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Rev.7.4_10
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers
S-8520/8521 Series
The S-8520/8521 Series consists of CMOS step-down switching regulatorcontrollers with PWM-control (S-8520) and PWM/PFM-switched control (S8521). These devices contain a reference voltage source, oscillation circuit, error amplifier, and other components. The S-8520 Series provides low-ripple power, high-efficiency, and excellent transient characteristics thanks to a PWM control circuit capable of varying the duty ratio linearly from 0 % up to 100 %. The series also contains an error amplifier circuit as well as a soft-start circuit that prevents overshoot at startup. The S-8521 Series works with either PWM control or PFM control, and can switch from one to the other. 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 %. This series ensures high efficiency over a wide range of conditions, from standby mode to operation of peripheral equipment.
With the addition of an external Pch Power MOS FET or PNP transistor, a coil, capacitors, and a diode connected externally, these ICs can function as step-down switching regulators. They serve as ideal power supply units for portable devices when coupled with the SOT-23-5 minipackage, providing such outstanding features as low current consumption. Since this series can accommodate an input voltage of up to 16 V, it is also ideal when operating via an AC adapter.
Features:
Applications:
* On-board power supplies of battery devices for * Low current consumption: portable telephones, electronic notebooks, PDAs, In operation: 60 A max. (A & B Series) and the like. 21 A max. (C & D Series) * Power supplies for audio equipment, including 100 A max. (E & F Series) portable CD players and headphone stereo When powered off: 0.5 A max. equipment. * Input voltage: * Fixed voltage power supply for cameras, video 2.5 V to 16 V (B, D, F Series) equipment and communications equipment. 2.5 V to 10 V (A, C, E Series) * Power supplies for microcomputers. * Output voltage: * Conversion from four NiH or NiCd cells or two Selectable between 1.5 V and lithium-ion cells to 3.3 V/3 V. 6.0 V in 0.1 V step * Conversion of AC adapter input to 5 V/3 V. * Duty ratio: 0 % to 100 % PWM control (S-8520) 25 % to 100 % PWM/PFM-switched control (S-8521) * The only peripheral components that can be used with this IC are a Pch power MOS FET or PNP transistor, a coil, a diode, and capacitors (If a PNP transistor is used, a base resistance and a capacitor will also be required). * Oscillation frequency: 180 kHz typ. (A & B Series), 60 kHz typ. (C & D Series), or 300 kHz typ. (E, F Series). * Soft-start function: 8 ms. typ. (A & B Series) 12 ms. typ.(C & D Series), or 4.5 ms. typ. (E, F Series). * With a power-off function. * With a built-in overload protection circuit. Overload detection time: 4 ms. typ. (A Series), 14 ms. typ. (C Series) or 2.6 ms. typ.(E Series).
Seiko Instruments Inc.
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10 Block Diagram:
Tr VIN
Oscillation Circuit
L
Reference Voltage Source with Soft Start
VOUT
EXT VIN CIN SD
PWM or PWM/PFMSwitched Control Circuit
+ COUT
VON / OFF ON / OFF
VSS
Note: The diode inside the IC is a parasitic diode.
Figure 1 Block Diagram
Selection Guide:
1. Product Name
S - 852 X X XX MC - XXX T2
. Tape specifications Product name abbreviation. Package name abbreviation. Output voltage x 10 Product type: A: Oscillation frequency of 180 kHz, with overload protection circuit.
B: Oscillati frequency of 180 kHz, without overload protection circuit. on C: Oscillation frequency of 60 kHz, with overload protection circuit. D: Oscillation frequency of 60 kHz, without overload protection circuit. E: Oscillation frequency of 300 kHz, with overload protection circuit. F: Oscillation frequency of 300 kHz, without overload protection circuit.
Control system
0: PWM control 1: PWM/PFM-switched control
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
2. Product List (As of September 1, 2000) A & B Series (Oscillation Frequency of 180 kHz)
Item Output Voltage (V) 1.6 1.8 1.9 2.0 2.1 2.5 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 5.0 S-8520AXXMC Series S-8520A21MC-AVG-T2 S-8520A25MC-AVK-T2 S-8520A27MC-AVM-T2 S-8520A28MC-AVN-T2 S-8520A29MC-AVO-T2 S-8520A30MC-AVP-T2 S-8520A31MC-AVQ-T2 S-8520A32MC-AVR-T2 S-8520A33MC-AVS-T2 S-8520A34MC-AVT-T2 S-8520A35MC-AVU-T2 S-8520A36MC-AVV-T2 S-8520A50MC-AWJ-T2 S-8521AXXMC Series S-8521A25MC-AXK-T2 S-8521A27MC-AXM-T2 S-8521A28MC-AXN-T2 S-8521A29MC-AXO-T2 S-8521A30MC-AXP-T2 S-8521A31MC-AXQ-T2 S-8521A32MC-AXR-T2 S-8521A33MC-AXS-T2 S-8521A34MC-AXT-T2 S-8521A35MC-AXU-T2 S-8521A36MC-AXV-T2 S-8521A50MC-AYJ-T2 S-8520BXXMC Series S-8521BXXMC Series
S-8520B18MC-ARD-T2 S-8521B18MC-ATD-T2 S-8521B19MC-ATE-T2 S-8521B20MC-ATF-T2 S-8521B21MC-ATG-T2 S-8520B25MC-ARK-T2 S-8521B25MC-ATK-T2 S-8520B27MC-ARM-T2 S-8521B27MC-ATM-T2 S-8520B28MC-ARN-T2 S-8521B28MC-ATN-T2 S-8520B29MC-ARO-T2 S-8521B29MC-ATO-T2 S-8520B30MC-ARP-T2 S-8521B30MC-ATP-T2 S-8520B31MC-ARQ-T2 S-8521B31MC-ATQ-T2 S-8520B32MC-ARR-T2 S-8521B32MC-ATR-T2 S-8520B33MC-ARS-T2 S-8521B33MC-ATS-T2 S-8520B34MC-ART-T2 S-8521B34MC-ATT-T2 S-8520B35MC-ARU-T2 S-8521B35MC-ATU-T2 S-8520B36MC-ARV-T2 S-8521B36MC-ATV-T2 S-8520B50MC-ASJ-T2 S-8521B50MC-AUJ-T2
C & D Series (Oscillation Frequency of 60 kHz)
Item Output Voltage (V) 1.6 2.0 2.5 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 5.0 S-8520CXXMC Series S-8520C25MC-BRK-T2 S-8520C27MC-BRM-T2 S-8520C28MC-BRN-T2 S-8520C29MC-BRO-T2 S-8520C30MC-BRP-T2 S-8520C31MC-BRQ-T2 S-8520C32MC-BRR-T2 S-8520C33MC-BRS-T2 S-8520C34MC-BRT-T2 S-8520C35MC-BRU-T2 S-8520C36MC-BRV-T2 S-8520C50MC-BSJ-T2 S-8521CXXMC Series S-8521C16MC-BTB-T2 S-8521C25MC-BTK-T2 S-8521C27MC-BTM-T2 S-8521C28MC-BTN-T2 S-8521C29MC-BTO-T2 S-8521C30MC-BTP-T2 S-8521C31MC-BTQ-T2 S-8521C32MC-BTR-T2 S-8521C33MC-BTS-T2 S-8521C34MC-BTT-T2 S-8521C35MC-BTU-T2 S-8521C36MC-BTV-T2 S-8521C50MC-BUJ-T2 S-8520DXXMC Series S-8520D25MC-BVK-T2 S-8520D27MC-BVM-T2 S-8520D28MC-BVN-T2 S-8520D29MC-BVO-T2 S-8520D30MC-BVP-T2 S-8520D31MC-BVQ-T2 S-8520D32MC-BVR-T2 S-8520D33MC-BVS-T2 S-8520D34MC-BVT-T2 S-8520D35MC-BVU-T2 S-8520D36MC-BVV-T2 S-8520D50MC-BWJ-T2 S-8521DXXMC Series S-8521D16MC-BXB-T2 S-8521D20MC-BXF-T2 S-8521D25MC-BXK-T2 S-8521D27MC-BXM-T2 S-8521D28MC-BXN-T2 S-8521D29MC-BXO-T2 S-8521D30MC-BXP-T2 S-8521D31MC-BXQ-T2 S-8521D32MC-BXR-T2 S-8521D33MC-BXS-T2 S-8521D34MC-BXT-T2 S-8521D35MC-BXU-T2 S-8521D36MC-BXV-T2 S-8521D50MC-BYJ-T2
E & F Series (Oscillation Frequency of 300 kHz)
Item Output Voltage (V) 1.5 1.8 2.0 2.5 2.7 3.0 3.3 3.4 3.5 5.0 S-8520EXXMC Series S-8520E18MC-BJD-T2 S-8520E25MC-BJK-T2 S-8520E30MC-BJP-T2 S-8520E33MC-BJS-T2 S-8520E50MC-BKJ-T2 S-8521EXXMC Series S-8521E15MC-BLA-T2 S-8521E18MC-BLD-T2 S-8521E20MC-BLF-T2 S-8521E30MC-BLP-T2 S-8521E33MC-BLS-T2 S-8521E35MC-BLU-T2 S-8521E50MC-BMJ-T2 S-8520FXXMC Series S-8520F18MC-BND-T2 S-8520F25MC-BNK-T2 S-8520F27MC-BNM-T2 S-8520F30MC-BNP-T2 S-8520F33MC-BNS-T2 S-8520F34MC-BNT-T2 S-8520F50MC-BOJ-T2 S-8521FXXMC Series S-8521F18MC-BPD-T2 S-8521F30MC-BPP-T2 S-8521F33MC-BPS-T2 S-8521F50MC-BQJ-T2
For the availability of product samples listed above, contact the SII Sales Department.
Seiko Instruments Inc.
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10 Pin Assignment:
SOT-23-5 Top view 5 4
Pin No. 1 2 3 4 5
Pin Name Power-off pin
Function
L: Step-down operation stopped (All circuits deactivated)
ON/OFF H: Normal operation (Step-down operation) VSS VOUT EXT VIN GND pin Output voltage monitoring pin
Connection pin for external transistor
IC power supply pin
1
2
3
Figure 2
Absolute Maximum Ratings:
(Ta = 25 C unless otherwise specified) Item VIN pin voltage VOUT pin voltage ON/OFF pin voltage EXT pin voltage EXT pin current Power dissipation Operating temperature range Storage temperature range Symbol *1 VIN VOUT *1 VON/OFF VEXT IEXT PD TOPR TSTG Ratings VSS -0.3 to VSS+12 or VSS+18 VSS -0.3 to VSS+12 or VSS+18 VSS -0.3 to VSS+12 or VSS+18 VSS -0.3 to VIN+0.3 50 250 -40 to +85 -40 to +125 Unit V V V V mA mW C C
*1. VSS+12 V for S-8520/21A/C/E; VSS+18 V for S-8520/21B/D/F
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.
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series Electrical Characteristics:
1. S-8520/21 A & B Series
Parameter Output voltage *1 Input voltage Symbol VOUT(E) VIN Conditions - S-8520/21A Series S-8520/21B Series Current consumption 1 Current consumption during power off ISS1 ISSS VOUT = VOUT(S) x 1.2 VON/OFF = 0 V S-8520/21X15 - 24 S-8520/21X25 - 34 IEXTH VEXT =VIN-0.4 V S-8520/21X35 - 44 S-8520/21X45 - 54 EXT pin output current S-8520/21X55 - 60 S-8520/21X15 - 24 S-8520/21X25 - 34 IEXTL VEXT = 0.4 V S-8520/21X35 - 44 S-8520/21X45 - 54 S-8520/21X55 - 60 Line regulation Load regulation Output voltage temperature coefficient Oscillation frequency VOUT1 VOUT2 VOUT /Ta fosc VIN = VOUT(S) x1.2 to x1.4 Load current =10A to IOUT(See below) x1.25 Ta= - 40 C to 85 C Measure waveform VOUT(S) 2.5 V at EXT pin VOUT(S) 2.4 V Measure waveform at EXT pin under no load. Evaluate oscillation at EXT pin Evaluate oscillation stop at EXT pin - - - Duration from the time VOUT is reduced to 0 V to the time the EXT pin obtains VIN. -
*4
Min.
(Ta =25 C, unless otherwise specified)
Typ. Max. Units V V VOUT(S) x1.024 10.0 16.0 60 0.5 - - - - - - - - - - 60 60 - 207 216 40 - 0.3 0.1 0.1 16.0 8.0 - % V A A ms ms % 3 2 1 1 3 2 3 mV mV V/C kHz 3 3 3 3 mA - A A 2 2
VOUT(S) VOUT(S) x 0.976 2.5 - 2.5 - - -2.3 -3.7 -5.3 -6.7 -8.0 +4.3 +7.0 +9.9 +12.6 +15.0 - - - 153 144 15 1.8 - -0.1 -0.1 4.0 2.0 - - 35 - -4.5 -7.0 -9.3 -11.3 -13.3 +8.4 +13.2 +17.5 +21.4 +25.1 30 30 VOUT(S) x 5E-5 180 180 25 - - - - 8.0 4.0 93
Measurement Circuit 3 2
PWM/PFM-control switch PFM Duty *2 duty ratio Power-Off pin VSH input voltage VSL Power-Off pin ISH input leakage current ISL Soft-Start time TSS TPRO Overload detection time *3 Efficiency EFFI
Conditions: The recommended components are connected to the IC, unless otherwise indicated. VIN = VOUT(S) x 1.2 [V], IOUT = 120 [mA] (VIN= 2.5 V, if VOUT(S) 2.0 V.) Peripheral components: Coil : Sumida Electric Co., Ltd. CD54 (47 H). Diode : Matsushita Electronics Corporation MA720 (Schottky type). Capacitor : Matsushita Electronics Corporation TE (16 V, 22 F tantalum type). Transistor : Toshiba Corporation 2SA1213Y. Base resistance (Rb) : 0.68 k Base capacitor (Cb) : 2200 pF (Ceramic type) The power-off pin is connected to VIN. Notes: The output voltage indicated above represents a typical output voltage set up. These specifications apply in common to both S-8520 and S-8521, unless otherwise noted. *1. VOUT(S) Specified output voltage value. VOUT(E) Actual output voltage value. *2. Applicable to the S-8521A Series and S-8521B Series. *3. Applicable to the S-8520A Series and S-8521A Series. *4. VIN = 2.5 V to 2.94 V, if VOUT(S) 2.0 V.
Seiko Instruments Inc.
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
2. S-8520/21 C & D Series
Parameter Output voltage *1 Input voltage Symbol VOUT(E) VIN Conditions - S-8520/21C Series S-8520/21D Series Current consumption 1 Current consumption during power-off ISS1 ISSS VOUT = VOUT(S) x 1.2 VON/OFF = 0 V S-8520/21X15 - 24 S-8520/21X25 - 34 IEXTH VEXT = VIN-0.4 V S-8520/21X35 - 44 S-8520/21X45 - 54 EXT pin output current S-8520/21X55 - 60 S-8520/21X15 - 24 S-8520/21X25 - 34 IEXTL VEXT = 0.4 V S-8520/21X35 - 44 S-8520/21X45 - 54 S-8520/21X55 - 60 Line regulation Load regulation Output voltage temperature coefficient Oscillation frequency VOUT1 VIN = VOUT(S) x1.2 to x1.4 VOUT2 Load current =10 A to IOUT(See below) x1.25 VOUT Ta = - 40 C to 85 C /Ta fosc Measure waveform VOUT(S) 2.5 V at EXT pin VOUT(S) 2.4 V PFM Duty VSH VSL ISH ISL TSS TPRO EFFI Measure waveform at EXT pin under no load. Evaluate oscillation at EXT pin Evaluate oscillation stop at EXT pin - - - Duration from the time VOUT is reduced to 0 V to the time the EXT pin obtains VIN. -
*4
Min. VOUT(S) x 0.976 2.5 2.5 - - -2.3 -3.7 -5.3 -6.7 -8.0 +4.3 +7.0 +9.9 +12.6 +15.0 - - - 48 45 15 1.8 - -0.1 -0.1 6.0 7.0 -
(Ta = 25 C unless otherwise specified)
Typ. Max. Units V V VOUT(S) - - 10 - -4.5 -7.0 -9.3 -11.3 -13.3 +8.4 +13.2 +17.5 +21.4 +25.1 30 30 VOUT(S) x 5E-5 60 60 25 - - - - 12.0 14.0 93 VOUT(S) x 1.024 10.0 16.0 21 0.5 - - - - - - - - - - 60 60 - 72 75 40 - 0.3 0.1 0.1 24.0 28.0 - % V A A ms ms % 3 2 1 1 3 2 3 mV mV V/C kHz 3 3 3 3 mA - A A 2 2 Measuremen t Circuit 3 2
PWM/PFM-control switch duty ratio *2 Power-Off pin input voltage Power-Off pin input leakage current Soft-Start time Overload detection time *3 Efficiency
Conditions: The recommended components are connected to the IC, unless otherwise indicated. VIN = VOUT x 1.2 [V], IOUT = 120 [mA] (VIN= 2.5 V, if VOUT(S) 2.0 V.) Peripheral components: Coil : Sumida Electric Co., Ltd. CD54 (47 H). Diode : Matsushita Electronics Corporation MA720 (Schottky type). Capacitor : Matsushita Electronics Corporation TE (16 V, 22 F tantalum type). Transistor : Toshiba Corporation 2SA1213Y. Base resistance (Rb) : 0.68 k Base capacitor (Cb) : 2200 pF (Ceramic type) The power-off pin is connected to VIN. Notes: The output voltage indicated above represents a typical output voltage set up. These specifications apply in common to both S-8520 and S-8521, unless otherwise noted. *1. VOUT(S) Specified output voltage value. VOUT(E) Actual output voltage value. *2. Applicable to the S-8521C Series and S-8521D Series. *3. Applicable to the S-8520C Series and S-8521C Series. *4. VIN = 2.5 V to 2.94 V, if VOUT(S) 2.0 V.
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
3. S-8520/21 E & F Series
Parameter Output voltage *1 Input voltage Symbol VOUT(E) VIN Conditions - S-8520/21E Series S-8520/21F Series Current consumption 1 Current consumption during power-off ISS1 ISSS VOUT = VOUT(S) x 1.2 VON/OFF = 0 V S-8520/21X15 - 24 S-8520/21X25 - 34 IEXTH VEXT = VIN-0.4 V S-8520/21X35 - 44 S-8520/21X45 - 54 EXT pin output current S-8520/21X55 - 60 S-8520/21X15 - 24 S-8520/21X25 - 34 IEXTL VEXT = 0.4 V S-8520/21X35 - 44 S-8520/21X45 - 54 S-8520/21X55 - 60 Line regulation Load regulation Output voltage temperature coefficient Oscillation frequency VOUT1 VIN = VOUT(S) x1.2 to x1.4 VOUT2 Load current =10 A to IOUT(See below) x1.25 VOUT Ta = -40 C to 85 C /Ta fosc Measure waveform VOUT 2.5 V at EXT pin VOUT 2.4 V Measure waveform at EXT pin under no load. Evaluate oscillation at EXT pin Evaluate oscillation stop at EXT pin - - - Duration from the time VOUT is reduced to 0 V to the time the EXT pin obtains VIN. -
*4
Min.
(Ta = 25 C unless otherwise specified)
Typ. Max. Units V V Measurement Circuit 3 2 2 2
VOUT(S) VOUT(S) VOUT(S) x0.976 x 1.024 2.5 10.0 - 2.5 - - -2.3 -3.7 -5.3 -6.7 -8.0 +4.3 +7.0 +9.9 +12.6 +15.0 - - - 240 225 15 1.8 - -0.1 -0.1 2.0 1.3 - - 60 - -4.5 -7.0 -9.3 -11.3 -13.3 +8.4 +13.2 +17.5 +21.4 +25.1 30 30 VOUT x 5E-5 300 300 25 - - - - 4.5 2.6 90 16.0 100 0.5 - - - - - - - - - - 60 60 - 360 375 40 - 0.3 0.1 0.1 9.2 4.5 -
A A
mA
-
mV mV V/C kHz
3 3 3 3
PWM/PFM-control switch PFM Duty duty ratio *2 Power-Off pin VSH input voltage VSL Power-Off pin ISH input leakage current ISL Soft-Start time TSS TPRO Overload detection time *3 Efficiency EFFI
% V A A ms ms %
3 2 1 1 3 2 3
Conditions: The recommended components are connected to the IC, unless otherwise indicated. VIN = VOUT x 1.2 [V], IOUT = 120 [mA] (VIN= 2.5 V, if VOUT(S) 2.0 V.) Peripheral components: Coil : Sumida Electric Co., Ltd. CD54 (47 H). Diode : Matsushita Electronics Corporation MA720 (Schottky type). Capacitor : Matsushita Electronics Corporation TE (16 V, 22 F tantalum type). Transistor : Toshiba Corporation 2SA1213Y. Base resistance (Rb) : 0.68 k Base capacitor (Cb) : 2200 pF (Ceramic type) The power-off pin is connected to VIN. Notes: The output voltage indicated above represents a typical output voltage set up. These specifications apply in common to both S-8520 and S-8521, unless otherwise noted. *1. VOUT(S) Specified output voltage value. VOUT(E) Actual output voltage value. *2. Applicable to the S-8521E Series and S-8521F Series. *3. Applicable to the S-8520E Series and S-8521E Series. *4. VIN = 2.5 V to 2.94 V, if VOUT(S) 2.0 V.
Seiko Instruments Inc.
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10 Measurement Circuits:
1 VIN open EXT VOUT open
2
Oscillation A
VIN
EXT
VOUT
A
ON/OFF VSS
+ -
ON/OFF
VSS
3
0.68 k VIN + - EXT
2200 pF VOUT + VSS - V
ON/OFF
Figure 3
Operation:
1. Step-Down DC-DC Converter 1.1 PWM Control (S-8520 Series) The S-8520 Series consists of DC/DC converters that employ a pulse-width modulation (PWM) system. This series is characterized by its low current consumption. In conventional PFM system DC/DC converters, pulses are skipped when they are operated with a low output load current, causing variations in the ripple frequency of the output voltage and an increase in the ripple voltage. Both of these effects constitute inherent drawbacks to those converters. In converters of the S-8520 Series, the pulse width varies in a range from 0 % to 100 %, according to the load current, and yet ripple voltage produced by the switching can easily be removed through a filter because the switching frequency remains constant. Therefore, these converters provide a low-ripple power over broad ranges of input voltage and load current. 1.2 PWM/PFM-Switched Control (S-8521 Series) The S-8521 Series consists of DC/DC converters capable of automatically switching the pulse-wide modulation system (PWM) over to the pulse-frequency modulation system (PFM), and vice versa, according to the load current. This series of converters features low current consumption. In a region of high output load currents, the S-8521 Series converters function with PWM control, where the pulse-width duty varies from 25 % to 100 %. This function helps keep the ripple power low. For certain low output load currents, the converters are switched over to PFM control, whereby pulses having their pulse-width duty fixed at 25 % are skipped depending on the quantity of the load current, and are output to a switching transistor. This causes the oscillation circuit to produce intermittent oscillation. As a result, current consumption is reduced and efficiency losses are prevented under low loads. Especially for output load currents in the region of 100 A, these DC/DC converters can operate at extremely high efficiency. 8 Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
2. Power-Off Pin (ON/OFF Pin) This pin deactivates or activates the step-down operation.When the power-off pin is set to "L", the VIN voltage appears through the EXT pin, prodding the switching transistor to go off. All the internal circuits stop working, and substantial savings in current consumption are thus achieved. The power-off pin is configured as shown in Figure 4. Since pull-up or pull-down is not performed internally, please avoid operating the pin in a floating state. Also, try to refrain from applying a voltage of 0.3 V to 1.8 V to the pin, lest the current consumption increase. When this power-off pin is not used, leave it coupled to the VIN pin. VIN Power-Off Pin "H" "L" CR Oscillation Circuit Activated Deactivated Output Voltage Set value VSS VSS Figure 4 3. Soft-Start Function The S-8520/21 Series comes with a built-in soft-start circuit. This circuit enables the output voltage to rise gradually over the specified soft-start time, when the power is switched on or when the power-off pin remains at the "H" level. This prevents the output voltage from overshooting. However, the soft-start function of this IC is not able to perfectly prevent a rush current from flowing to the load (see Figure 5). Since this rush current depends on the input voltage and load conditions, we recommend that you evaluate it by testing performance with the actual equipment.
S-8520A33MC (VIN :0 4.0 V)
3V VOUT (1 V/div) 0V
ON/OFF
Power switched on
1.5 A Rush current (0.5 A/div) 0A
t(1 ms/div)
Figure 5 Waveforms of Output Voltage and Rush Current at Soft-Start
4. Overload Protection Circuit (A, C, E Series) The S-8520/21A, S-8520/21C Series, and S-8520/21E Series come with a built-in overload protection circuit. If the output voltage falls because of an overload, the maximum duty state (100 %) will continue. If this 100% duty state lasts longer than the prescribed overload detection time (TPRO), the overload protection circuit will hold the EXT pin at "H," thereby protecting the switching transistor and inductor. When the overload protection circuit is functioning, the reference voltage circuit will be activated by means of a Seiko Instruments Inc. 9
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
soft-start in the IC, and the reference voltage will rise slowly from 0 V. The reference voltage and the feedback voltage obtained by dividing the output voltage are compared to each other. So long as the reference voltage is lower, the EXT pin will be held at "H" to keep the oscillation inactive. If the reference voltage keeps rising and exceeds the feedback voltage, the oscillation will resume. If the load is heavy when the oscillation is restarted, and the EXT pin holds the "L" level longer than the specified overload detection time (TPRO), the overload protection circuit will operate again, and the IC will enter intermittent operation mode, in which it repeats the actions described above. Once the overload state is eliminated, the IC resumes normal operation.
Waveforms at EXT pin
Overload detection time (TPRO)
Protection circuit ON (TSS x 0.3)
Figure 6 Waveforms Appearing at EXT Pin As the Overload Protection Circuit Operates 5. 100 % Duty Cycle The S-8520/21 Series operates with a maximum duty cycle of 100 %. When a B, D, F Series product not provided with an overload protection circuit is used, the switching transistor can be kept ON to supply current to the load continually, even in cases where the input voltage falls below the preset output voltage value. The output voltage delivered under these circumstances is one that results from subtracting, from the input voltage, the voltage drop caused by the DC resistance of the inductance and the on-resistance of the switching transistor. If an A, C, E Series product provided with an overload protection circuit is used, this protection circuit will function when the 100 % duty state has lasted longer than the preset overload detection time (TPRO), causing the IC to enter intermittent operation mode. Under these conditions, the IC will not be able to supply current to the load continually, unlike the case described in the preceding paragraph.
Selection of Series Products and Associated External Components
1. Method for selecting series products The S-8520/21 Series is classified into 12 types, according to the way the control systems (PWM and PWM/PFM-Switched), the different oscillation frequencies, and the inclusion or exclusion of an overload protection circuit are combined one with another. Please select the type that best suits your needs by taking advantage of the features of each type described below. Control systems: Two different control systems are available: PWM control system (S-8520 Series) and PWM/PFMswitched control system (S-8521 Series). If particular importance is attached to the operation efficiency while the load is on standby -- for example, in an application where the load current heavily varies from that in standby state as the load starts operating -- a high efficiency will be obtained in standby mode by selecting the PWM/PFMswitched control system (S-8521 Series). Moreover, for applications where switching noise poses a serious problem, the PWM control system (S-8520 Series), in which the switching frequency does not vary with the load current, is preferable because it can eliminate ripple voltages easily using a filter. Oscillation frequencies: Three oscillation frequencies--180 kHz (A & B Series) and 60 kHz (C & D Series), 300 kHz (E, F Series)--are available. Because of their high oscillation frequency and low-ripple voltage the A, B, E, F Series offer excellent transient response characteristics. The products in these series allow the use of small-sized inductors since the peak current remains smaller in the same load current than with products of the other series. In addition, they can also be used with small output capacitors. These outstanding features 10 Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
make the A & B Series ideal products for downsizing the associated equipment. On the other hand, the C & D Series, having a lower oscillation frequency, are characterized by a small self-consumption of current and excellent efficiency under light loads. In particular, the D Series, which employs a PWM/PFM-switched control system, enables the operation efficiency to be improved drastically when the output load current is approximately 100 A. (See Reference Data.) Overload protection circuit: Products can be chosen either with an overload protection circuit (A, C, E Series) or without one (B, D, F Series). Products with an overload protection circuit (A, C, E Series) enter intermittent operation mode when the overload protection circuit operates to accommodate overloads or load short-circuiting. This protects the switching elements and inductors. Nonetheless, in an application where the load needs to be fed continually with a current by taking advantage of the 100 % duty cycle state, even if the input voltage falls below the output voltage value, a B, D, F Series product will have to be used. Choose whichever product best handles the conditions of your application. In making the selection, please keep in mind that the upper limit of the operating voltage range is either 10 V (A, C, E Series) or 16 V (B, D, F Series), depending on whether the product comes with an overload protection circuit built in. The table below provides a rough guide for selecting a product type depending on the requirements of the application. Choose the product that gives you the largest number of circles (O). A
An overload protection circuit is required The input voltage range exceeds 10 V The efficiency under light loads(load current 1 mA) is an important factor To be operated with a medium load current (200 mA class) To be operated with a high load current (1 A class) It is important to have a low-ripple voltage Importance is attached to the downsizing of external components
B
S-8520 C D
E
F
A
B
S-8521 C D
E
F
The symbol " " denotes an indispensable condition, while the symbol " " indicates that the corresponding series has superiority in that aspect. The symbol " " indicates particularly high superiority.
2. Inductor The inductance value greatly affects the maximum output current IOUT and the efficiency . As the L-value is reduced gradually, the peak current Ipk increases, to finally reach the maximum output current IOUT when the L-value has fallen to a certain point. If the L-value is made even smaller, IOUT will begin decreasing because the current drive capacity of the switching transistor becomes insufficient. Conversely, as the L-value is augmented, the loss due to Ipk in the switching transistor will decrease until the efficiency is maximized at a certain L-value. If the L-value is made even larger, the loss due to the series resistance of the coil will increase to the detriment of the efficiency. If the L-value is increased in an S-8520/21 Series product, the output voltage may turn unstable in some cases, depending on the conditions of the input voltage, output voltage, and the load current. Perform thorough evaluations under the conditions of actual service and decide on an optimum L-value. In many applications, selecting a value of A/B/C/D Series 47H, E, F Series 22 H will allow a S-8520/21 Series product to yield its best characteristics in a well balanced manner. When choosing an inductor, pay attention to its allowable current, since a current applied in excess of the allowable value will cause the inductor to produce magnetic saturation, leading to a marked decline in efficiency. Seiko Instruments Inc. 11
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
Therefore, select an inductor in which the peak current Ipk will not surpass its allowable current at any moment. The peak current Ipk is represented by the following equation in continuous operation mode: IPK = IOUT + (VOUT + VF) x (VIN - VOUT) 2 x fosc x L x (VIN + VF)
Where fosc is the oscillation frequency, L the inductance value of the coil, and VF the forward voltage of the diode. 3. Diode The diode to be externally coupled to the IC should be a type that meets the following conditions: Its forward voltage is low (Schottky barrier diode recommended). Its switching speed is high (50 ns max.). Its reverse direction voltage is higher than VIN. Its current rating is higher than Ipk. 4. Capacitors (CIN, COUT) The capacitor inserted on the input side (CIN) serves to lower the power impedance and to average the input current for better efficiency. Select the CIN-value according to the impedance of the power supplied. As a rough rule of thumb, you should use a value of 47F to 100 F, although the actual value will depend on the impedance of the power in use and the load current value. For the output side capacitor (COUT), select one of large capacitance with low ESR (Equivalent Series Resistance) for smoothing the ripple voltage. However, notice that a capacitor with extremely low ESR (say, below 0.3 ), such as a ceramic capacitor, could make the output voltage unstable, depending on the input voltage and load current conditions. Instead, a tantalum electrolytic capacitor is recommended. A capacitance value from 47F to 100 F can serve as a rough yardstick for this selection. 5. External Switching Transistor The S-8520/21 Series can be operated with an external switching transistor of the enhancement (Pch) MOS FET type or bipolar (PNP) typ. 5.1 Enhancement MOS FET type The EXT pin of the S-8520/21 Series is capable of directly driving a Pch power MOS FET with a gate capacity of some 1000 pF. When a Pch power MOS FET is chosen, because it has a higher switching speed than a PNP type bipolar transistor and because power losses due to the presence of a base current are avoided, efficiency will be 2 % to 3 % higher than when other types of transistor are employed. The important parameters to be kept in mind in selecting a Pch power MOS FET include the threshold voltage, breakdown voltage between gate and source, breakdown voltage between drain and source, total gate capacity, on-resistance, and the current rating. The EXT pin swings from voltage VIN over to voltage VSS. If the input voltage is low, a MOS FET with a low threshold voltage has to be used so that the MOS FET will come on as required. If, conversely, the input voltage is high, select a MOS FET whose gate-source breakdown voltage is higher than the input voltage by at least several volts. Immediately after the power is turned on, or when the power is turned off (that is, when the step-down operation is terminated), the input voltage will be imposed across the drain and the source of the MOS FET. Therefore, the transistor needs to have a drain-source breakdown voltage that is also several volts higher than the input voltage. The total gate capacity and the on-resistance affect the efficiency. The power loss for charging and discharging the gate capacity by switching operation will increase, when the total gate capacity becomes larger and the input voltage rises higher. Therefore the gate capacity affects the efficiency of power in a low load current region. If the efficiency under light loads is a matter of particular concern, select a MOS FET with a small total gate capacity. In regions where the load current is high, the efficiency is affected by power losses caused due to the onresistance of the MOS FET. Therefore, if the efficiency under heavy loads is particularly important for 12 Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
your application, choose a MOS FET with as low an on-resistance as possible. As for the current rating, select a MOS FET whose maximum continuous drain current rating is higher than the peak current Ipk. For reference purpose, some efficiency data has been included in this document. For applications with an input voltage range of 10 V or less, data was obtained by using TM6201 of Toyoda Automatic Loom Works, Ltd. IRF7606, a standard of International Rectifier, was used for applications with an input voltage range over 10 V. Refer to "Reference Data." 5.2 Bipolar PNP type Figure 7 shows a sample circuit diagram using Toshiba 2SA1213-Y for the bipolar transistor (PNP). The driving capacity for increasing the output current by means of a bipolar transistor is determined by the hFE-value and the Rb-value of that bipolar transistor.
2SA1213-Y VIN
Rb
Cb EXT
VIN
Figure 7 The Rb-value is given by the following equation: Rb= VIN-0.7 Ib - 0.4 |IEXTL|
Find the necessary base current Ib using the hFE - value of bipolar transistor by the equation, Ib = Ipk/hFE, and select a smaller Rb-value. A small Rb-value will certainly contribute to increasing the output current, but it will also adversely affect the efficiency. Moreover, in practice, a current may flow as the pulses or a voltage drop may take place due to the wiring resistance or some other reason. Determine an optimum value through experimentation. In addition, if speed-up capacitor Cb is inserted in parallel with resistance Rb, as shown in Figure 7, the switching loss will be reduced, leading to a higher efficiency. Select a Cb-value by using the following equation as a guide: Cb 1 2 xRb x f OSC x 0.7
However, the practically-reasonable Cb value differs depending upon the characteristics of the bipolar transistor. Optimize the Cb value based on the experiment result.
Seiko Instruments Inc.
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10 Standard Circuits:
(1) Using a bipolar transistor:
Tr VIN Rb Cb EXT VIN CIN SD
PWM or PWM/PFMSwitched Control Circuit Oscillation Circuit
L
Reference Voltage Source with Soft-Start
VOUT
+ - COUT
ON / OFF VSS
VON / OFF
Figure 8 (2) Using a Pch MOS-FET transistor
Tr VIN
Oscillation Circuit
L
Reference Voltage Source with Soft-Start
VOUT
EXT VIN SD CIN
PWM or PWM/PFMSwitched Control Circuit
+ - COUT
ON / OFF VSS
VON / OFF
Figure 9
Precautions:
Install the external capacitors, diode, coil, and other peripheral components as close to the IC as possible, and secure grounding at a single location. Any switching regulator intrinsically produces a ripple voltage and spike noise, which are largely dictated by the coil and capacitors in use. When designing a circuit, first test them on actual equipment. The overload protection circuit of this IC performs the protective function by detecting the maximum duty time (100 %). In choosing the components, make sure that overcurrents generated by short-circuits in the load, etc., will not surpass the allowable dissipation of the switching transistor and inductor. Make sure that dissipation of the switching transistor will not surpass the allowable dissipation of the package. (especially at the time of high temperature)
Power dissipation
200
100 0 0 50 100 150
Temperature Ta (0C)
PD (mW)
Figure 10 Power dissipation of an SOT-23-5 Package (Free-Air) 14 Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
Do not apply an electrostatic discharge to this IC that exceeds the performance ratings of the built-in electrostatic protection circuit. Seiko Instruments Inc. shall not be responsible for any patent infringement by products including the S8520/8521 Series in connection with the method of using the S-8520/8521 Series in such products, the product specifications or the country of destination thereof.
Application Circuits:
1. External adjustment of output voltage The S-8520/21 Series allows you to adjust the output voltage or to set the output voltage to a value over the preset output voltage range (6 V) of the products of this series, when external resistances RA, RB, and capacitor CC are added, as illustrated in Figure 11. Moreover, a temperature gradient can be obtained by inserting a thermistor or other element in series with RA and RB.
OUT CC RA
EXT VIN
S-8520/21 Series VOUT
PWM or PWM/PFMSwitched Control Circuit Oscillation Cirucuit
+ -
ON/OFF
+ --
R1
D1
R2
RB
+ -
Reference Voltage Source with Soft-Start
VSS
Figure 11 The S-8520 and 21 Series have an internal impedance of R1 and R2 between the VOUT and the VSS pin, as shown in Figure 11. Therefore, the output voltage (OUT) is determined by the output voltage value VOUT of the S-8520/21 Series, and the ratio of the parallel resistance value of external resistance RB and internal resistances R1 + R2 of the IC, to external resistance RA. The output voltage is expressed by the following equation: OUT = VOUT + VOUT x RA / ( RB // ( R1 + R2 )) (Note: // denotes a combined resistance in parallel.) The voltage accuracy of the output OUT set by resistances RA and RB is not only affected by the IC's output voltage accuracy (VOUT 2.4 %), but also by the absolute precision of external resistances RA and RB in use and the absolute value deviations of internal resistances R1 and R2 in the IC. Let us designate the maximum deviations of the absolute value of external resistances RA and RB by RAmax and RBmax, respectively, the minimum deviations by RAmin and RBmin, respectively, and the maximum and minimum deviations of the absolute value of internal resistances R1 and R2 in the IC by (R1+R2)max and (R1+R2) min, respectively. Then, the minimum deviation value OUTmin and the maximum deviation value OUTmax of the output voltage OUT are expressed by the following equations: OUTmin = VOUT x 0.976 + VOUT x 0.976 x RAmin / ( RBmax // ( R1 + R2 )max ) OUTmax = VOUT x 1.024 + VOUT x 1.024 x RAmax / ( RBmin // ( R1 + R2 )min ) The voltage accuracy of the output OUT cannot be made higher than the output voltage accuracy (VOUT 2.4 %) of the IC itself, without adjusting the external resistances RA and RB involved. The closer the voltage value of the output OUT and the output voltage value (VOUT) of the IC are brought to one other, the more the output voltage remains immune to deviations in the absolute accuracy of externally connected resistances RA and RB and the absolute value of internal resistances R1 and R2 in the IC. In particular, to suppress the influence of deviations in internal resistances R1 and R2 in the IC, a major contributor to deviations in the output OUT, the external resistances RA and RB must be limited to a much smaller value than that of internal resistances R1 and R2 in the IC. Seiko Instruments Inc. 15
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
On the other hand, a reactive current flows through external resistances RA and RB. This reactive current must be reduced to a negligible value with respect to the load current in the actual use of the IC so that the efficiency characteristics will not be degraded. This requires that the value of external resistance RA and RB be made sufficiently large. However, too large a value (more than 1 M) for the external resistances RA and RB would make the IC vulnerable to external noise. Check the influence of this value on actual equipment. There is a tradeoff between the voltage accuracy of the output OUT and the reactive current. This should be taken into consideration based on the requirements of the intended application. Deviations in the absolute value of internal resistances R1 and R2 in the IC vary with the output voltage of the S-8520/21 Series, and are broadly classified as follows: Output voltage 1.5 V to 2.0 V 5.16 M to 28.9 M Output voltage 2.1 V to 2.5 V 4.44 M to 27.0 M Output voltage 2.6 V to 3.3 V 3.60 M to 23.3 M Output voltage 3.4 V to 4.9 V 2.44 M to 19.5 M Output voltage 5.0 V to 6.0 V 2.45 M to 15.6 M When a value of R1+R2 given by the equation indicated below is taken in calculating the voltage value of the output OUT, a median voltage deviation will be obtained for the output OUT. R1 + R2 = 2 / (1 / maximum deviation in absolute value of internal resistances R1 and R2 in IC + 1 / minimum deviation in absolute value of internal resistances R1 and R2 of IC) Moreover, add a capacitor CC in parallel to the external resistance RA in order to avoid output oscillations and other types of instability (See Figure 11). Make sure that CC is larger than the value given by the following equation: CC (F) 1 / (2 x x RA () x 7.5 kHz) If a large CC-value is selected, a longer soft-start time than the one set up in the IC will be set. SII is equipped with a tool that allows you to automatically calculate the necessary resistance values of RA and RB from the required voltage accuracy of the output OUT. SII will be pleased to assist its customers in determining the RA and RB values. Should such assistance be desired, please inquire. Moreover, SII also has ample information on which peripheral components are suitable for use with this IC and data concerning the deviations in the IC's characteristics. We are ready to help our customers with the design of application circuits. Please contact the SII Components Sales Dept.
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series Characteristics of Major Parameters (Typical values):
(1)
ISS1-VIN S-8520/21(Fosc:60 kHz) 20 15 ISS1 10 (A) 5 0 2 4 6 8 10 12 14 16 VIN(V) Ta=25 Ta=85 Ta=-40
(2)
ISS1-VIN S-8520/21(Fosc:180 kHz) 40 30 ISS1 20 (A) 10 0 2 4 6 8 10 12 14 16 VIN(V)
Ta=25 Ta=85 Ta=-40
(3)
ISS1-VIN S-8520/21(Fosc:300 kHz) 60 50 40 ISS1 30 (A) 20 10 0 2 4 6 8 10 12 14 16 VIN(V) Ta=85
(4)
Fosc-VIN S-8520/21(Fosc:60 kHz) 80 75 70 65 Fosc (kHz) 60 55 50 45 40 2 4 6 8 10 12 14 16 VIN(V) Ta=25 Ta=85
Ta=25
Ta=-40
Ta=-40
(5)
Fosc-VIN S-8520/21(Fosc:180 kHz) 220 210 200 190 Fosc (kHz) 180 170 160 150 140 2 4 6 8 10 VIN(V) Ta=25
(6)
Fosc-VIN S-8520/21(Fosc:300 kHz) 360 340 320 Fosc 300 (kHz) 280 Ta=85 Ta=-40 12 14 16 260 240 2 4 6 8 10 12 14 16 VIN(V)
Ta=25 Ta=-40 Ta=85
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
(7)
IEXTH-VIN S-8520/21 -60 -50 -40 IEXTH (mA) -30 -20 -10 0 2 4 6 8 VIN(V) 10 12 14 16 Ta=85 Ta=-40 Ta=25
(8)
IEXTL-VIN S-8520/21 60 50 40 IEXTL 30 (mA) 20 10 0 2 4 6 8 10 12 14 16 VIN(V) Ta=-40 Ta=25 Ta=85
(9)
TSS-VIN S-8520/21(Fosc:60 kHz) 25 20 TSS (ms) 15 10 5 0 2 4 6 8 VIN(V) 10 12 14 16 Ta=85 Ta=-40 Ta=25
(10)
TSS-VIN S-8520/21(Fosc:180 kHz) 25 20 TSS (ms) 15 10 5 0 2 4 6 8 10 12 14 16 VIN(V) Ta=85 Ta=-40 Ta=25
(11)
TSS-VIN S-8520/21(Fosc:300 kHz) 10 8 TSS (ms) 6 4 2 0 2 4 6 8 10 12 14 16 VIN(V) Ta=25 Ta=-40 Ta=85
(12)
TPRO-VIN S-8520/21(Fosc:60 kHz) 30 26 22 TPRO (ms) 18 14 10 6 2 4 6 8 10 12 14 16 VIN(V) Ta=25 Ta=85 Ta=-40
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
(13)
TPRO-VIN S-8520/21(Fosc:180 kHz) 8 7 6 TPRO 5 (ms) 4 3 2 2 4 6 8 10 12 14 16 VIN(V) 1 2 4 6 8 10 12 14 16 VIN(V) Ta=85 Ta=-40 Ta=25 TPRO (ms) 2 3 Ta=25 Ta=-40
(14)
TPRO-VIN S-8520/21(Fosc:300 kHz) 4
Ta=85
(15)
VSH-VIN S-8520/21 1.8 1.6 1.4 VSH 1.2 (V) 1.0 0.8 0.6 0.4 2 4 6 8 10 VIN(V) 12 14 16 Ta=-40 Ta=25
(16)
VSL-VIN S-8520/21 1.7 1.5 1.3 VSL 1.1 (V) 0.9 0.7 0.5 0.3 2 4 6 8 10 VIN(V) Ta=85 12 14 16 Ta=-40 Ta=25
Ta=85
(17)
VOUT-VIN S-8521B30MC (Ta=25C) 3.08 3.07 3.06 3.05 3.04 VOUT 3.03 (V) 3.02 3.01 3.00 2.99 2.98 2 4 6
(18)
VOUT-VIN S-8521B50MC (Ta=25C) 5.08 5.07 5.06 5.05 5.04 VOUT 5.03 (V) 5.02 5.01 5.00 4.99 4.98 2 4 6
IOUT=0.1 mA IOUT=500 mA
IOUT=0.1 mA IOUT=500 mA
IOUT=100 mA
IOUT=100 mA
8 10 VIN(V)
12
14
16
8 10 VIN(V)
12
14
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
(19)
VOUT-VIN S-8521F33MC (Ta=25C) 3.38 3.37 3.36 3.35 3.34 VOUT 3.33 (V) 3.32 3.31 3.30 3.29 3.28 2 4 6
(20)
VOUT-VIN S-8521F50MC (Ta=25C) 5.07 5.06 5.05 5.04 5.03 VOUT 5.02 (V) 5.01 5.00 4.99 4.98 4.97 2 4 6
IOUT=0.1 mA IOUT=100 mA
IOUT=0.1 mA IOUT=100 mA
IOUT=500 mA
IOUT=500 mA
8 10 VIN(V)
12
14
16
8 10 VIN(V)
12
14
16
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series Transient Response Characteristics:
1. Power-On (VIN: 0 V3.6 V or 4.0 V, 0 V9.0 V IOUT: No-load)
S-8520/1C30MC (VIN:0 3.6 V) 10 V VIN (2.5 V/div) 0V 3V VOUT (1 V/div) 0V t(2 ms/div) S-8520/1C30MC (VIN:0 9.0 V) 10 V VIN (2.5 V/div)
0V 3V VOUT (1 V/div) 0V t(2 ms/div)
S-8520/1A30MC (VIN:0 3.6 V) 10 V VIN (2.5 V/div)
S-8520/1A30MC (VIN:0 9.0 V) 10 V VIN (2.5 V/div)
0V 3V VOUT (1 V/div) 0V t(1 ms/div)
0V 3V VOUT (1 V/div) 0V t(1 ms/div)
S-8520/1E33MC (VIN:0 4.0 V) 10 V VIN (2.5 V/div) 0V 3V VOUT (1 V/div) 0V t(1 ms/div)
S-8520/1E33MC (VIN:0 9.0 V) 10 V VIN (2.5 V/div) 0V
3V VOUT (1 V/div) 0V t(1 ms/div)
Seiko Instruments Inc.
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
2. Power-Off Terminal Response (VON/OFF: 0 V1.8 V IOUT : No-load)
S-8520/1C30MC (VIN:3.6 V) 3V VON/OFF 0V 3V VOUT (1 V/div) 0V t(2 ms/div) S-8520/1C30MC (VIN:9.0 V) 3V VON/OFF 0V 3V VOUT (1 V/div) 0V t(2 ms/div)
S-8520/1A30MC (VIN:3.6 V) 3V VON/OFF 0V 3V VOUT (1 V/div) 0V t(1 ms/div)
S-8520/1A30MC (VIN:9.0 V) 3V VON/OFF 0V 3V VOUT (1 V/div) 0V t(1 ms/div)
S-8520/1E33MC (VIN:4.0 V) 3V VON/OFF 0V
S-8520/1E33MC (VIN:9.0 V) 3V VON/OFF 0V
3V VOUT (1 V/div) 0V t(1 ms/div)
3V VOUT (1 V/div) 0V t(1 ms/div)
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
3. Supply Voltage Variation (VIN: 4 V9 V, 9 V4 V)
S-8520/1C33MC (IOUT:10 mA) 10 V VIN (2.5 V/div) S-8520/1C33MC (IOUT:500 mA) 10 V VIN (2.5 V/div) 0V
0V
VOUT (0.2 V/div)
VOUT (0.2 V/div) t(0.5 ms/div) t(0.5 ms/div)
S-8520/1A30MC (IOUT:10 mA) 10 V VIN (2.5 V/div) 0V
S-8520/1A30MC (IOUT:500 mA) 10 V VIN (2.5 V/div)
0V
VOUT (0.2 V/div)
VOUT (0.2 V/div)
t(0.5 ms/div)
t(0.5 ms/div)
S-8520/1E33MC (IOUT:10 mA) 10 V VIN (2.5 V/div)
S-8520/1E33MC (IOUT:500 mA) 10 V VIN (2.5 V/div)
0V
0V
VOUT (0.2 V/div) t(0.5 ms/div)
VOUT (0.2 V/div)
t(0.5 ms/div)
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
4. Load Variation (Vin: 3.6V or 4.0V Iout: 0.1mA500mA, 500mA0.1mA)
S-8520/1C30MC (VIN:3.6 V) 500 mA IOUT 0.1 mA S-8520/1C30MC (VIN:3.6 V) 500 mA IOUT 0.1 mA
VOUT (0.1 V/div)
VOUT (0.1 V/div)
t(0.1 ms/div)
t(5 ms/div)
S-8520/1A30MC (VIN:3.6 V) 500 mA IOUT 0.1 mA
S-8520/1A30MC (VIN:3.6 V) 500 mA IOUT 0.1 mA
VOUT (0.1 V/div)
VOUT (0.1 V/div)
t(0.1 ms/div)
t(10 ms/div)
S-8520/1E33MC (VIN:4.0 V)
500 mA IOUT 0.1 mA
S-8520/1E33MC (VIN:4.0 V)
500 mA IOUT 0.1 mA
VOUT (0.1V/div)
VOUT (0.1 V/div)
t(0.1 ms/div)
t(5 ms/div)
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series External Parts Reference Data:
This reference data is intended to help you select peripheral components to be externally connected to the IC. Therefore, this information provides recommendations on external components selected with a view to accommodating a wide variety of IC applications. Characteristic data is duly indicated in the table below. Table 1 Efficiency Data
Application Inductor Transistor Diode Output No. Product Name Output Capacitor Voltage (V) (F) (1) S-8520B30MC 3.0 TM6201 MA737 47 CD105/47 H IOUT1 A, VIN 10 V (2) S-8520F33MC 3.3 MA720 22 D62F/22 H IOUT0.5 A, VIN 10 V (3) CDH113/22 H IRF7606 MA737 IOUT1 A, VIN 16 V (4) S-8521D30MC 3.0 TM6201 MA720 47x2 CD54/47 F IOUT0.5 A, VIN 10 V Equipment standby mode involved. (5) IRF7606 IOUT0.5 A, VIN 16 V Equipment standby mode involved. TM6201 MA737 47 (6) S-8521B30MC CD105/47 F IOUT1 A, VIN 10 V Equipment standby mode involved. (7) IRF7606 IOUT1 A, VIN 16 V Equipment standby mode involved. (8) S-8521F33MC 3.3 TM6201 MA720 22 D62F/22 H IOUT0.5 A, VIN 10 V Equipment standby mode involved. (9) CDH113/22 H IRF7606 MA737 IOUT1 A, VIN 16 V Equipment standby mode involved. (10) S-8520B50MC 5.0 TM6201 MA720 47 CD54/47 F IOUT0.5 A, VIN 10 V IRF7606 MA737 (11) CD105/47 F IOUT1 A, VIN16 V (12) S-8520F50MC TM6201 MA720 22 D62F/22 H IOUT0.5 A, VIN 10 V (13) CDH113/22 H IRF7606 MA737 IOUT1 A, VIN 16 V (14) S-8521D50MC TM6201 MA720 47x2 CD54/47 F IOUT0.5 A, VIN 10 V Equipment standby mode involved. (15) IRF7606 MA737 CD105/47 F IOUT1 A, VIN 16 V Equipment standby mode involved. (16) S-8521B50MC TM6201 MA720 47 CD54/47 F IOUT0.5 A, VIN 10 V Equipment standby mode involved. IRF7606 MA737 (17) CD105/47 F IOUT1 A, VIN 16 V Equipment standby mode involved. (18) S-8521F50MC TM6201 MA720 22 D62F/22 H IOUT0.5 A, VIN 10 V Equipment standby mode involved. (19) CDH113/22 H IRF7606 MA737 IOUT1 A, VIN 16 V Equipment standby mode involved.
Seiko Instruments Inc.
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
Table 2 Ripple Data
No. Product Name Output Voltage (V) 3.0 3.3
Inductor (H)
Transistor
Rb () 680 - - 680 - -
Cb (pF) 2200 - - 2200 - -
Diode
Output Capacitor (F) 47x2 22 x2 22 47 x2 22 x2 22
(20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31)
S-8520D30MC S-8521D30MC S-8520B30MC S-8521B30MC S-8520F33MC S-8521F33MC S-8520D50MC S-8521D50MC S-8520B50MC S-8521B50MC S-8520F50MC S-8521F50MC
5.0
CD105/47 2SA1213Y CDH113/22 IRF7606 CD105/47 2SA1213Y CDH113/22 IRF7606
MA720 MA737
MA720 MA737
Table 3 Performance Data Component Product Name CD54 CD105
CDH113 D62F MA720 MA737 F93 TE
DC Manufacturer's L-Value Name (H) Resistance () Sumida Electric Co., Ltd
Toko Matsushita Electronics Corporation
Inductor
47
0.37 0.17 0.09 0.25
Max. Allowable Current (A) 0.72 1.28 1.44 0.70
Dia. (mm) 5.8 10.0 11.0 6.0
Height (mm) 4.5 5.4 3.7 2.7
22
Diode
Forward current 500 mA (When VF = 0.55 V) Forward current 1.5 A (When VF = 0.5 V)
Output Capacity
Nichicon Matsushita Electronics Corporation External Transistor 2SA1213Y Toshiba (Bipolar PNP) Corporation External Transistor TM6201 Toyota Automatic (MOS FET) Loom Works, Ltd. IRF7606 International Rectifier
VCEO 50 V max. , IC-2A max., hFE 120 to 240 SOT-89-3 PKG VGS 12 V max. , ID -2 A max. , Vth -0.7 V min. , Ciss 320 pF typ. Ron 0.25 max.(Vgs=-4.5 V), SOT-89-3 PKG VGS 20 V max. , ID -2.4 A max. , Vth -1 V min. Ciss 470 pF typ. Ron 0.15 max.(Vgs=-4.5 V), Micro 8 PKG
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
1. Efficiency Characteristics (1)
S-8520B30MC IOUT - Efficiency (CD105/47 H,TM6201) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=3.6 V VIN=9.0 V 0.1 1 10 IOUT (mA) 100 1000
(2)
S-8520F33MC IOUT - efficiency (D62F/22 H,TM6201) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=9 V VIN=6 V VIN=4 V
(3)
S-8520F33MC IOUT - Efficiency (CDH113/22 H,IRF7606) 100 VIN=14 V 90 80 70 60 50 0.01 VIN=9 V VIN=6 V Efficiency (%) VIN=4 V
0.1
1
10 IOUT (mA)
100
1000
0.1
1
10 IOUT (mA)
100
1000
(4)
S-8521D30MC IOUT - Efficiency (CD54/47 H,TM6201) 100 90 80 70 60 50 0.01 VIN=3.6 V VIN=9.0 V 0.1 1 10 IOUT (mA) 100 1000
(5)
S-8521D30MC IOUT - Efficiency (CD54/47 H,IRF7606) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=3.6 V VIN=9.0 V 0.1 1 10 IOUT (mA) 100 1000
Efficiency (%)
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
(6)
S-8521B30MC IOUT - Efficiency (CD105/47 H,TM6201) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=3.6 V VIN=9.0 V 0.1 1 10 IOUT (mA) 100 1000 50 0.01 0.1 1 10 IOUT (mA)
(7)
S-8521B30MC IOUT - Efficiency (CD105/47 H,IFR7606) 100 90 80 70 60 VIN=3.6 V VIN=9.0 V 100 1000
Efficiency (%)
(8)
S-8521F33MC IOUT - Efficiency (D62F/22 H,TM6201) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=9 V VIN=6 V VIN=4 V
(9)
S-8521F33MC IOUT - Efficiency (CDH113/22 H,IRF7606) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=14 V VIN=9 V VIN=6 V VIN=4 V
0.1
1
10 IOUT (mA)
100
1000
0.1
1
10 IOUT (mA)
100
1000
(10)
S-8520B50MC IOUT - Efficiency (CD54/47 H,TM6201) 100 90 Efficiency 80 (%) 70 60 50 0.01
(11)
S-8520B50MC IOUT - Efficiency (CD105/47 H,IRF7606) 100 90 80 70 VIN=6.0 V VIN=9.0 V 0.1 1 10 IOUT (mA) 100 1000 50 0.01 0.1 1 10 IOUT (mA) 100 1000 60 VIN=14 V VIN=9 V VIN=6 V
Efficiency (%)
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
(12)
S-8520F50MC IOUT - Efficiency (D62F/22 H,TM6201) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=9 V VIN=6 V
(13)
S-8520F50MC IOUT - Efficiency (CDH113/22 H,IRF7606) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=14 V VIN=9 V VIN=6 V
0.1
1
10 IOUT (mA)
100
1000
0.1
1
10 IOUT (mA)
100
1000
(14)
S-8521D50MC IOUT - Efficiency (CD54/47 H,TM6201) 100 90 Efficiency 80 (%) 70 60 50 0.01
(15)
S-8521D50MC IOUT - Efficiency (CD105/47 H,IRF7606) 100 90 Efficiency 80 (%) 70 VIN=14 V VIN=6.0 V VIN=9.0 V 0.1 1 IOUT (mA) 10 100 1000 50 0.01 0.1 1 10 IOUT (mA) 60 VIN=9 V VIN=6 V 100 1000
(16)
S-8521B50MC IOUT - Efficiency (CD54/47 H,TM6201) 100 90 Efficiency 80 (%) 70 60 50 0.01
(17)
S-8521B50MC IOUT - Efficiency (CD105/47 H,IRF7606) 100 90 Efficiency 80 (%) 70 VIN=6.0 V VIN=9.0 V 0.1 1 10 IOUT (mA) 100 1000 50 0.01 0.1 1 10 IOUT (mA) 100 1000 60 VIN=14 V VIN=9 V VIN=6 V
Seiko Instruments Inc.
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
(18)
S-8521F50MC IOUT - Efficiency (D62F/22 H,TM6201) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=9 V VIN=6 V
(19)
S-8521F50MC IOUT - Efficiency (CDH113/22 H,IRF7606) 100 90 Efficiency 80 (%) 70 60 50 0.01 VIN=14 V VIN=9 V VIN=6 V
0.1
1
10 IOUT (mA)
100
1000
0.1
1
10 IOUT (mA)
100
1000
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Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
2. Ripple Voltage Characteristics(L:CD105/47F, Tr:2SA1213, SBD:MA720) (20)
Vrip-VIN S-8520D30MC(COUT:47 Fx2) 240 200 160 Vrip 120 (mV) 80 40 0 2 4 6 8 10 12 14 16 VIN(V) IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(21)
Vrip-VIN S-8521D30MC(Cout:47 Fx2) 240 200 160 Vrip 120 (mV) 80 40 0 2 4 6 8 10 12 14 16 VIN(V) IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(22)
Vrip-VIN S-8520B30MC(COUT:22 Fx2) 240 200 160 Vrip 120 (mV) 80 40 0 2 4 6 8 10 12 14 IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(23)
Vrip-VIN S-8521B30MC(COUT:22 Fx2) 240 200 160 Vrip 120 (mV) 80 40 0 16 2 4 6 8 10 12 14 16 VIN(V) VIN(V) IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(24)
Vrip-VIN S-8520F33MC(COUT:22 F) 240 200 160 Vrip 120 (mV) 80 40 0 2 4 6 8 10 12 14 IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(25)
Vrip-VIN S-8521F33MC(COUT:22 F) 240 200 160 Vrip 120 (mV) 80 40 0 16 2 4 6 8 10 12 14 16 VIN(V) VIN(V) IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
Seiko Instruments Inc.
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series Rev.7.4_10
(26)
Vrip-VIN S-8520D50MC(COUT:47 Fx2) 240 200 160 Vrip 120 (mV) 80 40 0 2 4 6 8 10 12 14 16 VIN(V) IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(27)
Vrip-VIN S-8521D50MC(COUT:47 Fx2) 240 200 160 Vrip 120 (mV) 80 40 0 2 4 6 8 10 12 14 16 VIN(V) IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(28)
Vrip-VIN S-8520B50MC(COUT:22 Fx2) 240 200 160 Vrip 120 (mV) 80 40 0 2 4 6 8 10 12 14 IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(29)
Vrip-VIN S-8521B50MC(COUT:22 Fx2) 240 200 160 Vrip 120 (mV) 80 40 0 16 2 4 6 8 10 12 14 16 VIN(V) VIN(V) IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(30)
Vrip-VIN S-8520F50MC(COUT:22 F) 240 200 160 Vrip 120 (mV) 80 40 0 2 4 6 8 10 12 14 IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
(31)
Vrip-VIN S-8521F50MC(COUT:22 F) 240 200 160 Vrip 120 (mV) 80 40 0 16 2 4 6 8 10 12 14 16 VIN(V) VIN(V) IOUT=500 mA IOUT=100 mA IOUT=0.1 mA
32
Seiko Instruments Inc.
PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4_10 S-8520/8521 Series
3. PWM/PFM (5)
S-8521D30MC PWM/PFM switching characteristics 14
(7)
S-8521B30MC PWM/PFM switching characteristics 14
10 VIN (V) 6 VIN (V)
10
6
2 1 10 IOUT (mA) 100 1000
2 1 10 IOUT (mA) 100 1000
(9)
S-8521F33MC PWM/PFM switching characteristics 14
(15)
S-8521D50MC PWM/PFM switching characteristics 14
10 VIN (V) VIN (V)
10
6
6
2 1 10 IOUT (mA) 100 1000
2 1 10 IOUT (mA) 100 1000
(17)
S-8521B50MC PWM/PFM switching characteristics 14
(19)
S-8521F50MC PWM/PFM switching characteristics 14
10 VIN (V) VIN (V)
10
6
6
2 1 10 IOUT (mA) 100 1000
2 1 10 IOUT (mA) 100 1000
Seiko Instruments Inc.
33
n SOT-23-5
l Dimensions
2.90.2 1.90.2
5 4
MP005-A
010907
Unit : mm
1
2
3
0.16 -0.06
+0.1
0.950.1 0.40.1 No. MP005-A-P-SD-1.1
l Tape Specifications
4.00.1(10-pitches total: 40.00.2)
+0.1
l Reel Specifications
0.270.05
o1.5-0
2.00.05
3000 pcs./reel
12.5max.
3max.
o1.0 +0.1
-0
4.00.1
1.40.2
o60
+0 o180 -3 +1 -0
3.250.15
T2
3 21 45
Winding core
o130.2
9.00.3
20.2 (60) (60)
Feed direction No. : MP005-A-C-SD-1.0
No. MP005-A-R-SD-1 0
* * * * * *
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 mass-production design. When the products described herein are regulated products subject to the Wassenaar Arrangement or other agreements, they may not be exported without authorization from the appropriate governmental authority. Use of the information described herein for other purposes and/or reproduction or copying without the express permission of Seiko Instruments Inc. is strictly prohibited. The products described herein cannot be used as part of any device or equipment affecting the human body, such as exercise equipment, medical equipment, security systems, gas equipment, or any apparatus installed in airplanes and other vehicles, without prior written permission of Seiko Instruments Inc. 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 malfunction prevention, to prevent any accidents, fires, or community damage that may ensue.

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