Rev.1.4_00
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE
BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series
Seiko Instruments Inc. 1
The S-8353/8354 Series is a CMOS step-up switching regulator which
mainly consists of a reference voltage source, an oscillation circuit, a
power MOS FET, an error amplifier, a phase compensation circuit, a PWM
control circuit (S-8353 Series) and a PWM / PFM switching control circuit
(S-8354 Series).
The S-8353/8354 Series can configure the step-up switching regulator with
an external coil, capacitor, and diode. In addition to the above features,
the small package and low current consumption make the S-8353/8354
Series ideal for portable equipment applications requiring high efficiency.
The S-8353 Series realizes low ripple, high efficiency, and excellent
transient characteristics due to its PWM control circuit whose duty ratio
can be varied linearly from 0 to 83% (from 0 to 78% for 250 kHz models),
an excellently designed error amplifier, and phase compensation circuits.
The S-8354 Series features a PWM / PFM switching controller that can
switch the operation to a PFM controller with a duty ratio is 15% under a
light load to prevent a decline in the efficiency due to the IC operating
current.
Features
• Low voltage operation: Startup at 0.9 V min. (IOUT = 1 mA) guaranteed
• Low current consumption : During operation 18.7 µA (3.3 V, 50 kHz, typ.)
During shutdown: 0.5 µA (max.)
• Duty ratio : Built-in PWM / PFM switching control circuit (S-8354 Series)
15 % to 83 % (30 kHz and 50 kHz models)
15 % to 78 % (250 kHz models)
• External parts : Coil, capacitor, and diode
• Output voltage : Selectable in 0.1 V steps between 1.5 and 6.5 V (for VDD / VOUT separate types)
Selectable in 0.1 V steps between 2.0 and 6.5 V (for other than VDD / VOUT separate types)
• Output voltage accuracy : ±2.4%
• Oscillation frequency : 30 kHz, 50 kHz, and 250 kHz selectable
• Soft start function : 6 ms (50 kHz, typ.)
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, VCRs, and communication devices
• Power supplies for microcomputers
Packages
Drawing Code
Package Name Package Tape Reel
SOT-23-3 MP003-A MP003-A MP003-A
SOT-23-5 MP005-A MP005-A MP005-A
SOT-89-3 UP003-A UP003-A UP003-A
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
2
Block Diagrams
(1) A, C and H Types (Without Shutdown Function)
CONT VOUT
Oscillation circuit
PWMcontrol circuit
or PWM / PFM
swiching control
circuit
VSS
Phase
compensation
circuit
Soft start built-in
reference power
supply
IC internal
power supply
+
−
Figure 1
(2) A and H Types (With Shutdown Function)
CONT VOUT
Oscillation circuit
PWMcontrol circuit
or PWM / PFM
swiching control
circuit
VSS
OFF/ON
Soft start built-in
reference power
supply
Phase
compensation
circuit
IC internal
power supply
+
−
Figure 2
(3) D and J Types (VDD / VOUT Separate Type)
CONT VOUTVDD
Oscillation circuit
PWMcontrol circuit
or PWM / PFM
swiching control
circuit
VSS
IC internal
power supply
Soft start built-in
reference power
supply
Phase
compensation
circuit
+
−
Figure 3
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 3
Product Name Structure
The control system, product types, output voltage, and packages for the S-8353/8354 Series can be selected at the
user’s request. Please refer to the “3. Product Name” for the definition of the product name and “4. Product Name
List” for the full product names.
1. Function List
(1) PWM Control Products
Table 1
Product Name
Switching
Frequency
kHz
Shutdown
Function
VDD / VOUT
Separate
Type
Package Application
S-8353AxxMC 50 Yes − SOT-23-5 Applications requiring shutdown function
S-8353AxxMA 50 − − SOT-23-3 Applications not requiring shutdown function
S-8353AxxUA 50 − − SOT-89-3 Applications not requiring shutdown function
S-8353CxxMA 30 − − SOT-23-3 For pager
S-8353DxxMC 50 − Yes SOT-23-5
Applications requiring variable output voltage
with an external resistor
S-8353HxxMC 250 Yes − SOT-23-5
Applications requiring a shutdown function
and a thin coil
S-8353HxxMA 250 − − SOT-23-3
Applications not requiring a shutdown function
and requiring a thin coil
S-8353HxxUA 250 − − SOT-89-3
Applications not requiring a shutdown function
and requiring a thin coil
S-8353JxxMC 250 − Yes SOT-23-5
Applications requiring variable output voltage
with an external resistor and a thin coil
(2) PWM / PFM Switching Control Products
Table 2
Product Name
Switching
Frequency
kHz
Shutdown
Function
VDD / VOUT
Separate
Type
Package Application
S-8354AxxMC 50 Yes − SOT-23-5 Applications requiring shutdown function
S-8354AxxMA 50 − − SOT-23-3 Applications not requiring shutdown function
S-8354AxxUA 50 − − SOT-89-3 Applications not requiring shutdown function
S-8354CxxMA 30 − − SOT-23-3 For pager
S-8354DxxMC 50 − Yes SOT-23-5
Applications requiring variable output voltage
with an external resistor
S-8354HxxMC 250 Yes − SOT-23-5
Applications requiring a shutdown function
and a thin coil
S-8354HxxMA 250 − − SOT-23-3
Applications not requiring a shutdown function
and requiring a thin coil
S-8354HxxUA 250 − − SOT-89-3
Applications not requiring a shutdown function
and requiring a thin coil
S-8354JxxMC 250 − Yes SOT-23-5
Applications requiring variable output voltage
with an external resistor and a thin coil
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
4
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
MC Yes S-8353 Series,
S-8354 Series
A (Normal product or with shutdown function)
A = 50 kHz MA / UA No No
C (Normal product)
C = 30 kHz MA No No
D (VDD / VOUT separate type)
D = 50 kHz MC No Yes
MC Yes
H (Normal product or with shutdown
function)
H = 250 kHz MA / UA No
No
J (VDD / VOUT separate type)
J = 250 kHz MC No Yes
3. Product Name
S-835 x x xx xx - xxx - T2
IC direction in tape specifications *1
Product code *2
Package code
MA : SOT-23-3
MC : SOT-23-5
UA : SOT-89-3
Output voltage
15 to 65
(e.g. When the output voltage is 1.5 V, it is expressed as 15.)
Product type
A : Normal products (SOT-23-3, SOT-89-3)
or With shutdown function products (SOT-23-5), fOSC = 50 kHz
C : Normal products, fOSC = 30 kHz
D : VDD / VOUT separate type, fOSC = 50 kHz
H : Normal products (SOT-23-3, SOT-89-3)
or With shutdown function products (SOT-23-5), fOSC = 250 kHz
J : VDD / VOUT separate type, fOSC = 250 kHz
Control system
3 : PWM control
4 : PWM / PFM switching control
*1. Refer to the taping specifications.
*2. Refer to the Table 4 to Table 7 in the “4. Product Name List”.
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 5
4. Product Name List
(1) S-8353 Series
Table 4
Output
voltage
S-8353AxxMC
Series
S-8353AxxMA
Series
S-8353AxxUA
Series
S-8353CxxMA
Series
2.0 V S-8353A20MC-IQF-T2 − − −
2.5 V S-8353A25MC-IQK-T2 − − −
2.7 V S-8353A27MC-IQM-T2 − − −
2.8 V S-8353A28MC-IQN-T2 − − −
3.0 V S-8353A30MC-IQP-T2 S-8353A30MA-IQP-T2 − S-8353C30MA-ISP-T2
3.3 V S-8353A33MC-IQS-T2 S-8353A33MA-IQS-T2 S-8353A33UA-IQS-T2 −
3.6 V − − S-8353A36UA-IQV-T2 −
3.8 V S-8353A38MC-IQX-T2 − − −
4.0 V − − S-8353A40UA-IQZ-T2 −
4.5 V S-8353A45MC-IRE-T2 − − −
5.0 V S-8353A50MC-IRJ-T2 S-8353A50MA-IRJ-T2 S-8353A50UA-IRJ-T2 −
5.5 V S-8353A55MC-IRO-T2 − S-8353A55UA-IRO-T2 −
Remark Please contact the SII marketing department for products with an output voltage other than those specified above.
Table 5
Output
voltage
S-8353DxxMC
Series
S-8353HxxMC
Series
S-8353HxxUA
Series
S-8353JxxMC
Series
2.0 V S-8353D20MC-IUF-T2 − − S-8353J20MC-IYF-T2
2.5 V − − − S-8353J25MC-IYK-T2
3.0 V S-8353D30MC-IUP-T2 S-8353H30MC-IWP-T2 − S-8353J30MC-IYP-T2
3.1 V − S-8353H31MC-IWQ-T2 − −
3.2 V − S-8353H32MC-IWR-T2 − −
3.3 V − S-8353H33MC-IWS-T2 S-8353H33UA-IWS-T2 −
3.5 V − S-8353H35MC-IWV-T2 − −
3.8 V − S-8353H38MC-IWX-T2 − −
4.0 V − S-8353H40MC-IWZ-T2 − −
4.5 V − S-8353H45MC-IXE-T2 − −
5.0 V S-8353D50MC-IVJ-T2 S-8353H50MC-IXJ-T2 − S-8353J50MC-IZJ-T2
Remark Please contact the SII marketing department for products with an output voltage other than those specified above.
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
6
(2) S-8354 Series
Table 6
Output
voltage
S-8354AxxMC
Series
S-8354AxxMA
Series
S-8354AxxUA
Series
S-8354DxxMC
Series
2.0 V − − − S-8354D20MC-JUF-T2
2.7 V S-8354A27MC-JQM-T2 S-8354A27MA-JQM-T2 − −
3.0 V S-8354A30MC-JQP-T2 S-8354A30MA-JQP-T2 S-8354A30UA-JQP-T2 −
3.3 V S-8354A33MC-JQS-T2 S-8354A33MA-JQS-T2 S-8354A33UA-JQS-T2 −
3.5 V − − S-8354A35UA-JQV-T2 −
4.0 V S-8354A40MC-JQZ-T2 − S-8354A40UA-JQZ-T2 −
5.0 V S-8354A50MC-JRJ-T2 S-8354A50MA-JRJ-T2 S-8354A50UA-JRJ-T2 −
Remark Please contact the SII marketing department for products with an output voltage other than those specified above.
Table 7
Output
voltage
S-8354HxxMC
Series
S-8354JxxMC
Series
2.5 V S-8354H25MC-JWK-T2 −
3.0 V S-8354H30MC-JWP-T2 S-8354J30MC-JYP-T2
3.3 V S-8354H33MC-JWS-T2 −
5.0 V S-8354H50MC-JXJ-T2 S-8354J50MC-JZJ-T2
Remark Please contact the SII marketing department for products with an output voltage other than those specified above.
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 7
Pin Configurations
Table 8
A, C and H 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
1
3 2
SOT-23-3
Top view
Figure 4
Table 9
A and H Types
(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
Figure 5 *1. The NC pin indicates electrically open.
Table 10
D and J Types
(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
*1. The NC pin indicates electrically open.
Table 11
A and H Types
(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
SOT-89-3
Top view
3
2 1
Figure 6
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
8
Absolute Maximum Ratings
Table 12
(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 (A type) *1 OFF/ON
V VSS − 0.3 to VSS + 12 V
VDD pin voltage (D type)*2 VDD V
SS − 0.3 to VSS + 12 V
CONT pin voltage VCONT V
SS − 0.3 to VSS + 12 V
CONT pin current ICONT 300 mA
Power dissipation SOT-23-3 PD 150 mW
SOT-23-5 250 mW
SOT-89-3 500 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
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.
050 100 150
600
400
0
Power dissipation (PD) [mW]
Ambient temperature (Ta) [°C]
SOT-23-3
SOT-89-3
SOT-23-5
200
Figure 7 Power Dissipation of The Packages (Before Mounting)
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 9
Electrical Characteristics
(1) 50 kHz Product (A and D Types)
Table 13
(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 2
Input voltage V
IN
−
−
−
10 V 2
Operation start voltage V
ST1
I
OUT
= 1 mA
−
−
0.9 V 2
Oscillation start voltage V
ST2
No external parts, Voltage applied to V
OUT
−
−
0.8 V 1
Operation holding voltage V
HLD
I
OUT
= 1 mA, Judged by decreasing V
IN
voltage gradually 0.7
−
−
V 2
Current consumption 1 I
SS1
V
OUT
= V
OUT(S)
×
0.95 S-835xx15 to 19
−
10.8 18.0
µ
A 1
S-835xx20 to 29
−
13.3 22.2
µ
A 1
S-835xx30 to 39
−
18.7 31.1
µ
A 1
S-835xx40 to 49
−
24.7 41.1
µ
A 1
S-835xx50 to 59
−
31.0 51.6
µ
A 1
S-835xx60 to 65
−
37.8 63.0
µ
A 1
Current consumption 2 I
SS2
V
OUT
= V
OUT(S)
+
0.5 V S-835xx15 to 19
−
4.8 9.5
µ
A 1
S-835xx20 to 29
−
5.0 9.9
µ
A 1
S-835xx30 to 39
−
5.1 10.2
µ
A 1
S-835xx40 to 49
−
5.3 10.6
µ
A 1
S-835xx50 to 59
−
5.5 10.9
µ
A 1
S-835xx60 to 65
−
5.7 11.3
µ
A 1
Current consumption during
shutdown
(With shutdown function)
I
SSS
OFF/ON
V
= 0 V
−
−
0.5
µ
A 1
Switching current I
SW
V
CONT
= 0.4 V S-835xx15 to 19 80 128
−
mA 1
S-835xx20 to 24 103 165
−
mA 1
S-835xx25 to 29 125 200
−
mA 1
S-835xx30 to 39 144 231
−
mA 1
S-835xx40 to 49 176 282
−
mA 1
S-835xx50 to 59 200 320
−
mA 1
S-835xx60 to 65 215 344
−
mA 1
Switching transistor leakage
current I
SWQ
V
CONT
= V
OUT
= 10 V
−
−
0.5
µ
A 1
Line regulation
∆
V
OUT1
V
IN
= V
OUT(S)
×
0.4 to
×
0.6
−
30 60 mV 2
Load regulation
∆
V
OUT2
I
OUT
= 10
µ
A to V
OUT(S)
/ 250
×
1.25
−
30 60 mV 2
Output voltage temperature
coefficient
OUT
OUT
VTa∆
V∆
•
Ta =
−
40 to
+
85
°
C
−
±
50
−
ppm /
°
C 2
Oscillation frequency f
OSC
V
OUT
= V
OUT(S)
×
0.95 42.5 50 57.5 kHz 1
Maximum duty ratio MaxDuty V
OUT
= V
OUT(S)
×
0.95 75 83 90 % 1
PWM / PFM switching duty
ratio (For S-8354 Series) PFMDuty V
IN
= V
OUT(S)
−
0.1 V, No-load 10 15 24 % 1
V
SH
Measured oscillation at CONT pin 0.75
−
−
V 1
V
SL1
At V
OUT
≥
1.5 V
−
−
0.3 V 1
OFF/ON
pin input voltage
(With shutdown function) V
SL2
Judged oscillation stop at
CONT pin At V
OUT
<
1.5 V
−
−
0.2 V 1
I
SH
OFF/ON
V
= V
OUT(S)
×
0.95
−
0.1
−
0.1
µ
A 1
OFF/ON
pin input current
(With shutdown function) I
SL
OFF/ON
V
= 0 V
−
0.1
−
0.1
µ
A 1
Soft start time t
SS
−
3.0 6.0 12.0 ms 2
Efficiency EFFI
−
−
85
−
% 2
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
10
External parts
Coil: CDRH6D28-101 of Sumida Corporation
Diode: MA2Z748 (Shottky type) of Matsushita Electric Industrial Co., Ltd.
Capacitor: F93 (16 V, 22 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 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.)
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 11
(2) 30 kHz Product (C Type)
Table 14
(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 2
Input voltage V
IN
−
−
−
10 V 2
Operation start voltage V
ST1
I
OUT
= 1 mA
−
−
0.9 V 2
Oscillation start voltage V
ST2
No external parts, Voltage applied to V
OUT
−
−
0.8 V 1
Operation holding voltage V
HLD
I
OUT
= 1 mA, Judged by decreasing V
IN
voltage gradually 0.7
−
−
V 2
Current consumption 1 I
SS1
V
OUT
= V
OUT(S)
×
0.95 S-835xx20 to 29
−
9.8 16.4
µ
A 1
S-835xx30 to 39
−
13.1 21.9
µ
A 1
S-835xx40 to 49
−
16.8 28.0
µ
A 1
S-835xx50 to 59
−
20.7 34.5
µ
A 1
S-835xx60 to 65
−
24.8 41.4
µ
A 1
Current consumption 2 I
SS2
V
OUT
= V
OUT(S)
+
0.5 V S-835xx20 to 29
−
435 9.0
µ
A 1
S-835xx30 to 39
−
4.7 9.4
µ
A 1
S-835xx40 to 49
−
4.9 9.7
µ
A 1
S-835xx50 to 59
−
5.1 10.1
µ
A 1
S-835xx60 to 65
−
5.2 10.4
µ
A 1
Switching current I
SW
V
CONT
= 0.4 V S-835xx20 to 24 52 83
−
mA 1
S-835xx25 to 29 62 100
−
mA 1
S-835xx30 to 39 72 115
−
mA 1
S-835xx40 to 49 88 141
−
mA 1
S-835xx50 to 59 100 160
−
mA 1
S-835xx60 to 65 108 172
−
mA 1
Switching transistor leakage
current I
SWQ
V
CONT
= V
OUT
= 10 V
−
−
0.5
µ
A 1
Line regulation
∆
V
OUT1
V
IN
= V
OUT(S)
×
0.4 to
×
0.6
−
30 60 mV 2
Load regulation
∆
V
OUT2
I
OUT
= 10
µ
A to V
OUT(S)
/ 250
×
1.25
−
30 60 mV 2
Output voltage temperature
coefficient
OUT
OUT
VTa∆
V∆
•
Ta =
−
40 to
+
85
°
C
−
±
50
−
ppm /
°
C 2
Oscillation frequency f
OSC
V
OUT
= V
OUT(S)
×
0.95 25 30 35 kHz 1
Maximum duty ratio MaxDuty V
OUT
= V
OUT(S)
×
0.95 75 83 90 % 1
PWM / PFM switching duty
ratio (For S-8354 Series) PFMDuty V
IN
= V
OUT(S)
−
0.1 V, No-load 10 15 24 % 1
Soft start time t
SS
−
3.0 6.0 12.0 ms 2
Efficiency EFFI
−
−
84
−
% 2
External parts
Coil: CDRH6D28-101 of Sumida Corporation
Diode: MA2Z748 (Shottky type) of Matsushita Electric Industrial Co., Ltd.
Capacitor: F93 (16 V, 22 µF tantalum type) of Nichicon Corporation
VIN = VOUT(S) × 0.6 applied, IOUT = VOUT(S) / 250 Ω
Remark VOUT(S) specified above is the set output voltage value, and VOUT is the typical value of the actual output voltage.
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
12
(3) 250 kHz Product (H and J Types)
Table 15
(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 2
Input voltage V
IN
−
−
−
10 V 2
Operation start voltage V
ST1
I
OUT
= 1 mA
−
−
0.9 V 2
Oscillation start voltage V
ST2
No external parts, Voltage applied to V
OUT
−
−
0.8 V 1
Operation holding voltage V
HLD
I
OUT
= 1 mA, Judged by decreasing V
IN
voltage gradually 0.7
−
−
V 2
Current consumption 1 I
SS1
V
OUT
= V
OUT(S)
×
0.95 S-835xx15 to 19
−
36.5 60.8
µ
A 1
S-835xx20 to 29
−
48.3 80.5
µ
A 1
S-835xx30 to 39
−
74.3 123.8
µ
A 1
S-835xx40 to 49
−
103.1 171.9
µ
A 1
S-835xx50 to 59
−
134.1 223.5
µ
A 1
S-835xx60 to 65
−
167.0 278.4
µ
A 1
Current consumption 2 I
SS2
V
OUT
= V
OUT(S)
+
0.5 V S-835xx15 to 19
−
9.1 18.2
µ
A 1
S-835xx20 to 29
−
9.3 18.6
µ
A 1
S-835xx30 to 39
−
9.5 18.9
µ
A 1
S-835xx40 to 49
−
9.7 19.3
µ
A 1
S-835xx50 to 59
−
9.8 19.6
µ
A 1
S-835xx60 to 65
−
10.0 19.9
µ
A 1
Current consumption during
shutdown
(With shutdown function)
I
SSS
OFF/ON
V
= 0 V
−
−
0.5
µ
A 1
Switching current I
SW
V
CONT
= 0.4 V S-835xx15 to 19 80 128
−
mA 1
S-835xx20 to 24 103 165
−
mA 1
S-835xx25 to 29 125 200
−
mA 1
S-835xx30 to 39 144 231
−
mA 1
S-835xx40 to 49 176 282
−
mA 1
S-835xx50 to 59 200 320
−
mA 1
S-835xx60 to 65 215 344
−
mA 1
Switching transistor leakage
current I
SWQ
V
CONT
= V
OUT
= 10 V
−
−
0.5
µ
A 1
Line regulation
∆
V
OUT1
V
IN
= V
OUT(S)
×
0.4 to
×
0.6
−
30 60 mV 2
Load regulation
∆
V
OUT2
I
OUT
= 10
µ
A to V
OUT(S)
/ 250
×
1.25
−
30 60 mV 2
Output voltage temperature
coefficient
OUT
OUT
VTa
V
•∆
∆
Ta =
−
40 to
+
85
°
C
−
±
50
−
ppm /
°
C 2
Oscillation frequency f
OSC
V
OUT
= V
OUT(S)
×
0.95 212.5 250 287.5 kHz 1
Maximum duty ratio MaxDuty V
OUT
= V
OUT(S)
×
0.95 70 78 85 % 1
PWM / PFM switching duty
ratio (For S-8354 Series) PFMDuty V
IN
= V
OUT(S)
−
0.1 V, No-load 10 15 24 % 1
V
SH
Measured oscillation at CONT pin 0.75
−
−
V 1
V
SL1
At V
OUT
≥
1.5 V
−
−
0.3 V 1
OFF/ON
pin input voltage
(With shutdown function) V
SL2
Judged oscillation stop at
CONT pin At V
OUT
<
1.5 V
−
−
0.2 V 1
I
SH
OFF/ON
V
= V
OUT(S)
×
0.95
−
0.1
−
0.1
µ
A 1
OFF/ON
pin input current
(With shutdown function) I
SL
OFF/ON
V
= 0 V
−
0.1
−
0.1
µ
A 1
Soft start time t
SS
−
1.8 3.6 7.2 ms 2
Efficiency EFFI
−
−
85
−
% 2
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 13
External parts
Coil: CDRH6D28-220 of Sumida Corporation
Diode: MA2Z748 (Shottky type) of Matsushita Electric Industrial Co., Ltd.
Capacitor: F93 (16 V, 22 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 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.)
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
14
Measurement Circuits
1.
300 Ω
A
VSS
VOUT
CONT
VDD
*2
0.1 µF
+
−
OFF/ON
*1
Oscilloscope
Figure 8
2.
V
VSS
CONT VOUT
VDD
*2
0.1 µF
+
−
+
−
OFF/ON
*1
Figure 9
*1. With shutdown function
*2. For VDD / VOUT separate type
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 15
Operation
1. Switching Control Types
1.1 PWM Control (S-8353 Series)
The S-8353 Series is a DC-DC converter using a pulse width modulation method (PWM) and features low current
consumption. In conventional PFM DC-DC converters, pulses are skipped when the output load current is low,
causing a fluctuation in the ripple frequency of the output voltage, resulting in an increase in the ripple voltage.
In the S-8353 Series, the switching frequency does not change, although the pulse width changes from 0 to 83%
(78% for H and J type) corresponding to each load current. The ripple voltage generated from switching can thus
be removed easily using a filter because the switching frequency is constant.
1.2 PWM / PFM Switching Control (S-8354 Series)
The S-8354 Series is a DC-DC converter that automatically switches between a pulse width modulation method
(PWM) and a pulse frequency modulation method (PFM), depending on the load current, and features low current
consumption.
The S-8354 Series operates under PWM control with the pulse width duty changing from 15 to 83 % (78% for H
and J type) in a high output load current area. On the other hand, the S-8354 Series operates under PFM control
with the pulse width duty fixed at 15% in a low output load current area, and pulses are skipped according to the
load current. The oscillation circuit thus oscillates intermittently so that the resultant lower self current
consumption can prevent a reduction in the efficiency at a low load current. The switching point from PWM
control to PFM control depends on the external devices (coil, diode, etc.), input voltage, and output voltage. This
series are an especially efficient DC-DC converter at an output current around 100 µA.
2. Soft Start Function
For this IC, a built-in soft start circuit controls the rush current and overshoot of the output voltage when the power
is turned on or the OFF/ON pin is set to “H” level.
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
16
3. OFFON/ Pin (Shutdown Pin) (SOT-23-5 Package Products of A and H Types)
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 10 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 OFF/ON pin is not used, connect it to the VOUT
pin.
The OFF/ON pin does not have hysteresis.
Table 16
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 10 OFFON/ Pin Structure
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 17
4. Operation
The following are the basic equations [(1) through (7)] of the step-up switching regulator. (Refer to Figure 11.)
C
L
M1
D
VOUT
CONT
VIN
L
+
EXT
VSS
−
Figure 11 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 :
L
VV
L
V
dt
dI SINLL −
== (2)
Integration of equation (2) (IL) :
t
L
VV
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
L
VV
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 (VL) 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 (IL) flowing through the diode into VOUT during tOFF :
L
VVV
L
V
dt
dI INDOUTLL −+
== (6)
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
18
Integration of the equation (6) is as follows :
t
L
VVV
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
L
VVV
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 ∆Q1 which is charged in CL during t1 :
2
1
INDOUT
1PK
1t
0
INDOUT
1t
0
PKL
1t
0
1t
2
1
L
VVV
tItdt
L
VVV
dtIdtIQ •
−+
−•=•
−+
−•==∆ ∫∫∫ (12)
When substituting equation (12) for equation (9) :
()
1
OUTPK
1OUTPKPK t
2
II
tII
2
1
I1Q •
+
=•−−=∆ (13)
A rise in voltage (VP−P) due to ∆Q 1 :
1
OUTPK
LL
1
PP t
2
II
C
1
C
Q∆
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 C
tI
R
2
II
1t
2
II
C
1
C
Q
V•
−•
+
+•
+
•=
∆
=
− (15)
When substituting equation (11) for equation (15) :
ESR
OUTPK
L
OFF
PK
2
OUTPK
PP R
2
II
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, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 19
External Parts Selection
The relationship between the major characteristics of the step-up circuit and the characteristic parameters of the external
parts is shown in Figure 12.
For higher efficiency ?
For larger output current ?
At PFM control At PWM control
For smaller ripple voltage ?
Smaller inductance
Larger inductance
Smaller direct current resistance of inductor
Larger output capacitance
Larger output capacitance
Figure 12 Relationship between Major Characteristics of Step-up Circuit and External Parts
1. Inductor
The inductance value (L value) has a strong influence on the maximum output current (IOUT) and efficiency (η).
The peak current (IPK) increases by decreasing L value and the stability of the circuit improves and IOUT increases. If L
value is decreased, the efficiency falls causing a decline in the current drive capacity for the switching transistor, and
IOUT decreases.
The loss of IPK by the switching transistor decreases by increasing L and the efficiency becomes maximum at a
certain L value. Further increasing L value decreases the efficiency due to the loss of the direct current resistance of
the coil. IOUT also decreases.
A higher oscillation frequency allows selection of a lower L value, making the coil smaller.
The recommended inductances are a 47 to 220 µH for A, C, and D types, a 10 to 47 µH for H and J types.
Be careful of the allowable inductor current when choosing an inductor. Exceeding the allowable current of the
inductor causes magnetic saturation, much lower efficiency and destruction of the IC chip due to a large current.
Choose an inductor so that IPK does not exceed the allowable current. IPK in discontinuous mode is calculated by the
following equation:
Lf
)VVV(I 2
I
OSC
INDOUT
OUT
PK •
−+
= (A) (17)
fosc = oscillation frequency, VD ≅ 0.4 V.
2. Diode
Use an external diode that meets the following requirements :
• Low forward voltage : VF < 0.3 V
• High switching speed : 50 ns max.
• Reverse voltage : VOUT + VF or more
• Current rate : IPK or more
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
20
3. Capacitor (CIN, CL)
A capacitor on the input side (CIN) improves the efficiency by reducing the power impedance and stabilizing 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.
Select an appropriate capacitor the equivalent series resistance (RESR) for stable output voltage. The stable voltage
range in this IC depends on the RESR. Although the inductance value (L value) is also a factor, an RESR of 30 to 500
mΩ maximizes the characteristics. However, the best RESR value may depend on the L value, the capacitance, the
wiring, and the applications (output load). Therefore, fully evaluate the RESR under the actual operating conditions to
determine the best value.
Refer to the “1. Example of Ceramic Capacitor Application” (Figure 16) in the “ Application Circuit” for the
circuit example using a ceramic capacitor and the external resistance of the capacitor (RESR).
5. VDD / VOUT Separate Type (D and J Types)
The D and J types 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) When changing the output voltage with external resistance.
(2) When outputting a high voltage within the operating voltage (10 V).
Choose the products in the Table 17 according to the applications (1) or (2) above.
Table 17
Output voltage (VCC) 1.8 V ≤ VCC < 5 V 5 V ≤ VCC ≤ 10 V
S-835xx18 Yes −
S-835xx50 − Yes
Connection to VDD pin VIN or VCC V
IN
Cautions 1. This IC starts a step-up operation at VDD = 0.8 V, but 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 with 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 there
is impedance between the VOUT pin and VSS pin in the IC chip. The internal resistance
between the VOUT pin and VSS pin is as follows :
(1) S-835xx18 : 2.1 to 14.8 MΩ
(2) S-835xx20 : 1.4 to 14.8 MΩ
(3) S-835xx30 : 1.4 to 14.2 MΩ
(4) S-835xx50 : 1.4 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
C
A
C•••
=π
F
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 21
Standard Circuits
(1) S-8353AxxMA / UA, S-8353CxxMA, S-8353HxxMA/UA, S-8354AxxMA/UA, S-8354CxxMA, S-8354HxxMA / UA
C
L
SD
V
IN
L VOUT
VSS
PWM control circuit
or PWM / PFM
switching control
circuit
Phase
compensating
circuit
C
IN
CONT
Oscillation circuit
Soft start built-in
reference power
supply
+
−
+
−
+
−
IC internal
power
supply
Remark The power supply for the IC chip is from the VOUT pin.
Figure 13
(2) S-8353AxxMC, S-8353HxxMC, S-8354AxxMC, S-8354HxxMC
PWM control circuit
or PWM / PFM
switching control
circuit
Phase
compensating
circuit
Oscillation circuit
SD
V
IN
L VOUT
VSS
C
IN
C
L
CONT
OFF/ON
Soft start built-in
reference power
supply
−
+
+
−
+
−
IC internal
power
supply
Remark The power supply for the IC chip is from the VOUT pin.
Figure 14
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
22
(3) S-8353DxxMC, S-8353JxxMC, S-8354DxxMC, S-8354JxxMC
L
SD
V
IN
C
IN
VDD
Soft start built-in
reference power
supply
Phase
compensating
circuit
Oscillation
circuit
PWM control circuit
or PWM / PFM
switching control
circuit
CONT
VSS
R
B
R
A
C
C
VOUT
C
L
+
−
+
−
+
−
IC internal
power
supply
Remark The power supply for the IC chip is from the VOUT pin.
Figure 15
Caution The Above connection diagram will not guarantee successful operation. Perform through
evaluation using the actual application to set the constant.
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 23
Precautions
• Mount external capacitors, diodes, and coils as close as possible to the IC. Especially, mounting the output capacitor
(capacitor between VDD pin and VSS pin for VDD / VOUT separate type) in the power supply line of the IC close to the IC
can enable stable output characteristics. If it is impossible, it is recommended to mount and wire a ceramic capacitor
of around 0.1 µF close 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 these largely depend on the coil, the capacitor and impedance of
power supply 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. The recommended external part should be used wherever possible, but if
this is not possible for some reason, contact an SII sales person.
• Do not apply an electrostatic discharge to this IC that exceeds the performance ratings of the built-in electrostatic
protection circuit.
• 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 a third party.
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
24
Application Circuits
1. Using Ceramic Capacitor Example
When using small RESR parts such as ceramic capacitors for the output capacitance, mount a resistor (R1)
corresponding to the RESR in series with the ceramic capacitor (CL) as shown in Figure 16.
R1 differs depending on L value, the capacitance, the wiring, and the application (output load).
The following example shows a circuit using R1 = 100 mΩ, output voltage = 3.3 V, output load = 100 mA and its
characteristics.
CONT VOUT
VSS
VOUT
SD
CL
L
R1
VIN CIN
Figure 16 Using Ceramic Capacitor Circuit Example
Table 18
IC L Type Name SD Type Name CL
(Ceramic capacitor) R1
S-8353A33 CDRH5D28-101 MA2Z748 10 µF × 2 100 mΩ
Caution The Above connection diagram and constant will not guarantee successful operation. Perform
through evaluation using the actual application to set the constant.
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 25
2. Output Characteristics of The Using Ceramic Capacitor Circuit Example
The data of the step-up characteristics (a) Output current (IOUT) vs. Efficiency (η) characteristics, (b) Output current
(IOUT) vs. Output voltage (VOUT) characteristics, (c) Output Current (IOUT) vs. Ripple voltage (Vr) under conditions in
Table 18 is shown below.
(a) Output current (IOUT) vs. Efficiency (η) (b) Output current (IOUT) vs. Output voltage (VOUT)
V
IN
=1.8 V
V
IN
=2.7 V
V
IN
=0.9 V
0
20
40
60
80
100
0.01 0.1 1 10 100 1000
I
OUT
[mA]
η [%]
3.20
3.25
3.30
3.35
3.40
0.01 0.1 1 10 100 1000
I
OUT
[mA]
V
OUT
[V]
V
IN
=1.8 V
V
IN
=2.7 V
V
IN
=0.9 V
(c) Output current (IOUT) vs. Ripple voltage (Vr)
0
20
40
60
80
100
120
0.01 0.1 1 10 100 1000
V
r
[mV]
I
OUT
[mA]
140
V
IN
= 1.8 V
V
IN
= 2.7 V
V
IN
= 0.9 V
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
S-8353/8354 Series Rev.1.4_00
Seiko Instruments Inc.
26
Characteristics (Typical Data)
1. Example of Major Temperature characteristics (Ta = − 40 to + 85 °C, VOUT = 3.3 V)
(1) Current Consumption 1 (ISS1) vs. Temperature (Ta)
fOSC = 50 kHz fOSC = 250 kHz
0
10
20
30
40
50
−40 −20 0 20 40 60 80 100
Ta [°C]
I
SS1
[µA]
0
10
20
30
40
50
I
SS1
[µA]
−40 −20 0 20 40 60 80 100
Ta [°C]
(2) Current Consumption 2 (ISS2) vs. Temperature (Ta)
fOSC = 50 kHz fOSC = 250 kHz
0
2
4
6
8
10
−40 −20 0 20 40 60 80
100
Ta [°C]
I
SS2
[µA]
0
2
4
6
8
10
−40 −20 0 20 40 60 80 100
Ta [°C]
I
SS2
[µA]
(3) Current Consumption at Shutdown (ISSS) vs. Temperature (Ta)
fOSC = 250 kHz
0
0.2
0.4
0.6
0.8
1.0
−40 −20 0 20 40 60 80 100
Ta [°C]
I
SSS
[µA]
(4) Switching Current (I
SW
) vs. Temperature (Ta) (5) Switching Transistor Leakage Current (I
SWQ
) vs. Temperature (Ta)
fOSC = 250 kHz fOSC = 250 kHz
−40 −20 0 20 40 60 80 100
Ta [°C]
ISW [mA]
100
200
300
400
500
0
0
0.2
0.4
0.6
0.8
1.0
−40 −20 0 20 40 60 80 100
Ta [°C]
I
SWQ
[
µ
A]
STEP-UP, PWM CONTROL or PWM / PFM SWITCHABLE BUILT-IN TRANSISTOR SWITCHING REGULATOR
Rev.1.4_00 S-8353/8354 Series
Seiko Instruments Inc. 27
(6) Oscillation Frequency (fOSC) vs. Temperature (Ta)
fOSC = 50 kHz fOSC = 250 kHz
30
40
50
60
70
−40 −20 0 20 40 60 80 100
Ta [°C]
f
OSC
[kHz]
150
200
250
300
350
−40 −20 0 20 40 60 80 100
f
OSC
[kHz]
Ta [°C]
(7) Maximum Duty Ratio (MaxDuty) vs. Temperature (Ta)
fOSC = 50 kHz fOSC = 250 kHz
−40 −20 0 20 40 60 80 100
Ta [°C]
MaxDuty [%]
50
60
70
80
90
100
−40 −20 0 20 40 60 80 100
Ta [°C]
MaxDuty [%]
50
60
70
80
90
100
(8) PWM / PFM Switching Duty Ratio (PFMDuty) vs.
Temperature (Ta) (S-8354 Series)
(9) OFF/ON Pin Input Voltage “H” (VSH) vs.
Temperature (Ta)
fOSC = 250 kHz fOSC = 250 kHz
5
10
15
20
25
−40 −20 0 20 40 60 80 100
Ta [°C]
PFMDuty [%]
0
0.2
0.4
0.6
0.8
1.0
−40 −20 0 20 40 60 80 100
Ta [°C]
V
SH
[V]
(10) OFF/ON Pin Input Voltage “L” 1 (VSL1) vs.
Temperature (Ta) (S-8354 Series)
(11) OFF/ON Pin Input Voltage “L” 2 (VSL2) vs.
Temperatuer (Ta)
fOSC = 250 kHz fOSC = 250 kHz
0
0.2
0.4
0.6
0.8
1.0
−40 −20 0 20 40 60 80 100
V
SL1
[V]
Ta [°C]
0
0.2
0.4
0.6
0.8
1.0
−40 −20 0 20 40 60 80 100
Ta [°C]
V
SL2
[V]
