ta
[
°C
]
S-8351A30MC
S-8351A50MC
0
20
30
40
50
I
SS1
[μA]
10
−
50
−
25 0 25 50 75 100
Ta
[
°C
]
S-8352A30MC
S-8352A50MC
4. Output Voltage (V
OUT
) vs. Current Consumption 2 (I
SS2
) 5. Temperature (Ta) vs. Current Consumption 2 (I
SS2
)
Ta = 25°C
0
1
2
3
4
I
SS2
[μA]
V
OUT
[
V
]
1 2 3 4 5 6 7
5
0
2
3
4
5
I
SS1
[μA]
1
−
50
−
25 0 25 50 75 100
Ta
[
°C
]
S-8351A30MC
S-8351A50MC
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
30
6. Temperature (Ta) vs. Oscillation Frequency (fOSC)
100
110
120
130
140
−50 −25 0 25 50 75 100
Ta
[
°C
]
fOSC [kHz]
80
90
S-8351A30MC
S-8351A50MC
7. Temperature (Ta) vs. Duty Ratio 1 (Duty1) 8. Temperature (Ta) vs. Duty Ratio 2 (Duty2)
Duty1 [%]
70
72
74
76
78
80
−50 −25 0 25 50 75 100
Ta [°C]
S-8351A30MC
S-8351A50MC
Duty2 [%]
45
47
49
51
53
55
−
50
−
25 0 25 50 75 100
Ta
[
°C
]
S-8351A30MC
S-8351A50MC
9. Output Voltage (V
OUT
) vs. Switching Current (I
SW
) 10. Temperature (Ta) vs. Switching Current (I
SW
)
Ta = 25°C
0
50
0 1 2 3 4 5 6 7
V
OUT
[
V
]
I
SW
[mA]
100
150
200
250
300
400
I
SW
[mA]
−
50
−
25 0 25 50 75 100
Ta
[
°C
]
0
50
200
250
300
350
150
100 S-8351A30MC
S-8351A50MC
11. Output Voltage (V
OUT
) vs. EXT Pin Output Current “H” (I
EXTH
)
12. Temperature (Ta) vs. EXT Pin Output Current “H” (I
EXTH
)
Ta = 25°C
10
15
20
25
30
35
IEXTH [mA]
0 1 2 3 4 5 6 7
VOUT [V]
0
5
0
10
20
30
40
I
EXTH
[mA]
−
50
−
25 0 25 50 75 100
Ta [°C]
S-8352A30MC
S-8352A50MC
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 31
13. Output Voltage (V
OUT
) vs. EXT Pin Output Current “L” (I
EXTL
)
14. Temperature (Ta) vs. EXT Pin Output Current “L” (I
EXTL
)
Ta = 25°C
10
15
20
25
30
35
I
EXTL
[mA]
0 1 2 3 4 5 6 7
V
OUT
[V]
0
5
0
10
20
30
40
I
EXT L
[mA]
−
50
−
25 0 25 50 75 100
Ta [°C]
S-8352A30MC
S-8352A50MC
15. Temperature (Ta) vs. Operation Start Voltage (V
ST1
) 16. Temperature (Ta) vs. Retention Voltage (V
HLD
)
0.6
0.7
0.8
0.9
1.0
V
ST1
[V]
−50 −25 0 25 50 75 100
Ta
[
°C
]
S-8351A30MC
S-8351A50MC
0.4
0.5
0.6
0.7
0.8
V
HLD
[V]
−
50
−
25 0 25 50 75 100
Ta [°C]
0.2
0.3
S-8351A30MC
S-8351A50MC
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
32
17. Transient Response Characteristics
The conditions for external parts are the same as those specified in the electrical characteristics.
(1) Power-on (Ta = 25°C, RL = 250 Ω)
S-8351A30MC VIN = 0 → 1.8 V S-8351A50MC VIN = 0 → 3 V
t [0.2 ms / div]
Input voltage
[
0.5 V / div
]
Output voltage
[0.5 V / div]
0 V
0 V
1.8 V
3 V
t [0.2 ms / div]
Input voltage
[1 V
/
div]
Output voltage
[1 V
/
div]
0 V
0 V
3 V
5 V
S-8352A30MC VIN = 0 → 1.8 V S-8352A50MC VIN = 0 → 3 V
t [0.2 ms / div]
Input voltage
[0.5 V / div]
Output voltage
[0.5 V / div]
0 V
0 V
1.8 V
3 V
t [0.2 ms / div]
Input voltage
[1 V
/
div]
Output voltage
[1 V
/
div]
0 V
0 V
3 V
5 V
(2) Power Supply Voltage Fluctuation (Ta = 25°C, RL = 250 Ω)
S-8351A30MC VIN = 1.2 → 1.8 V S-8351A30MC VIN = 1.8 → 1.2 V
t [0.1 ms / div]
Input voltage
[0.5 V /div]
Output voltage
[
0.1 V / div
]
1.2 V 1.8 V
3 V
t [0.1 ms / div]
Input voltage
[0.5 V
/
div]
Output voltage
[0.1 V
/
div]
1.8 V 1.2 V
3 V
S-8351A50MC VIN = 2 → 3 V S-8351A50MC VIN = 3 → 2 V
t [0.1 ms / div]
Input voltage
[0.5 V / div]
Output voltage
[
0.1 V / div
]
2 V
3 V
5 V
t [0.1 ms / div]
Input voltage
[0.5 V
/
div]
Output voltage
[0.1 V
/
div]
3 V
2 V
5 V
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 33
S-8352A30MC VIN = 1.2 → 1.8 V S-8352A30MC VIN = 1.8 → 1.2 V
t [0.1 ms / div]
Output voltage
[0.1 V / div]
1.2 V 1.8 V
3 V
Input voltage
[0.5 V /div]
t [0.1 ms / div]
Input voltage
[0.5 V
/
div]
Output voltage
[0.1 V
/
div]
1.8 V 1.2 V
3 V
S-8352A50MC VIN = 2 → 3 V S-8352A50MC VIN = 3 → 2 V
t [0.1 ms / div]
Output voltage
[
0.1 V / div
]
2 V
3 V
5 V
Input voltage
[
0.5 V /div
]
t [0.1 ms / div]
Input voltage
[0.5 V
/
div]
Output voltage
[0.1 V
/
div]
3 V
2 V
5 V
(3) Load Current Fluctuation (Ta = 25°C)
S-8351A30MC
VIN = 1.8 V, IOUT = 10 μA → 12 mA S-8351A30MC
VIN = 1.8 V, IOUT = 12 mA → 10 μA
t [0.1 ms / div]
Output current
Output voltage
[0.1 V / div] 3 V
I
OUT
= 12 mA
t [0.1 ms / div]
Output current
Output voltage
[0.1 V
/
div] 3 V
I
OUT
= 10
μ
A
S-8351A50MC
VIN = 3 V, IOUT = 10 μA → 20 mA S-8351A50MC
VIN = 3 V, IOUT = 20 mA → 10 μA
t [0.1 ms / div]
5 V
Output current
Output voltage
[0.1 V / div]
IOUT = 20 mA
t [0.1 ms / div]
5 V
Output current
Output voltage
[0.1 V
/
div]
IOUT = 10
μ
A
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
34
S-8352A30MC
VIN = 1.8 V, IOUT = 10 μA → 12 mA S-8352A30MC
VIN = 1.8 V, IOUT = 12 mA → 10 μA
t [0.1 ms / div]
Output current
Output voltage
[0.1 V / div] 3 V
IOUT = 12 mA
t [0.1 ms / div]
Output current
Output voltage
[0.1 V
/
div] 3 V
IOUT = 10
μ
A
S-8352A50MC
VIN = 3 V, IOUT = 10 μA → 20 mA S-8352A50MC
VIN = 3 V, IOUT = 20 mA → 10 μA
t [0.1 ms / div]
5 V
Output current
Output voltage
[0.1 V / div]
I
OUT
= 20 mA
t [0.1 ms / div]
5 V
Output current
Output voltage
[0.1 V / div]
I
OUT
= 10
μ
A
(4) OFFON/ Pin Response (Ta = 25°C, RL = 250 Ω)
S-8351A30MC VIN = 1.8 V S-8351A50MC VIN = 3 V
t [0.1 ms / div]
Output voltage
[0.3 V / div]
3 V
OFF
OFF/ON
voltage ON
t [0.1 ms / div]
Output voltage
[0.5 V / div]
5 V
OFF
OFF/ON
voltage ON
S-8352A30MC VIN = 1.8 V S-8352A50MC VIN = 3 V
t
[
0.1 ms / div
]
3 V
Output voltage
[0.3 V / div]
OFF ON
OFF/ON
voltage
t
[
0.1 ms / div
]
5 V
Output voltage
[0.5 V / div]
OFF ON
OFF/ON
voltage
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 35
Reference Data
Use this reference data to choose the external parts. This reference data makes it possible to choose the
recommended external part based on the application and characteristics data.
1. External Parts for Reference Data
Table 18
Condition Product Name Output
Voltage
V
Power
MOS FET Coil
1 S-8351A30MC 3.0 Built-in CDRH6D28-470
2 S-8351A30MC 3.0 Built-in CDRH6D28-101
3 S-8351A30MC 3.0 Built-in CXLP120-101
4 S-8351A50MC 5.0 Built-in CDRH6D28-101
5 S-8351A50MC 5.0 Built-in CDRH125-221
6 S-8351A50MC 5.0 Built-in CXLP120-470
7 S-8352A30MC 3.0 External CDRH6D28-220
8 S-8352A30MC 3.0 External CDRH6D28-101
9 S-8352A30MC 3.0 External CXLP120-470
10 S-8352A50MC 5.0 External CDRH6D28-220
11 S-8352A50MC 5.0 External CDRH6D28-101
12 S-8352A50MC 5.0 External CXLP120-101
The properties of the external parts are shown below.
Table 19 Evaluation coil
Part Product Name Manufacturer Characteristics
CDRH6D28-220 Sumida Corporation 22 μH, DCR *1 = 0.128 Ω, IMAX *2 = 1200 mA
CDRH6D28-470 Sumida Corporation 47 μH, DCR *1 = 0.238 Ω, IMAX *2 = 800 mA
CDRH6D28-101 Sumida Corporation 100 μH, DCR *1 = 0.535 Ω, IMAX *2 = 540 mA
CDRH125-221 Sumida Corporation 220 μH, DCR *1 = 0.4 Ω, IMAX *2 = 800 mA
CXLP120-470 Sumitomo Special Metals Co., Ltd 47 μH, DCR *1 = 0.95 Ω, IMAX *2 = 450 mA
Coil
CXLP120-101 Sumitomo Special Metals Co., Ltd 100 μH, DCR *1 = 2.5 Ω, IMAX *2 = 200 mA
*1. Direct current resistance
*2. Maximum allowable current
Table 20 Prop erties o f External Parts
Part Product Name Manufacturer Characteristics
Diode MA2Z748
Matsushita Electronic Components
Co., Ltd. VF*1 = 0.4V, IF*2 = 0.3A
(Shottky type)
Capacitor
(Output
capacitance) F93 Nichicon Corporation 16V, 47μF
(Tantalum type)
Transistor
(NPN) CPH3210 Sanyo Electric Co.,Ltd. VCBO*3 = 40V, VCEO*4 = 30V
hFE*5 = 200 min. (VCE = 2V, IC = 500mA)
fT*6 = 290 MHz typ. (VCE = 10V, IC = 500mA)
*1. Forward voltage, *2. Forward current, *3. Collector-to-base voltage, *4. Collector-to-emitter voltage, *5. DC
current gain, *6. Gain-bandwidth product
Caution The above values shown in the characteristics column of Table 19 and 20 are based on the
materials provided by each manufacture. However, consider the characteristics of the original
materials when using the above products.
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
36
2. Step-up Characteristics (Ta = 25°C)
The data of the step- up characteristics ((a) Input voltage (VIN) vs. Output voltage (VOUT) characteristics (Input voltage
stepped up), (b) Input voltage (VIN) vs. Output voltage (VOUT) characteristics (Input voltage stepped down), (c) Output
current (IOUT) vs. Output voltage (VOUT) characteristics, (d) Output current (IOUT) vs. Efficiency (η) characteristics
under conditions of 1 to 12 in Table 18 is shown below.
Condition 1 S-8351A30MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising) (b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
2.8
2.9
3.0
3.1
3.2
2.6
2.7
VOUT [V]
VIN
[
V
]
2 3 41 0
I
OUT
=
0.1 m A
I
OUT
=
1 mA
I
OUT
=
10 m A
I
OUT
=
20 m A
I
OUT
=
50 m A
I
OUT
=
100 mA
2.8
2.9
3.0
3.1
V
IN
[
V
]
V
OUT
[V]
2 3 410
3.2
2.6
2.7
I
OUT
=
0.1 m A
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
20 m A
I
OUT
=
50 m A
I
OUT
=
100 mA
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
) (d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
2.8
2.9
3.0
3.1
I
OUT
[mA]
V
OUT
[V]
100 150 200 50 0
3.2
2.6
2.7
250
V
IN
=
1.0 V , V
IN
=
2.0 V
V
IN
=
1.5 V , V
IN
=
2.5 V
V
IN
=
1.8 V
50
60
70
η [%]
I
OUT
[
mA
]
1 10 100 10000.10.01
V
IN
=
1.0 V
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
80
90
Condition 2 S-8351A30MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising) (b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
2.8
2.9
3.0
3.1
V
IN
[
V
]
V
OUT
[V]
2 3 41 0
3.2
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
20 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
2.8
2.9
3.0
3.1
V
IN
[
V
]
V
OUT
[V]
2 3 410
3.2
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
20 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
3.0
2.8
2.9
3.1
I
OUT
[
mA
]
V
OUT
[V]
100 150 200 50 0
3.2
2.6
2.7
250
V
IN
=
1.0 V, V
IN
=
2.0 V
V
IN
=
1.5 V, V
IN
=
2.5 V
V
IN
=
1.8 V
50
60
70
80
η [%]
IOUT
[
mA
]
1 10 100 10000.10.01
90
V
IN
=
1.0 V
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 37
Condition 3 S-8351A30MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
2.8
2.9
3.0
3.1
V
IN
[
V
]
V
OUT
[V]
2 3 41 0
3.2
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
20 mA
I
OUT
=
50 mA
2.8
2.9
3.0
3.1
V
IN
[
V
]
V
OUT
[V]
2 3 410
3.2
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
20 mA
I
OUT
=
50 mA
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
3.0
2.8
2.9
3.1
I
OUT
[
mA
]
V
OUT
[V]
100 150 200 50 0
3.2
2.6
2.7
250
V
IN
=
1.0 V
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
50
60
70
η [%]
I
OUT
[mA]
1 10 100 10000.10.01
V
IN
=
1.0 V
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
80
90
Condition 4 S-8351A50MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
4.8
4.9
5.0
5.1
V
IN
[
V
]
V
OUT
[V]
2 3 5 1 0
5.2
4.6
4.7
4 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
4.8
4.9
5.0
5.1
V
IN
[V]
V
OUT
[V]
5.2
4.6
4.7
23 5 104 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
5.1
5.0
4.8
4.9
I
OUT
[mA]
V
OUT
[V]
100 150 200 50 0
5.2
4.6
4.7
250
V
IN
=
1.5 V
V
IN
=
2.0 V
V
IN
=
3.0 V
60
70
80
90
η
[%]
I
OUT
[
mA
]
1 10 100 10000.10.01
100
V
IN
=
1.0 V
V
IN
=
1.5 V
V
IN
=
2.0 V
V
IN
=
3.0 V
V
IN
=
4.0 V
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
38
Condition 5 S-8351A50MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
4.8
4.9
5.0
5.1
V
IN
[V]
V
OUT
[V]
2 3 5
1
0
5.2
4.6
4.7
4 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
4.8
4.9
5.0
5.1
V
IN
[V]
V
OUT
[V]
4.6
4.7
23 5 104 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
5.2
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
4.8
4.9
5.0
5.1
I
OUT
[mA]
V
OUT
[V]
100 150 200 50 0
5.2
4.6
4.7
250
V
IN
=
1.5 V
V
IN
=
2.0 V
V
IN
=
3.0 V
60
70
80
90
η
[%]
I
OUT
[mA]
1 10 100 10000.10.01
100
V
IN
=
1.0 V
V
IN
=
1.5 V
V
IN
=
2.0 V
V
IN
=
3.0 V
V
IN
=
4.0 V
Condition 6 S-8351A50MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
4.8
4.9
5.0
5.1
V
IN
[
V
]
V
OUT
[V]
2 3 5 1 0
4.6
4.7
4 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
5.2
4.8
4.9
5.0
5.1
VIN [V]
VOUT [V]
4.6
4.7
23 5 104 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
5.2
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
4.8
4.9
5.0
5.1
I
OUT
[mA]
V
OUT
[V]
5.2
4.6
4.7
100 150 200 50 0 250
V
IN
=
1.5 V
V
IN
=
2.0 V
V
IN
=
3.0 V
50
60
70
80
η
[%]
IOUT
[
mA
]
1 10 100
1000
0.10.01
90
V
IN
=
1.0 V
V
IN
=
1.5 V
V
IN
=
2.0 V
V
IN
=
3.0 V
V
IN
=
4.0 V
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 39
Condition 7 S-8352A30MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
2.8
2.9
3.0
3.1
VIN [V]
VOUT [V]
2 3 41 0
3.2
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
2.8
2.9
3.0
3.1
V
IN
[V]
V
OUT
[V]
2 3 410
3.2
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
0 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
2.8
2.9
3.0
3.1
I
OUT
[mA]
V
OUT
[V]
100 150 200 50 0
3.2
2.6
2.7
250 300 350
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
50
60
70
80
η
[%]
I
OUT
[
mA
]
1 10 100 10000.10.01
90
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
Condition 8 S-8352A30MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
2.8
2.9
3.0
3.1
V
IN
[V]
V
OUT
[V]
2 3 41 0
3.2
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
2.8
2.9
3.0
3.1
V
IN
[
V
]
V
OUT
[V]
2 3 410
3.2
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
2.8
2.9
3.0
3.1
I
OUT
[
mA
]
V
OUT
[V]
3.2
2.6
2.7
100 150 200 50 0 250 300 350
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
50
60
70
80
η
[%]
IOUT
[
mA
]
1 10 100 10000.10.01
90
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
S-8351/8352 Series Rev.3.0_00
Seiko Instruments Inc.
40
Condition 9 S-8352A30MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
2.8
2.9
3.0
3.1
V
IN
[V]
V
OUT
[V]
2 3 41 0
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
3.2
2.8
2.9
3.0
3.1
V
IN
[
V
]
V
OUT
[V]
2 3 410
3.2
2.6
2.7
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
I
OU
T
[
mA
]
V
OUT
[V]
100 150 200 50
2.8
2.9
3.0
3.1
3.2
2.6
2.7
0 250 300 350
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
50
60
70
80
η
[%]
IOUT
[
mA
]
1 10 100 10000.10.01
V
IN
=
1.5 V
V
IN
=
1.8 V
V
IN
=
2.0 V
V
IN
=
2.5 V
90
Condition 10 S-8352A50MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
4.8
4.9
5.0
5.1
V
IN
[
V
]
V
OUT
[V]
2 3 5 1 0
5.2
4.6
4.7
4 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
4.8
4.9
5.0
5.1
V
IN
[V]
V
OUT
[V]
5.2
4.6
4.7
23 5 104 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
4.8
4.9
5.0
5.1
I
OUT
[mA]
V
OUT
[V]
100 200 300 50 0
5.2
4.6
4.7
400150 250 350 450
V
IN
=
1.5 V
V
IN
=
2.0 V
V
IN
=
3.0 V
V
IN
=
4.0 V
50
60
70
80
η [%]
I
OUT
[mA]
1 10 100 10000.10.01
90
V
IN
=
2.0 V
V
IN
=
3.0 V
V
IN
=
4.0 V
STEP-UP, BUILT-IN / EXTERNAL FET PFM CONTROL SWITCHING REGULATOR / SWITCHING REGULATOR CONTROLLER
Rev.3.0_00 S-8351/8352 Series
Seiko Instruments Inc. 41
Condition 11 S-8352A50MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
4.8
4.9
5.0
5.1
V
IN
[V]
V
OUT
[V]
2 3 5 1 0
4.6
4.7
4 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
5.2
V
IN
[
V
]
V
OUT
[V]
23 5 1
4.8
4.9
5.0
5.1
5.2
4.6
4.7
04 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
I
OUT
=
150 mA
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
4.8
4.9
5.0
5.1
I
OUT
[mA]
V
OUT
[V]
4.6
4.7
100 200 300 50 0 400150 250 350 450
V
IN
=
1.5 V
V
IN
=
2.0 V
V
IN
=
3.0 V
V
IN
=
4.0 V
5.2
50
60
70
90
80
η
[%]
I
OUT
[mA]
1 10 100 10000.10.01
V
IN
=
2.0 V
V
IN
=
3.0 V
V
IN
=
4.0 V
Condition 12 S-8352A50MC
(a) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage raising)
(b) Input voltage (V
IN
) vs. Output voltage (V
OUT
)
(Input voltage falling)
4.8
4.9
5.0
5.1
V
IN
[V]
V
OUT
[V]
2 3 5 1 0
5.2
4.6
4.7
4 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
4.8
4.9
5.0
5.2
V
IN
[
V
]
V
OUT
[V]
4.6
4.7
23 5 104 6
I
OUT
=
0.1 mA
I
OUT
=
1 mA
I
OUT
=
10 mA
I
OUT
=
50 mA
I
OUT
=
100 mA
5.1
(c) Output current (I
OUT
) vs.Output voltage (V
OUT
)
(d) Output cu rrent (I
OUT
) vs. Efficiency (
η
)
4.8
4.9
5.0
5.1
I
OUT
[
mA
]
V
OUT
[V]
5.2
4.6
4.7
100 200 300 50 0 400150 250 350 450
V
IN
=
2.0 V
V
IN
=
3.0 V
V
IN
=
4.0 V
50
60
70
80
η
[%]
I
OUT
[mA]
1 10 100 10000.10.01
90
V
IN
=
3.0 V
V
IN
=
4.0 V
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
2.9±0.2
0.95±0.1
1.9±0.2
+0.1
-0.05
0.16
0.4±0.1
1
23
No. MP003-A-P-SD-1.1
MP003-A-P-SD-1.1
SOT233-A-PKG Dimensions
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
1.6±0.1
0.25±0.05
4.0±0.1
2.0±0.1
4.0±0.1
1.5 +0.1
-0.05
1.1±0.1
2.85±0.2
No. MP003-A-C-SD-1.1
MP003-A-C-SD-1.1
SOT233-A-Carrier Tape
Feed direction
1
23
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
(60°)
(60°)
ø13±0.2
12.5max.
9.0±0.3
QTY. 3,000
No. MP003-A-R-SD-1.1
MP003-A-R-SD-1.1
SOT233-A-Reel
Enlarged drawing in the central part
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
2.9±0.2
1.9±0.2
0.95±0.1
0.4±0.1
0.16 +0.1
-0.06
123
4
5
No. MP005-A-P-SD-1.2
MP005-A-P-SD-1.2
SOT235-A-PKG Dimensions
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
ø1.5 +0.1
-0 2.0±0.05
ø1.0 +0.2
-0 4.0±0.1
1.4±0.2
0.25±0.1
3.2±0.2
123
45
No. MP005-A-C-SD-2.1
MP005-A-C-SD-2.1
SOT235-A-Carrier Tape
Feed direction
4.0±0.1(10 pitches:40.0±0.2)
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
12.5max.
9.0±0.3
ø13±0.2
(60°) (60°)
QTY. 3,000
No. MP005-A-R-SD-1.1
MP005-A-R-SD-1.1
SOT235-A-Reel
Enlarged drawing in the central part
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
0.4±0.05
1.5±0.1
4.5±0.1
1.6±0.2
1.5±0.1 1.5±0.1
0.45±0.1
0.4±0.1
0.4±0.1
45°
312
No. UP003-A-P-SD-1.1
UP003-A-P-SD-1.1
SOT893-A-PKG Dimensions
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
2.0±0.1
0.3±0.05
8.0±0.1
ø1.5+0.1
-0
2.0±0.05
ø1.5+0.1
-0
4.75±0.1
5° max.
No. UP003-A-C-SD-1.1
UP003-A-C-SD-1.1
SOT893-A-Carrier Tape
Feed direction
4.0±0.1(10 pitches : 40.0±0.2)
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
13.0±0.3
16.5max.
(60°)
(60°)
QTY. 1,000
No. UP003-A-R-SD-1.1
UP003-A-R-SD-1.1
SOT893-A-Reel
Enlarged drawing in the central part
www.sii-ic.com
• The information described herein is subject to change without notice.
• Seiko Instruments Inc. is not responsible for any problems caused by circuits or diagrams described herein
whose related industrial properties, patents, or other rights belong to third parties. The application circuit
examples explain typical applications of the products, and do not guarantee the success of any specific
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• Although Seiko Instruments Inc. exerts the greatest possible effort to ensure high quality and reliability, the
failure or malfunction of semiconductor products may occur. The user of these products should therefore
give thorough consideration to safety design, including redundancy, fire-prevention measures, and
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