S-8520/8521 Series
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© Seiko Instruments Inc., 1997-2010
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE
SWITCHING REGULATOR CONTROLLER
Rev.9.0
_00
The S-8520/8521 Series is a CMOS step-down switching regulator-controller with PWM control (S-8520 Series) and PWM
/ PFM switching control (S-8521 Series). The S-8520/8521 Series has a reference voltage source, an oscillation circuit, an
error amplifier, and other components.
The S-8520 Series provides low-ripple power, high efficiency, and excellent transient characteristics due to a PWM control
circuit capable of varying the duty ratio linearly from 0% up to 100%. The S-8520/8521 Series also has a soft-start circuit
that prevents overshoot at startup.
The S-8521 Series works with either PWM control or PFM control. It normally operates using PWM control with a duty ratio
of 25% to 100%, but under a light load, it automatically switches to PFM control with a duty ratio of 25%. The S-8520/8521
Series ensures high efficiency over a wide range of conditions for devices, from the standby mode to the operation.
By adding external Pch power MOS FET or PNP transistor, coil, capacitor, and externally connected diode, the
S-8520/8521 Series can function as a step-down switching regulator, and is ideal for power supply units of portable
devices due to small SOT-23-5 and the feature of low current consumption. It is also ideal for AC adapters due to the input
voltage up to 16 V.
Features
•
Low current consumption
60
μA
max. (A, B types)
21
μA
max. (C, D types)
100
μA
max. (E, F types)
During shutdown: 0.5
μA
max.
Input voltage:
2.5 V to 16 V (B, D, F types)
2.5 V to 10 V (A, C, E types)
Output voltage:
Selectable between 1.5 V and 6.0 V in 0.1 V step
Duty ratio:
0% to 100% PWM control (S-8520 Series)
25% to100% PWM / PFM switching control (S-8521 Series)
External parts are Pch power MOS FET or PNP transistor, coil, diode, and capacitor only
(When using PNP transistor, add base resistor and capacitor).
Oscillation frequency:
180 kHz typ. (A, B types)
60 kHz typ. (C, D types)
300 kHz typ. (E, F types)
Soft-start function:
8 ms. typ.
(A, B types)
12 ms. typ. (C, D types)
4.5 ms. typ. (E, F types)
With a shutdown function
With a built-in overload protection circuit Overload detection time:
4 ms. typ.
(A type)
14 ms. typ. (C type)
2.6 ms. typ. (E type)
*1
Lead-free, Sn 100%, halogen-free
During operation:
Product Name Structure”
for details.
•
•
•
•
•
•
•
•
•
*1.
Refer to “
Seiko Instruments Inc.
1
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
Rev.9.0
_00
S-8520/8521 Series
Applications
•
•
•
•
•
•
On-board power supplies of battery devices for mobile phone, electronic notebooks, PDAs.
Power supplies for audio equipment, including portable CD players and headphone stereo equipment.
Fixed voltage power supply for cameras, video and communication devices.
Power supplies for microcomputers
Conversion from NiH or four NiCd cells or two lithium-ion cells to 3.3 V / 3 V.
Conversion of AC adapter input to 5 V / 3 V.
Package
•
SOT-23-5
2
Seiko Instruments Inc.
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
Rev.9.0
_00
S-8520/8521 Series
Block Diagrams
1.
S-8520 Series
L
Tr
VIN
Oscillation
circuit
Reference voltage
source with soft-start VOUT
+
−
+
C
OUT
EXT
V
IN
+
C
IN
SD
PWM control
circuit
V
ON/OFF
______
VSS
______
ON/OFF
Remark
All the diodes in the figure are parasitic diodes.
Figure 1
2.
S-8521 Series
L
Tr
VIN
Oscillation
circuit
Reference voltage
source with soft-start VOUT
+
−
+
C
OUT
EXT
V
IN
+
C
IN
SD
PWM / PFM switching
control circuit
V
ON/OFF
______
VSS
______
ON/OFF
Remark
All the diodes in the figure are parasitic diodes.
Figure 2
Seiko Instruments Inc.
3
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
Rev.9.0
_00
S-8520/8521 Series
Product Name Structure
The control types, product types, and output voltage for the S-8520/8521 Series can be selected at the user’s request.
Please refer to the “1.
Product name”
for the definition of the product name, “2.
Package”
regarding the package
drawings and “3.
Product name list”
for the full product names.
1.
Product name
x
x
xx
MC
−
xxx
T2
x
S-852
Environm ental code
U:
Lead-free (Sn 100% ), halogen-free
G:
Lead-free (for details, please contact our sales office)
IC direction in tape specifications
Product name (abbreviation)
*2
Package name (abbreviation)
MC : SO T-23-5
O utput voltage
15 to 60
(W hen the output voltage is 1.5 V, it is expressed as 15.)
Product type
A: Oscillation frequency of 180 kHz,
W ith overload protection circuit
B: Oscillation frequency of 180 kHz,
W ithout overload protection circuit
C: Oscillation frequency of 60 kHz,
W ith overload protection circuit
D: Oscillation frequency of 60 kHz,
W ithout overload protection circuit
E: Oscillation frequency of 300 kHz,
W ith overload protection circuit
F: Oscillation frequency of 300 kHz,
W ithout overload protection circuit
Control system
0: PW M control
1: PW M / PFM switching control
*1.
*2.
Refer to the tape specifications.
Refer to “3.
Product name list”.
*1
2.
Package
Package Name
SOT-23-5
Drawing code
Tape
MP005-A-C-SD
Package
MP005-A-P-SD
Reel
MP005-A-R-SD
4
Seiko Instruments Inc.
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
Rev.9.0
_00
S-8520/8521 Series
3.
Product name list
3. 1
S-8520 Series
Output voltage [V]
1.5
1.8
2.0
2.1
2.4
2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
3.5
3.6
4.0
4.3
5.0
5.3
Table 1 (1 / 2)
S-8520AxxMC Series
S-8520BxxMC Series
S-8520B15MC-ARAT2x
−
S-8520B18MC-ARDT2x
−
S-8520A20MC-AVFT2x
−
S-8520A21MC-AVGT2x
−
S-8520B24MC-ARJT2x
−
S-8520A25MC-AVKT2x
S-8520B25MC-ARKT2x
S-8520A26MC-AVLT2x
−
S-8520A27MC-AVMT2x
S-8520B27MC-ARMT2x
S-8520A28MC-AVNT2x
S-8520B28MC-ARNT2x
S-8520A29MC-AVOT2x
S-8520B29MC-AROT2x
S-8520A30MC-AVPT2x
S-8520B30MC-ARPT2x
S-8520A31MC-AVQT2x
S-8520B31MC-ARQT2x
S-8520A32MC-AVRT2x
S-8520B32MC-ARRT2x
S-8520A33MC-AVST2x
S-8520B33MC-ARST2x
S-8520A34MC-AVTT2x
S-8520B34MC-ARTT2x
S-8520A35MC-AVUT2x
S-8520B35MC-ARUT2x
S-8520A36MC-AVVT2x
S-8520B36MC-ARVT2x
S-8520B40MC-ARZT2x
−
S-8520B43MC-ASCT2x
−
S-8520A50MC-AWJT2x
S-8520B50MC-ASJT2x
S-8520B53MC-ASMT2x
−
Table 1 (2 / 2)
S-8520DxxMC Series
S-8520ExxMC Series
S-8520E15MC-BJAT2x
−
S-8520E16MC-BJBT2x
−
S-8520E18MC-BJDT2x
−
−
−
S-8520D25MC-BVKT2x
S-8520E25MC-BJKT2x
−
−
S-8520D27MC-BVMT2x
−
S-8520D28MC-BVNT2x
S-8520E28MC-BJNT2x
S-8520D29MC-BVOT2x
−
S-8520D30MC-BVPT2x
S-8520E30MC-BJPT2x
S-8520D31MC-BVQT2x
−
S-8520D32MC-BVRT2x
−
S-8520D33MC-BVST2x
S-8520E33MC-BJST2x
S-8520D34MC-BVTT2x
−
S-8520D35MC-BVUT2x
−
S-8520D36MC-BVVT2x
−
−
−
−
−
S-8520D50MC-BWJT2x
S-8520E50MC-BKJT2x
S-8520E52MC-BKLT2x
−
−
−
−
−
S-8520CxxMC Series
−
−
−
−
−
S-8520C25MC-BRKT2x
−
S-8520C27MC-BRMT2x
S-8520C28MC-BRNT2x
S-8520C29MC-BROT2x
S-8520C30MC-BRPT2x
S-8520C31MC-BRQT2x
S-8520C32MC-BRRT2x
S-8520C33MC-BRST2x
S-8520C34MC-BRTT2x
S-8520C35MC-BRUT2x
S-8520C36MC-BRVT2x
−
−
S-8520C50MC-BSJT2x
−
Output voltage [V]
1.5
1.6
1.8
2.0
2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
3.5
3.6
4.0
4.5
5.0
5.2
5.5
6.0
S-8520FxxMC Series
S-8520F15MC-BNAT2x
−
S-8520F18MC-BNDT2x
S-8520F20MC-BNFT2x
S-8520F25MC-BNKT2x
S-8520F26MC-BNLT2x
S-8520F27MC-BNMT2x
S-8520F28MC-BNNT2x
−
S-8520F30MC-BNPT2x
S-8520F31MC-BNQT2x
−
S-8520F33MC-BNST2x
S-8520F34MC-BNTT2x
S-8520F35MC-BNUT2x
S-8520F36MC-BNVT2x
S-8520F40MC-BNZT2x
S-8520F45MC-BOET2x
S-8520F50MC-BOJT2x
−
S-8520F55MC-BOOT2x
S-8520F60MC-BOTT2x
Remark 1.
Please contact our sales office for products with 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.
Seiko Instruments Inc.
5
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