Rev.7.4 10 PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers S-8520/8521 Series m@ Features: Low current consumption: The S-8520/8521 Series consists of CMOS step-down switching regulator- controllers with PWM-control (S-8520) and PWM/PFIM-switched control (S- 8521). 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, itis also ideal when operating via an AC adapter. @ Applications: e On-board power supplies of battery devices for In operation: 60 uA max. (A & B Series) portable telephones, electronic notebooks, PDAs, 21 WA max. (C & D Series) and the like. 100 uA max. (E & F Series) e Power supplies for audio equipment, including When powered off: 0.5 uA max. portable CD players and headphone stereo Input voltage: equipment. | 25Vto16V(B,D,F Series) Fixed voltage power supply for cameras, video 2.5 V to 10 V (A, C, E Series) equipment and communications equipment. Output voltage: Power supplies for microcomputers. Selectable between 1.5 V and e Conversion from four NiH or NiCd cells or two 6.0 Vin 0.1 Vstep lithium-ion cells to 3.3 V/3 V. Duty ratio: e Conversion of AC adapter input to 5 V/3 V. 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.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 m@ Block Diagram: . rr} s IN 5, L VIN Oscillation Reference Voltage Circuit Source with Soft Start VOUT EXT. ae A PWM or : PWM/PFM- + Switched Control A VIN + SD A Circuit 77 Cw - Court 7a Von ior VSS me me we ON / OFF ve m@ Selection Guide: 1. Product Name S$ -852X XXX MC - XXX Note: The diode inside the IC is a parasitic diode. Figure 1 Block Diagram 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: Oscillattn frequency of 180 kHz, without overload protection circuit. 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/PFI-switched control Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 2. Product List (As of September 1, 2000) A & B Series (Oscillation Frequency of 180 KHz) Item S-8520AXXMC S-8521 AXXMC S-8520BXXMC $-8521BXXMC Output Voltage Series Series Series Series (Vv) 1.6 1.8 S-8520B18MC-ARD-T2 | S-8521B18MC-ATD-T2 1.9 S$-8521B19MC-ATE-T2 2.0 S$-8521 B20MC-ATF-T2 2.1 S-8520A21MC-AVG-T2 $-8521B21MC-ATG-T2 2.5 S-8520A25MC-AVK-T2 | S-8521A25MC-AXK-T2 | S-8520B25MC-ARK-T2 | S-8521B25MC-ATK-T2 2.7 S$-8520A27MC-AVM-T2 | S-8521A27MC-AXM-T2 | S-8520B27MC-ARM-T2 | S-8521B27MC-ATM-T2 2.8 S-8520A28MC-AVN-T2 | S-8521A28MC-AXN-T2 | S-8520B28MC-ARN-T2 | S-8521B28MC-ATN-T2 2.9 $-8520A29MC-AVO-T2 | S-8521A29MC-AXO-T2 | S-8520B29MC-ARO-T2 | S-8521B29MC-ATO-T2 3.0 S-8520A30MC-AVP-T2 | S-8521A30MC-AXP-T2 | S-8520B30MC-ARP-T2 | S-8521B30MC-ATP-T2 3.1 $-8520A31MC-AVQ-T2 | S-8521A31MC-AXQ-T2 | S-8520B31MC-ARQ-T2 | S-8521B31MC-ATQ-T2 3.2 S-8520A32MC-AVR-T2 | S-8521A32MC-AXR-T2 | S-8520B32MC-ARR-T2 | S-8521B32MC-ATR-T2 3.3 S-8520A33MC-AVS-T2 | S-8521A33MC-AXS-T2 | S-8520B33MC-ARS-T2 | S-8521B33MC-ATS-T2 3.4 S-8520A34MC-AVT-T2 | S-8521A34MC-AXT-T2_ | S-8520B34MC-ART-T2 | S-8521B34MC-ATT-T2 3.5 $-8520A35MC-AVU-T2 | S-8521A35MC-AXU-T2 | S-8520B35MC-ARU-T2 | S-8521B35MC-ATU-T2 3.6 S-8520A36MC-AVV-T2 | S-8521A36MC-AXV-T2 | S-8520B36MC-ARV-T2 | S-8521B36MC-ATV-T2 5.0 S-8520A50MC-AWJ-T2 | S-8521A50MC-AYJ-T2 | S-8520B50MC-ASJ-T2 | $-8521B50MC-AUJ-T2 C & D Series (Oscillation Frequency of 60 kHz) Item S-8520CXXMC $-8521CXXMC S-8520DXXMC S-8521 DXXMC Output Voltage Series Series Series Series (V) 1.6 S$-8521C16MC-BTB-T2 S-8521D16MC-BXB-T2 2.0 S-8521D20MC-BXF-T2 2.5 $-8520C25MC-BRK-T2_ |S-8521C25MC-BTK-T2 _|S-8520D25MC-BVK-T2_|S-8521D25MC-BXK-T2 2.7 $-8520C27MC-BRM-T2_ |S-8521C27MC-BTM-T2_ |S-8520D27MC-BVM-T2_ |S-8521D27MC-BXM-T2 2.8 $-8520C28MC-BRN-T2_|S-8521C28MC-BTN-T2 |S-8520D28MC-BVN-T2_|S-8521D28MC-BXN-T2 2.9 $-8520C29MC-BRO-T2_ |S-8521C29MC-BTO-T2 |S-8520D29MC-BVO-T2 |S-8521D29MC-BXO-T2 3.0 $-8520C30MC-BRP-T2_|S-8521C30MC-BTP-T2 _|S-8520D30MC-BVP-T2_|S-8521D30MC-BXP-T2 3.1 $-8520C031MC-BRQ-T2 |S-8521C31MC-BTQ-T2 |S-8520D31MC-BVQ-T2_ |S-8521D31MC-BXQ-T2 3.2 $-8520C32MC-BRR-T2_|S-8521C32MC-BTR-T2 |S-8520D32MC-BVR-T2_|S-8521D32MC-BXR-T2 3.3 $-8520C33MC-BRS-T2_ |S-8521C33MC-BTS-T2 _|S-8520D33MC-BVS-T2_ |S-8521D33MC-BXS-T2 3.4 $-8520C34MC-BRT-T2_|S-8521C34MC-BTT-T2 _|S-8520D34MC-BVT-T2_|S-8521D34MC-BXT-T2 3.5 $-8520C35MC-BRU-T2_|S-8521C35MC-BTU-T2 |S-8520D35MC-BVU-T2 |S-8521D35MC-BXU-T2 3.6 $-8520C36MC-BRV-T2_ |S-8521C36MC-BTV-T2 |S-8520D36MC-BVV-T2_ |S-8521D36MC-BXV-T2 5.0 S-8520C50MC-BSJ-T2 |S-8521C50MC-BUJ-T2 _|S-8520D50MC-BW/J-T2 |S-8521D50MC-BYJ-T2 E & F Series (Oscillation Frequency of 300 KHz) Item S-8520EXXMC $-8521EXXMC S-8520F XXMC S-8521 FXXMC Output Voltage Series Series Series Series (Vv) 1.5 S-8521E15MC-BLA-T2 1.8 $-8520E18MC-BJD-T2 |S-8521E18MC-BLD-T2 _|S-8520F18MC-BND-T2_ |S-8521F18MC-BPD-T2 2.0 S-8521E20MC-BLF-T2 2.5 S-8520E25MC-BJK-T2 S-8520F25MC-BNK-T2 2.7 S-8520F27MC-BNM-T2 3.0 S-8520E30MC-BJP-T2 |S-8521E30MC-BLP-T2 _|S-8520F30MC-BNP-T2_ |S-8521F30MC-BPP-T2 3.3 S-8520E33MC-BJS-T2 |S-8521E33MC-BLS-T2 _|S-8520F33MC-BNS-T2_|S-8521F33MC-BPS-T2 3.4 S-8520F34MC-BNT-T2 3.5 S-8521E35MC-BLU-T2 5.0 S-8520E50MC-BKJ-T2 |S-8521E50MC-BMJ-T2 _|S-8520F50MC-BOJ-T2 _|[S-8521F50MC-BQJ-T2 For the availability of product samples listed above, contact the SII Sales Department. Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 m@ Pin Assignment: SOT-23-5 Pin No. |Pin Name Function Top view Power-off pin 5 4 1 ON/OFF H: Normal operation (Step-down operation) Fy Fy L: Step-down operation stopped (All circuits deactivated) 2 VSS __ |GND pin 3 VOUT [Output voltage monitoring pin 4 EXT Connection pin for external transistor i | 5 VIN IC power supply pin 1 2 3 Figure 2 m@ Absolute Maximum Ratings: (Ta=25 C unless otherwise specified) Item Symbol Ratings Unit VIN pin voltage Vin Veg 0.3 to Vsg+12 or Vegt18 V VOUT pin voltage Vout Vsg 0.3 to Vgst12 or Vsst18 V ON/OFF pin voltage VoMorr Veg 0.3 to Vegt12 or Vegt18 V EXT pin voltage Vext Vg 0.3 to Vint 0.3 V EXT pin current lee +50 mA Power dissipation Pp 250 mW Operating temperature range Topr 40 to +85 C Storage temperature range Tstc 40 to +125 C *1. Vsst12 V for S-8520/21 A/C/E; Vsst+18 V for S-8520/21 B/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. 4 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 m@ Electrical Characteristics: 1. S-8520/21 A & B Series $-8520/8521 Series (Ta =25 C, unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Units | Measurement Circuit Output voltage | Vout(E) - Vour(S) | Vour(S) | Vour(S) v 3 x 0.976 x1.024 Input voltage VIN IS-8520/21A Series 25 - 10.0 Vv 2 IS-8520/21B Series 25 - 16.0 Current consumption 1 Iss4 Mout = Vout(S) x 1.2 = 35 60 LA 2 Current consumption during Isss Monorr = 0 V - - 05 HA 2 power off S-8520/21X15 24 2.3 -4.5 - S-8520/21 X25 34 -3.7 -7.0 - lextH = [Vext=Vin-0.4 V S-8520/21 X35 44 5.3 -9.3 - S-8520/21 X45 54 -6.7 -11.3 - EXT pin output current S-8520/21 X55 60 -8.0 13.3 = mA _ S-8520/21X15 24 44.3 +8.4 - S-8520/21 X25 34 +7.0 +13.2 - lextt = [Vext=0.4V S-8520/21 X35 44 +9.9 417.5 - IS-8520/21X45 54 | 412.6 | +21.4 - IS-8520/21X55 60 | +15.0 | +25.1 - Line regulation AVoutt_ [Vin = Vour(S) x1.2 to x1.4 * = 30 60 mV 3 Load regulation AVoutz2 |Load current =10y/A to lout(See below) - 30 60 mV 3 x1.25 Output voltage temperature] AVour |Ta= 40C to 85C - +Vour(S) - VIPC 3 coefficient /ATa x 5E-5 Oscillation frequency fosc |Measure waveform |Vour(S) = 2.5 V 153 180 207 kHz 3 at EXT pin Mout(S) = 2.4 V 144 180 216 PWIM/PFM-control switch PFM Duty |Measure waveform at EXT pin under no 15 25 40 % 3 duty ratio load. Power-Off pin VsuH Evaluate oscillation at EXT pin 1.8 - - Vv 2 input voltage Vsi Evaluate oscillation stop at EXT pin - - 03 Power-Off pin Isu - -0.1 - 0.1 LA 1 input leakage current Ist = -0.1 = 0.1 pA 1 Soft-Start time Tss - 4.0 8.0 16.0 ms 3 Overload detection time ~ Tpro |Duration from the time Vout is reduced 2.0 4.0 8.0 ms 2 ito O V to the time the EXT pin obtains NIN. Efficiency EFFI - - 93 - % 3 Conditions: The recommended components are connected to the IC, unless otherwise indicated. Vin = Vout(S) x 1.2 [V], lout = 120 [mA] (Vin= 2.5 V, if Vour(S) <2.0 V.) Peripheral components: Coil Diode Capacitor Transistor Base resistance (Rp) Base capacitor (Cp) : Sumida Electric Co., Ltd. CD54 (47 uwH). : Matsushita Electronics Corporation MA720 (Schottky type). : Matsushita Electronics Corporation TE (16 V, 22 uF tantalum type). : Toshiba Corporation 2SA1213Y. : 0.68 kQ : 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. Vour(S) Specified output voltage value. Vour(E) Actual output voltage value. *2. *3. *4. Applicable to the S-8521A Series and S-8521B Series. Applicable to the S-8520A Series and S-8521A Series. Vin = 2.5 V to 2.94 V, if Vout(S) <2.0 V. Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 2. $-8520/21 C & D Series (Ta =25 C unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Units |Measuremen t Circuit Output voltage Vour(E) - Vour(S) | Vout(S) | Vour(S) Vv 3 x 0.976 x 1.024 Input voltage Vin IS-8520/21C Series 2.5 - 10.0 V 2 S-8520/21D Series 2.5 - 16.0 Current consumption 1 Issi ouT= Vout(S) x 1.2 = 10 21 LA 2 Current consumption during Isss ON/OFF =O V - - 0.5 HA 2 power-off S-8520/21X15 24 2.3 -4.5 - S-8520/21 X25 34 3.7 -7.0 - lEXTH ExT = Vin-0.4 VV S-8520/21X35 44 5.3 -9.3 - S-8520/21 X45 54 -6.7 -11.3 - EXT pin output current S-8520/21 X55 60 -8.0 13.3 - mA _ S-8520/21X15 24 44.3 +8.4 - S-8520/21 X25 34 +7.0 +13.2 - lEXTL ExT =0.4V S-8520/21 X35 44 +9.9 417.5 - S-8520/21 X45 54 +12.6 +21.4 - S-8520/21 X55 60 +15.0 +25.1 - Line regulation AVout: [Vin = Vour(S) x1.2 to x1.4 4% = 30 60 mV 3 Load regulation AVoutz |Load current =10 UA to lout(See below) - 30 60 mV 3 1.25 Output voltage temperature | AVout ta =40 C to 85C = + Vout(S) = VPC 3 coefficient /ATa ~ x 5E-5 Oscillation frequency fosc Measure waveform |Vour(S) = 2.5 V 48 60 72 kHz 3 lat EXT pin out(S) <= 2.4 V 45 60 75 PWM/PFM-control switch PFM_ |Measure waveform at EXT pin under no 15 25 40 % 3 duty ratio 2 Duty _ load. Power-Off pin VsH [Evaluate oscillation at EXT pin 1.8 - - V 2 input voltage Vs. [Evaluate oscillation stop at EXT pin - - 0.3 Power-Off pin Isu - -0.1 - 0.1 vA 1 input leakage current Ist = -0.1 = 0.1 LA 1 Soft-Start time Tss - 6.0 12.0 24.0 ms 3 Overload detection time ~ Tpro Duration from the time Vout is reduced 7.0 14.0 28.0 ms 2 ito 0 V to the time the EXT pin obtains IN. Efficiency EFFI - - 93 - % 3 Conditions: The recommended components are connected to the IC, unless otherwise indicated. Vin = Vout x 1.2 [V], lout = 120 [mA] (Vin= 2.5 V, if Vour(S) <2.0 V.) Peripheral components: Coil : Sumida Electric Co., Ltd. CD54 (47 uH). Diode : Matsushita Electronics Corporation MA720 (Schottky type). Capacitor : Matsushita Electronics Corporation TE (16 V, 22 uF tantalum type). Transistor : Toshiba Corporation 2SA1213Y. Base resistance (Rp) : 0.68 kQ Base capacitor (Cp) : 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. Vour(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 Vour(S) $2.0 V. 6 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 3. $-8520/21 E & F Series $-8520/8521 Series (Ta = 25 C unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Units | Measurement Circuit Output voltage Vout(E) - Vout(S) | Vour(S) | Vour(S) Vv 3 x0.976 x 1.024 Input voltage Vin S-8520/21E Series 2.5 - 10.0 V 2 IS-8520/21F Series 2.5 - 16.0 Current consumption 1 Issi Mout = Vout(S) x 1.2 = 60 100 LA 2 Current consumption during Isss Vonorr = 0 V - - 0.5 LA 2 power-off IS-8520/21X15-24] -2.3 -4.5 - IS-8520/21X25 - 34] -3.7 -7.0 - lextH =|Vext=Vin-0.4V_ [S-8520/21X35- 44] -5.3 -9.3 - IS-8520/21X45 -54] -6.7 -11.3 - EXT pin output current S-8520/21X55 60 -8.0 13.3 = mA _ IS-8520/21X15-24] +4.3 +8.4 - IS-8520/21X25 34] +7.0 $13.2 - lex. |VEXT=0.4V IS-8520/21X35 - 44] +9.9 417.5 - IS-8520/21X45 54] +12.6 +21.4 - IS-8520/21X55 60 | +15.0 +25.1 - Line regulation AVout:_ [Vin =Vour(S) x1.2 to x1.4 4 = 30 60 mV 3 Load regulation AVoutz |Load current =10 UA to lour(See below) - 30 60 mV 3 x1.25 Output voltage temperature AVoutT Ta =-40 C to 85 C - + Vout - VPC 3 coefficient /ATa x 5E-5 Oscillation frequency fosc |Measure waveform|Vour = 2.5 V 240 300 360 kHz 3 at EXT pin Mout $2.4V 225 300 375 PVW/M/PFM-control switch |PFM Duty|Measure waveform at EXT pin under no 15 25 40 % 3 duty ratio 2 load. Power-Off pin VsH Evaluate oscillation at EXT pin 1.8 - - V 2 input voltage Vsi Evaluate oscillation stop at EXT pin - - 0.3 Power-Off pin Isu - -0.1 - 0.1 LA 1 input leakage current Ist - -0.1 - 0.1 LA 1 Soft-Start time Tss - 2.0 45 9.2 ms 3 Overload detection time Tpro Duration from the time Vout is reduced 1.3 2.6 4.5 ms 2 to O V to the time the EXT pin obtains MIN. Efficiency EFFI - - 90 - % 3 Conditions: The recommended components are connected to the IC, unless otherwise indicated. Vij = Vout x 1.2 [V], lout = 120 [mA] (Vin= 2.5 V, if Vour(S) <2.0 V.) Peripheral components: Coil : Sumida Electric Co., Ltd. CD54 (47 uH). Diode : Matsushita Electronics Corporation MA720 (Schottky type). Capacitor : Matsushita Electronics Corporation TE (16 V, 22 uF tantalum type). Transistor : Toshiba Corporation 2SA1213Y. Base resistance (Rp) : 0.68 kO Base capacitor (Cp) : 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 $-8521, unless otherwise noted. *1. Vout(S) Specified output voltage value. Vout(E) Actual output voltage value. *2. Applicable to the S-8521 E 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 Vour(S) <2.0 V. Seiko Instruments Inc. 7PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 m@ Measurement Circuits: 1 | open 2 Open vin. EXT -yourTy VIN EXT VOUT _ ___ _ WT Wr 0.68 kQ 2200 pF VIN EXT VOUT fe ONIOFF gg I Figure 3 m@ Operation: 1. 1.1 PWM Control (S-8520 Series) Step-Down DC-DC Converter 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 wA, these DC/DC converters can operate at extremely high efficiency. Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 $-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 | CR Oscillation | Output Circuit Voltage __ ON/OFF H Activated Set value L? Deactivated 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. $-8520A33MC (Vin:0 4.0 V) Power switched on 3V Vout (1 Vidiv) OV 1.5A Rush current (0.5 A/div) OA 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. 9PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 Waveforms at EXT pin 5. 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. le p< > \ > > Overload detection time Protection circuit ON (Tero) (Tss x 0.3) Figure 6 Waveforms Appearing at EXT Pin As the Overload Protection Circuit Operates 100 % Duty Cycle The S-8520/21 Series operates with a maximum duty cycle of 100 %. When aB, 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. Ifan 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. m Selection of Series Products and Associated External Components 1. 10 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/PFM- switched 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/PFM- switched 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 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 $-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 uA. (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). S-8520 $-8521 A |B] C DIE A B Cc D E An overload protection sk sk sk sk sk sk circuit is required The input voltage range ik sk ok ve ve exceeds 10 V The efficiency under light O O O O 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) oO] Oo Oo} O It is important to have a O O low-ripple voltage Importance is attached to} GQ | O O O the downsizing of external components 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. Oo} O Oo} O O} O| O O} O| O 2. Inductor The inductance value greatly affects the maximum output current Iout and the efficiency 7. As the L-value is reduced gradually, the peak current |, increases, to finally reach the maximum output current lou; when the L-value has fallen to a certain point. If the L-value is made even smaller, lout 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 |,, 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 47uWH, E, F Series 22 uH 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. 11PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 5.1 12 Therefore, select an inductor in which the peak current I,, will not surpass its allowable current at any moment. The peak current I,, is represented by the following equation in continuous operation mode: (Vout + Ve) (Vin = Vout) 2 x fose x L x (Vin + Ve) lpK = lour + Where fosc is the oscillation frequency, L the inductance value of the coil, and V; the forward voltage of the diode. 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 Ipx. Capacitors (C\y, Cour) The capacitor inserted on the input side (C\,) serves to lower the power impedance and to average the input current for better efficiency. Select the C,,y-value according to the impedance of the power supplied. As a rough rule of thumb, you should use a value of 47uF to 100 uF, although the actual value will depend on the impedance of the power in use and the load current value. For the output side capacitor (Cour), 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 Q), 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 47uF to 100 uF can serve as a rough yardstick for this selection. 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. 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 Vix 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 on- resistance of the MOS FET. Therefore, if the efficiency under heavy loads is particularly important for Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 $-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 Ip. 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 25A1213-Y for the bipolar transistor (PNP). The driving capacity for increasing the output current by means of a bipolar transistor is determined by the hre-value and the R,-value of that bipolar transistor. 28A1213-Y NZ vin I Rp Cy! I EXT Vin | I I LLL e. Figure 7 The R,-value is given by the following equation: V0.7 __0.4 lp lextcl Ry= Find the necessary base current Ib using the hfe - value of bipolar transistor by the equation, |, = Ip/Nre, and select a smaller R,-value. A small R,-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 C, is inserted in parallel with resistance R,, as shown in Figure 7, the switching loss will be reduced, leading to a higher efficiency. Select a C,-value by using the following equation as a guide: 4 C, < 27 XRy X foscX 0.7 However, the practically-reasonable C, value differs depending upon the characteristics of the bipolar transistor. Optimize the C, value based on the experiment result. Seiko Instruments Inc. 13PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 mw Standard Circuits: (1) Using a bipolar transistor: | VIN Oscillation Reference Voltage Circuit Source with Soft-Start VOUT *S os iz | +H T EXT PWM or I oh PWM/PFM- + - Switched Control mm Vin + sD F Circuit Cn P 7 Cour ON / OFF Voniok 2 _ vss wa Figure 8 (2) Using a Pch MOS-FET transistor my LAr L VIN Oscillation Reference Voltage Circuit Source with Soft-Start VOUT A | ) EXT PWM or PWM/PFM- + V + sp oH Switched Control wm Circuit Se yn Sp Cour ON / OFF Von sore fo I Figure 9 m@ Precautions: e Install the external capacitors, diode, coil, and other peripheral components as close to the IC as possible, and secure grounding at a single location. e 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. e 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. e Make sure that dissipation of the switching transistor will not surpass the allowable dissipation of the package. (especially at the time of high temperature) 5 20 5% Vv = 82 100 Pp (mw) 0 0 50 100 150 Temperature Ta (c) Figure 10 Power dissipation of an SOT-23-5 Package (Free-Air) 14 Seiko Instruments Inc.Rev.7.4 10 PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers 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 S- 8520/8521 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, Rg, 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 Rg. aes T Co $-8520/21 Series | Vout Ri R2 Oscillation Cirucuit Figure 11 The S-8520 and 21 Series have an internal impedance of R, and Rz between the VOUT and the VSS pin, as shown in Figure 11. Therefore, the output voltage (OUT) is determined by the output voltage value Vour of the S-8520/21 Series, and the ratio of the parallel resistance value of external resistance Rg and internal resistances R, +R, of the IC, to external resistance Ra. The output voltage is expressed by the following equation: OUT = Vout + Vout X Ra + ( Re // (Ri + Re )) (Note: // denotes a combined resistance in parallel.) The voltage accuracy of the output OUT set by resistances Ra and Rg is not only affected by the IC's output voltage accuracy (Vour +2.4 %), but also by the absolute precision of external resistances Ra and Re in use and the absolute value deviations of internal resistances R, and R2 in the IC. Let us designate the maximum deviations of the absolute value of external resistances Ra and Rg by Ramax and Remax, respectively, the minimum deviations by Ramin and Rgmin, respectively, and the maximum and minimum deviations of the absolute value of internal resistances R; and R>2 in the IC by (Ri+R2)max and (Ri+R.) 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 + ( Rgamax // ( R; + Ro )max ) OUTmax = Vout X 1.024 + Vour x 1.024 x Ramax + ( Ramin // ( R; + Re )min ) The voltage accuracy of the output OUT cannot be made higher than the output voltage accuracy (Vour + 2.4 %) of the IC itself, without adjusting the external resistances Ra and Rg, 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 Re and the absolute value of internal resistances R, and Rz> in the IC. In particular, to suppress the influence of deviations in internal resistances R, and R> in the IC, a major contributor to deviations in the output OUT, the external resistances Ra and Rg must be limited to a much smaller value than that of internal resistances R, and R2 in the IC. Seiko Instruments Inc. $-8520/8521 Series 15PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 16 On the other hand, a reactive current flows through external resistances Ra and Rg. 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 Rg be made sufficiently large. However, too large a value (more than 1 MQ) for the external resistances Ra and Rg 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 R, 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 MQ to 28.9 MQ Output voltage 2.1 V to 2.5 V 4.44 MO to 27.0 MO Output voltage 2.6 V to 3.3 V > 3.60 MQ to 23.3 MO Output voltage 3.4 V to 4.9 V > 2.44 MO to 19.5 MQ Output voltage 5.0 V to 6.0 V > 2.45 MQ to 15.6 MO When a value of R;+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. R, + Ro =2+ (1 + maximum deviation in absolute value of internal resistances R; and R2 in IC + 1 + minimum deviation in absolute value of internal resistances R, and R>2 of IC) Moreover, add a capacitor C- in parallel to the external resistance R, 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: Co (F) = 1+ (2X mx Ra (Q) 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. e SII is equipped with a tool that allows you to automatically calculate the necessary resistance values of Ra and Rg, from the required voltage accuracy of the output OUT. SII will be pleased to assist its customers in determining the Ra and Rg values. Should such assistance be desired, please inquire. e Moreover, SIl 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. Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 $-8520/8521 Series m@ Characteristics of Major Parameters (Typical values): (1) Iss1-Vin $-8520/21(Fosc:60 kHz) 20 15 Iss1 (ua) * 5 (3) Iss1-Vin $-8520/21(Fosce:300 kHz) 60 50 40 Iss1 (way? 20 10 0 2 4 6 8 10 12 14 16 Vin) (5) Fosc-Vin $-8520/21(Fosce:180 kHz) 220 210 200 190 180 170 160 150 140 Fosce (kHz) 2 4 6 8 10 12 14 16 Vin) (2) Iss1-Vin $-8520/21(Fosce:180 kHz) 40 30 Issi (way 2 10 (4) Fosc-Vin $-8520/21(Fosce:60 kHz) 80 75 70 65 Fi osc 60 (kHz) 55 50 45 40 2 4 6 8 10 12 14 16 Vin) (6) Fosc-Vin S-8520/21 (Fose:300 kHz) 360 340 320 Fosce (kHz) 300 280 260 240 Vin) Seiko Instruments Inc. 17PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 (7) (8) lextH-Vin lextt-Vin -60 60 -50 50 40 40 lextH leEXTL 30 (may ~29 (mA) -20 20 -10 10 0 0 2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 Vin(V) Vin(V) (9) (10) Tss-Vin TssVin $-8520/21 (Fose:180 kH $-8520/21(Fosc:60 kHz) : (Fose: Zz) 5 25 20 20 15 Tss 1 Tss ms (ms) 10 (ms) 40 5 5 0 0 2 4 6 8 10 12 14 16 Vin(V) (11) (12) Tss-Vin Tpro-VIN $-8520/21 (Fose:300 kHz) $-8520/21(Fosc:60 kHz) 10 30 8 26 6 22 Tss TpRO 18 (ms) 4 (ms) 14 2 10 0 6 2 4 6 8 10 12 14 16 Vin) Vin(V) 18 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 $-8520/8521 Series (13) (14) Tpro-ViN Tpro-VIN $-8520/21 (Fose:180 kHz) $-8520/21 (Fosc:300 kHz) 8 4 7 6 3 TpRO TPRO (ms) (ms) 4 2 3 2 1 Vin(V) Vin(V) (15) (16) Vsu-Vin Vs_-VIN $-8520/21 $-8520/21 1.8 1.7 1.6 1.5 1.4 1.3 Vey 1.2 Ve 1-1 (Vv) 1.0 ) 0.9 0.8 0.7 0.6 0.5 0.4 0.3 2 4 6 8 10 12 14 16 Vin(V) (17) (18) Vout-Vin Vout-Vin S-8521B30MC (Ta=25C) $-8521BS0MC (Ta=25C) 3.08 5.08 3.07 5.07 3.06 lour=0.1 5.06 3.05 lour=500 5.05 3.04 5.04 Vou 3.03 voy 5-03 ( )3 02 5.02 3.01 5.01 3.00 5.00 2.99 4.99 2.98 4.98 2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 Vin(V) Vin(V) Seiko Instruments Inc. 19PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 (19) (20) Vout-Vin Vout-Vin $-8521F33MC (Ta=25C) $-8521F50MC (Ta=25C) 3.38 5.07 3.37 5.06 3.36 lour=0.1 5.05 lour=0.1 3.35 100 5.04 lour=100 3.34 5.03 vowye33 vow 5-02 3.32 5.01 3.31 5.00 3.30 4.99 3.29 4.98 lour=S00 3.28 4.97 2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 Vin(V) Vin(V) 20 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 $-8520/8521 Series m Transient Response Characteristics: 1. Power-On (Vin: 0 V3.6 V or 4.0 V, 0 V9.0 V_ lout: No-load) S-8520/1C30MC (Vin:0 3.6 V) S-8520/1C30MC (Vin:'O 9.0 V) 10 10V Vin Vin (2.5 Vid (2.5 Vidiv) OV OV 3V 3V Vour Vout (1 Vidiv (1 Vidiv) OV OV t(2 msi/div) t(2 ms/div) S-8520/1A30MC (Vin:0 33.6 V) S-8520/1A30MC (Vin:0 9.0 V) 10V 10V Vin Vin (2.5 Vidiv) (2.5 Vidiv) OV 3V 3V Vout Vout (1 Vidiv) (1 Vidiv) 0 OV t(1 ms/div) t(1 ms/div) S-8520/1E33MC (Vin:0 74.0 V) S-8520/1E33MC (Vin:0 9.0 V) 10V 10V Vin Vin (2.5 Vidiv) (2.5 Vidiv av Ov 3V 3V Vout Vout (1 Vidiv) (1 Vidiv av OV t(1 ms/div) t(1 ms/div) Seiko Instruments Inc. 21PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 2. Power-Off Terminal Response (Vonorr: 0 V1.8 V lout : No-load) S-8520/1C30MC (Vn:3.6 V) 3V VoniorF OV 3V Vout (1 Vidiv) OV t(2 msi/div) S-8520/1A30MC (Vin'3.6 V) 3V Voniorr OV 3V Vour (1 Vidiv OV t(1 ms/div) S-8520/1E33MC (Vin:4.0 V) 3V VoworF OV 3V Vour (1 Vidiv OV t(1 msdiv) 22 S-8520/1C30MC (Vin:9.0 V) 3V VowoFF OV 3V Vout Vv, OV t(2 ms/div) S-8520/1A30MC (Vin:9.0 V) 3V Vo NVOFF OV 3V Vout (1 Vidiv) OV t(1 ms/div) S-8520/1E33MC (Vin:9.0 V) 3V VonioFF OV 3V Vout (1 Vidiv OV t(1 ms/div) Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 $-8520/8521 Series 3. Supply Voltage Variation (Vin: 4 V9 V, 9 V4 V) $-8520/1C33MC (lour: 10 mA) $-8520/1C33MC (lour:500 mA) 10 10V Vin (2.5 Vidiv) Vin (2.5 Vidiv) OV OV Vout (0.2 Vidiv) Vour (0.2 Vidiv) t(0.5 ms/div) (0.5 ms/div) S-8520/1A30MC S-8520/1A30MC (lour:500 mA) (lout: 10 mA 10V 10V Vin Vin (2.5 Vidiv) (2.5 Vidiv OV OV Vout Vour (0.2 Vidiv) (0.2 Vidiv t(0.5 ms/div) t(0.5 ms/div) S-8520/1E33MC (lour:10 mA) S-8520/1E33MC (lour:500 mA) 10V 10V Vin Vin (2.5 Vidiv) (2.5 Vidiv) OV OV Vout (0.2 Vidiv) Vout (0.2 Vidiv t(0.5 msdiv) t(0.5 ms/div) Seiko Instruments Inc. 23PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 4. Load Variation (Vin: 3.6V or 4.0V lout: 0.14mA500mA, 500mA->0.1mA) S-8520/1C30MC (Vin:3.6 V) 500 mA lout 0.1mA Vout (01V t(0.1 ms/div) S-8520/1A30MC (Vin:3.6 V) 500 mA lour 0.1mA Vout (0.1 Vidiv t(0.1 ms/div) S-8520/1E33MC (Vn:4.0 V) 500 mA lout 0.1mA Vout (0.1Vidiv) t(0.1 ms/div) S-8520/1C30MC (Vn:3.6 V) 500 mA lout 0.1mA Vout (0.1 V. t(5 ms/div) S-8520/1A30MC (Vin'3.6 V) 500 mA lout 0.1mA Vour (0.1 Vidiv) t(10 ms/div) S-8520/1E33MC (Vn:4.0 V) 500 mA lout 0.1mA Vout (0.1 Vidiv) t(5 ms/div) 24 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 m@ 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 $-8520/8521 Series No. | Product Name | Output Inductor Transistor | Diode | Output Application oltage (Capacitor ) (UF) (1) |S-8520B30MC} 3.0 | CD105/47 wH | TM6201_ |MA737 47 louts1 A, Vin $10 V (2) |S-8520F33MC} 3.3 D62F/22 WH tT MA720 22 louts0.5 A, Vin $10 V (3) tT T |CDH113/22 uH] IRF7606 |[MA737 tT louts1 A, Vin $16 V (4) |S-8521D30MC} 3.0 CD54/47 uF TM6201 |MA720} 47x2 = | lout<0.5A, Vin <10 V Equipment standby mode involved. (9) tT T tT IRF 7606 T tT lours0.5 A, Vin $16 V Equipment standby mode involved. (6) |S-8521B30MC tT CD105/47 wF |} = TM6201 |MA737 47 louts1 A, Vin <10 V Equipment standby mode involved. (7) T T T IRF7606 T tT lours1 A, Vin $16 V Equipment standby mode involved. (8) |S-8521F33MC} 3.3 D62F/22 WH TM6201 |MA720 22 louts0.5 A, Vins 10 V Equipment standby mode involved. (9) T T |CDH113/22 wH] IRF7606 |MA737 T lour<1 A, Vin $16 V Equipment standby mode involved. (10)}S-8520B50MC| 5.0 CD54/47 WF TM6201 |MA720 47 louts0.5 A, Vins 10 V (11) T T | D105/47 wF | IRF7606 [MA737 T lours1 A, Vins16 V (12)] S-8520F50MC tT D62F/22 WH TM6201 |MA720 22 louts0.5 A, Vin $10 V (13) tT T |CDH113/22 wH] IRF7606 |MA737 Tt lour<1 A, Vin <16 V (14)|S-8521D50MC t CD54/47 uF TM6201_ |MA720} 47x2~ | lours<0.5A, Vin <10 V Equipment standby mode involved. (15) tT T | CD105/47 uF} IRF7606 |MA737 T lours1 A, Vin $16 V Equipment standby mode involved. (16)| S-8521 B50MC tT CD54/47 uF TM6201 |MA720 47 louts0.5 A, Vin <10 V Equipment standby mode involved. (17) tT T | CD105/47 uF} IRF7606 |MA737 T lours1 A, Vin $16 V Equipment standby mode involved. (18)| S-8521F50MC t D62F/22 WH TM6201 |MA720 22 louts0.5 A, Vin $10 V Equipment standby mode involved. (19) tT T 1CDH113/22 wH] IRF7606 |MA737 T lour<1 A, Vin <16V Equipment standby mode involved. Seiko Instruments Inc. 25PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 Table 2 Ripple Data No. Product Name Output Inductor | Transistor Rb Cb Diode Output Voltage (WH) (Q) (pF) Capacitor (V) (LF) (20) $-8520D30MC 3.0 CD105/47 |2SA1213Y} 680 2200 MA720 47x2 (21) | $-8521D30MC Tt Tt Tt Tt Tt tT tT (22) | $-8520B30MC tT tT tT tT tT tT 22 x2 (23) | $-8521B30MC T T T T T tT tT (24) $-8520F33MC 3.3 CDH113/22 | IRF7606 - - MA737 22 (25) | $-8521F33MC T tT tT = = T T (26) $-8520D50MC 5.0 CD105/47 |2SA1213Y| 680 2200 MA720 47 x2 (27) | $-8521D50MC Tt Tt Tt Tt Tt tT tT (28) | $-8520B50MC Tt Tt tT tT tT tT 22 x2 (29) | $-8521B50MC Tt Tt Tt Tt Tt tT tT (30) S-8520F50MC T CDH113/22 | IRF7606 - - MA737 22 (31) | $-8521F50MC Tt Tt Tt - - tT tT Table 3 Performance Data Component Product | Manufacturer's | L-Value DC Max. Dia. Height Name Name (wH) |Resistance| Allowable (mm) (mm) (Q) Current (A) Inductor CD54 =| Sumida Electric 47 0.37 0.72 5.8 4.5 Co., Ltd CD105 tT tT 0.17 1.28 10.0 5.4 CDH113 tT 22 0.09 1.44 11.0 3.7 D62F Toko T 0.25 0.70 6.0 2.7 Diode MA720 Matsushita = [Forward current 500 mA (When V;- = 0.55 V) Electronics Corporation MA737 T Forward current 1.5 A (When V- = 0.5 V) Output Capacity F93 Nichicon TE Matsushita Electronics Corporation External Transistor | 2SA1213Y Toshiba ceo 50 V max. , Ic-2A max., hre 120 to 240 (Bipolar PNP) Corporation |SOT-89-3 PKG External Transistor | TM6201 | Toyota Automatic Ves 12 V max. , Ip -2 A max. , Vin -0.7 V min. , Ciss 320 pF typ. (MOS FET) Loom Works, Ltd. |R., 0.25 Q max.(Vgs=-4.5 V), SOT-89-3 PKG IRF7606 International [Ves 20 V max. , Ip 2.4 A max. , Vin -1 V min. Ciss 470 pF typ. Rectifier Ron 0.15 Q max.(Vgs=-4.5 V), Micro 8 PKG 26 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 1. Efficiency Characteristics (1) S-8520B30MC lour,e 05/47 WH, TM6201 90 1 otiiitl Itt I torrid Efficiency 80 (%) 70 Ti Tot bird torrid 60 ti I Vin=3.6 " Vin=9.0 50 0.01 0.1 1 10 100 1000 lour (MA) (2) S$-8520F33MC lour #22 WH, TM6201 Vine 90 Vine6 Vin=4 Tue Toru rot Tt Efficiency 80 (%) 70 60 1 otra I W Tot duel ToEuedee 50 0.01 0.1 1 10 100 1000 lour (mA) (4) S-8521D30MC lour .TM6201 90 Li 80 Efficiency (%) 70 bean bitin} ain 60 meu Vine3.6 Vi Vine9.0V 50 0.01 0.1 1 10 100 1000 lour (mA) Seiko Instruments Inc. (3) S-8520F33MC lour, Efficiency (CDH113/22 WH. IRF7606) mn N14 V 90 Vin=2 V Vine6 Vo [iii orien a Efficiency 80 | Vin-4 V (%) 70 60 boca Porc ot oven 50 0.01 0.1 1 10 100 1000 lour (mA) (5) S-8521D30MC lout, 1 90 I Titi Toru ToL eee Portree Efficiency 8 (%) 70 60 Poti Toru I Vin=3.6 VT Vin-9.0 V 50 0.01 0.1 1 10 100 1000 lour (mA) 27PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series Rev.7.4 10 (6) (7) S-8521B30MC $-8521B30MC lour, Efficiency (CD105/47 wH.TM6201) lourye 90 90 TOoEreede I PoEiredr Torture Torii Efficiency 80 Efficiency 8 (%) (%) 70 70 60 TOoEreede Tore I Vine3.6 V7 60 Torture torre I Vin=3.6 W Vin-9.0V Vin=9.0 50 50 0.01 0.1 1 10 100 1000 0.01 04 1 10 100 1000 lout (MA) lour (MA) (8) (9) $-8521F33MC $-8521F33MC lout, Efficiency (D62F/22 wH.T M6201) louse 113/22 Vin=9 "Vine 4V 90 Vine6 90 [|] Vin-9 V Vin=4 EEG toruedi tl Vin-6 V Tid torre Efficiency 80 Efficiency80 J ___y,,_ay (%) (%) 70 70 60 TFL EU toruedi PoEeriii ToEbErer 60 I Tl torre torrie Torii 50 50 0.01 0.1 1 10 100 1000 0.01 0.1 1 10 100 1000 lout (MA) lout (MA) (10) (11) S-8520B50MC S-8520B50MC lout .TM6201 lout 05/47 "Vine 90 90 F-}\Vne-9 V Darnall (fn) van Vine6V [a Ti Efficiency 80 Efficiency 80 (%) (%) 70 70 60 60 TOE Tord Torture tft I torrie Torii 50 50 0.01 0.1 1 10 100 1000 0.01 0.4 1 10 100 1000 lour (mA) lout (MA) 28 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 $-8520/8521 Series (12) (13) S-8520F50MC lout, F/22 WH, TM6201 1 Vined 90 Vine6 tori Porat tora Efficiency 80 (%) 70 60 Porat 50 0.01 0.1 1 lour (MA) (14) S-8521D50MC lour ,TM6201 90 1 titi Pordad Efficiency 80 (%) 70 Tote Pordad 60 Pordad 50 0.01 0.1 1 10 lout (mA) (16) S-8521B50MC lourye ,T M6201 90 Tote Efficiency 80 (%) 70 Titi 1 otdii 60 Tote Pordad 50 0.01 0.1 1 10 lour (MA) 100 1000 (15) || Vin=6.0 Vin Vin=9.0 V 100 1000 (17) |] Vin=6.0 VI Vin=9.0 V 100 1000 S-8520F50MC lourye 113/22 mend V 90 Vin=o V Vin=6 V Wit torture Efficiency 80 (%) 70 TP oEdaede Tobia 60 TP oEdaede TE 50 0.01 0.1 1 10 100 1000 lour (mA) S-852 1D50MC lour, it 90 Puri Tord Efficiency 80 (%) 70 60 50 0.01 0.1 1 lour (mA) S-8521B50MC lour, i 1 05/47 a Vnet4v 90 | Viny=9 V Vin-6 V Efficiency 80 (%) 70 60 torre torueue 50 0.01 0.1 1 lour (mA Seiko Instruments Inc. 10 100 mn inal 4 1 [7 Vine9 Vf Vin=6 V 10 100 1000 1000 ) 29PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series (18) (19) S-8521F50MC lout,= 1 /22 WH, TM6201 90 Vin-9 1 titil tot itu wt Vin=6 tori Porte 1ordel Pride Efficiency 80 (%) 70 I Tit I Wt Tot bird Pride 60 Tritt torrie Tot bird Pride 50 0.01 0.1 1 10 100 1000 lour (MA) Rev.7.4 10 S-8521F50MC lour,z 113/22 90 mmm Vin=14 V Vin=9 V Vin-6 V Viti Pore 111i trie Efficiency 80 (%) 70 60 hii bru bora boreiue 50 0.01 0.1 1 10 100 1000 lout (MA) 30 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 $-8520/8521 Series 2. Ripple Voltage Characteristics(L:CD105/47uF, Tr:2SA1213, SBD:MA720) (20) (21) VripVin S-8520D30MC(Court:47 WF x2) 240 200 160 Vrip (mvy 129 80 40 0 2 4 6 8 10 12 14 16 Vin(V) (22) (23) Vrip-Vin S-8520B30MC(Court:22 WFx2) 240 200 160 Vrip (mv) 120 80 40 0 2 4 6 8 10 12 14 16 Vin(V) (24) (25) VripVin S-8520F33MC(Cour:22 LF) 240 200 160 Vrip (mvy 129 80 40 0 Vin(V) Seiko Instruments Inc. Vrip-Vin S-8521D30MC(Cout:47 WF x2) 200 160 Vrip (myy 120 80 40 0 Vrip-Vin $-8521B30MC(Cour:22 UFx2) 240 200 160 Vrip (my 129 80 40 0 Vrip-Vin S-8521F33MC(Cour:22 LF) 240 200 160 Vrip (my) 120 80 40 0 31PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers $-8520/8521 Series (26) (27) Vrip-Vin S-8520D50MC(Cour:47 LF x2) 240 200 160 Vrip (mvy 129 80 40 Vin(V) (28) (29) Vrip-Vin S-8520B50MC(Cour:22 WFx2) 240 200 160 Vrip (mV) 120 80 40 0 (30) (31) Vrip-Vin S-8520F50MC(Cour:22 LF) 240 200 160 Vrip (mv) 120 80 40 Vin(V) Rev.7.4 10 Vrip-Vin S-8521D50MC(Cour:47 WF x2) 240 200 160 Vrip (mvyy 129 80 40 0 Vrip-Vin S-8521B50MC(Cour:22 UF x2) 240 200 160 Vrip (mv) 120 100 mA 80 lour-0.1 mA 40 0 Vrip-Vin S-8521F50MC(Cour:22 LF) 240 200 160 Vrip (my) 120 80 40 0 32 Seiko Instruments Inc.PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers Rev.7.4 10 3. PWM/PFM Cs) S-8521D30MC PWM/PFM switching characteristics 14 Vin 7) 1 10 100 1000 lour (MA) (9) S-8521F33MC PWM/PFM switching characteristics 14 Vin i) 1 10 100 1000 lour (MA) (17) S-8521B50MC PWM/PFM switching characteristics 14 Vin (Vv) 6 1 10 100 1000 lour (MA) $-8520/8521 Series S-8521B30MC PWM/PFM switching characteristics 14 Vin (Vv) 1 10 100 1000 lour (MA) (15) S-8521D50MC PWM/PFM switching characteristics 14 Vin Vv) 1 10 100 1000 lour (mA) (19) S-8521F50MC PWM/PFM switching characteristics 1 10 100 1000 lour (MA) Seiko Instruments Inc. 33# SOT-23-5 MPO005-A - 010907 @ Dimensions Unit : mm 2.9+ 0.2 1.9+ 0.2 o wt | | 2 5 4 1 _Vv ut + | | e] 33 - wo N Tog 1.1+0.1 v Ee =-tt 1.3max | in 0.95 0.1 S 0.4+ 0.1 2 No. MP005-A-P-SD-1.1 @ Tape Specifications @ Reel Specifications 4.0+ 0.1(10-pitches total: 40.04 0.2) 3000 /reel 01.5.9) 2.00.05 ie 0.270.085 Pos./ree = al _ 12.5max. ts 1S xT A= Wels Ell Lag ry) 8 1.40.2 3.254 0.15 T2 301 O00 O Winding core (G8 _r Feed direction No. : MP005-A-C-SD-1.0 No, MP005-A-R-SD-1.