SI-8025JF Data Sheet 27469.12 ih ng rs tc lato i Sw egu R Step-Down to 2.5 V, 1.5 A, DC/DC Converter Designed to meet high-current requirements at high efficiency in industrial and consumer applications; embedded core, memory, or logic supplies; TVs, VCRs, and office or telecommunications equipment, the SI-8025JF dc/dc step-down (buck) converter offers a constant 125 kHz switching frequency essential for low EMI noise. The npn switch is included on the die along with the oscillator, control, and logic circuitry requiring only four external components for a regulated 2.5 V output at up to 1.5 A. A wide input voltage range and integrated thermal and overcurrent protection enhance overall system reliability. Reference accuracy and excellent temperature characteristics are provided. An output-enable input gives the designer complete control over power up, standby, or power down. This device is supplied in a fully molded TO-220-style 5-lead flange-mounted , high power, isolated plastic package. FEATURES ■ 4.5 V to 40 V Input Range ■ 1.5 A Output Current at 2.5 V ■ 2% Output Voltage Tolerance ■ Foldback Current Limiting ■ Constant 125 kHz Switching Frequency ■ 200 µA Maximum Standby Current ■ Soft Start Prevents Supply Voltage Dip ■ Remote Voltage Sensing ■ Thermal Protection ABSOLUTE MAXIMUM RATINGS Input Voltage, VI . . . . . . . . . . . . . 43 V Output Current, IO . . . . . . . . . . . 1.5 A* Enable Input Voltage, VOE . . . . . . . . . . . 6 V Junction Temperature, TJ . . . . +125°C APPLICATIONS ■ TVs, VCRs, Electronic Games ■ Embedded Core, Memory, or Logic Supplies ■ Printers and Other Office Equipment ■ Industrial Machinery ■ Telecommunications Equipment Storage Temperature Range, TS . . . . . . . . . . . . -40°C to +125°C * Output current rating is limited by input voltage, duty cycle, and ambient temperature. Under any set of conditions, do not exceed a junction temperature of +125°C. Always order by complete part number, e.g., SI-8025JF . Sanken Power Devices from Allegro MicroSystems ih ng rs tc lato i Sw egu R SI-8025JF Step-Down to 2.5 V, 1.5 A, DC/DC Converter FUNCTIONAL BLOCK DIAGRAM Allowable Package Power Dissipation Recommended Operating Conditions DC Input Voltage (IO ≤ 1 A) (IO ≤ 1.5 A) DC Output Current (VI ≥ 6.3 V) Operating Junction Temp. Min Max Units 5.3 6.3 0 -30 6.3 40 1.5 +125 V V A °C This data sheet is based on Sanken data sheet SSJ-01952 2 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 Copyright © 2004 Allegro MicroSystems, Inc. ih ng rs tc lato i Sw egu R SI-8025JF Step-Down to 2.5 V, 1.5 A, DC/DC Converter ELECTRICAL CHARACTERISTICS at TA = +25°C, VI = 12 V, IO = 0.5 A (unless otherwise noted). Limits Characteristic Symbol Output Voltage Test Conditions Min. Typ. Max. Units VO 2.45 2.50 2.55 V Ref. Volt. Temp. Coeff. aVref — ±0.5 — mV/°C Output Short-Circuit Current IOM 1.6 — — A See note Efficiency η — 74 — % Operating Frequency f — 125 — kHz Line Regulation ∆VO(∆VI) VI = 7 V ~ 30 V, IO = 0.5 A — 25 80 mV Load Regulation ∆VO(∆IO) VI = 12 V, IO = 0.2 A ~ 0.8 A — 10 30 mV IO = 0 A — 7.0 — mA VCE = 0.3 V — — 200 µA Quiescent Current IIQ Chip Enable Voltage VCE Converter turn-off voltage — — 0.5 V Soft-Start Current ISS VSS = 0 V — — -100 µA Typical values are given for circuit design information only. Note: Output short-circuit current is at point where output voltage has decreased 5% below VO(nom). Test Circuit SI-8025JF www.allegromicro.com C1 = 220 µF/50 V C2 = 470 µF/25 V C3 = 0.47 µF/10 V L1 = 100 µH D1 = Sanken RK-16 3 ih ng rs tc lato i Sw egu R SI-8025JF Step-Down to 2.5 V, 1.5 A, DC/DC Converter TYPICAL CHARACTERISTICS (TA = 25°C) Efficiency Overcurrent Protection Low-Voltage Behavior Load Regulation Temperature Stability 4 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 ih ng rs tc lato i Sw egu R SI-8025JF Step-Down to 2.5 V, 1.5 A, DC/DC Converter APPLICATIONS INFORMATION Input Capacitor (C1). Capacitors with low impedance for high-frequency ripple current must be used. Output Capacitor (C2). Capacitors with low impedance for high-frequency ripple current must be used. Especially when the C2 impedance is high, the switching waveform may not be normal at low temperatures. Film or tantalum capacitor for C2 may cause abnormal oscillations. Catch Diode (D1). Diode D1 must be a Schottky diode. Other diode types will result in increased forward voltage spikes, reverse current flow, increased IC power dissipation during the off period, and possible destruction of the IC. Choke Coil (L1). If the winding resistance of the choke coil is too high, the circuit efficiency will decrease. As the overcurrent protection start current is approximately 2.5 A, attention must be paid to the heating of the coil by magnetic saturation due to overload. To reduce the output ripple, the inductor may be increased at the expense of excessive board area and cost. SI-8025JF www.allegromicro.com Soft-Start Capacitor (C3). Soft start for the converter is enabled by connecting a capacitor between terminal 5 and ground. The converter may be turned off by decreasing the terminal 5 voltage below 0.5 V with either an npn small-signal transistor or the output of open-collector TTL. If both a large soft-start capacitor and on/off control are desired, collector current limiting must be used to prevent transistor damage. No external voltage can be applied to terminal 5. Parallel Operation. Parallel operation to increase load current is not permitted. Overcurrent Protection. The SI-8000JF series has a built-in fold-back type overcurrent protection circuit, which limits the output current at a start-up mode. It thus cannot be used in applications that require current at the start-up mode such as: (1) constant-current load, (2) power supply with positive and negative outputs to common load (a center-tap type power supply), or (3) raising the output voltage by putting a diode or a resistor between the device ground and system ground. Typical Application 5 ih ng rs tc lato i Sw egu R SI-8025JF Step-Down to 2.5 V, 1.5 A, DC/DC Converter APPLICATIONS INFORMATION (cont.) Thermal Protection. Circuitry turns off the switching transistor when the junction temperature rises above 150°C. It is intended only to protect the device from failures due to excessive junction temperatures and should not imply that output short circuits or continuous overloads are permitted. Heat Radiation and Reliability. The reliability of the IC is directly related to the junction temperature (TJ) in its operation. Accordingly, careful consideration should be given to heat dissipation. The graph on page 2 illustrates the effect of thermal resistance on the allowable package power dissipation. When mounting to a heat sink, apply silicone grease (ShinEtsu Chemical G746, Dow Corning Toray Silicone SC102, or Toshiba Silicone SY6260). Recommended mounting hardware torque: 0.588 ~ 0.686 Nm or 6.0 ~ 7.0 kgf•cm (4.34 ~ 5.06 lbf•ft). The junction temperature (TJ) can be determined from either of the following equations: TJ = (PDRθJA) + TA or TJ = (PDRθJC) + TC where PD = VIII – VOIO – VFIO(1 – [VO/VI]) or the adjacent graph, VF = the Schottky diode forward voltage, and RθJC = 6°C/W. 6 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 Layout Guideline ih ng rs tc lato i Sw egu R SI-8025JF Step-Down to 2.5 V, 1.5 A, DC/DC Converter Dimensions in Millimeters Terminal Finish: Sn–3Ag–0.5Cu (category e1) Product Weight: Approx. 2.3 g Terminal spacing is measured at lead tips. www.allegromicro.com 7 ih ng rs tc lato i Sw egu R SI-8025JF Step-Down to 2.5 V, 1.5 A, DC/DC Converter Shipping Container Dimensions in Millimeters Primary Packing: 50 pieces per stick Product Thickness: 0.7 mm ±0.3 mm Material: Hard polyvinylchloride (transparent) Warp: Within 2 mm against L-shape dimension Secondary Packing: Ten sticks, four layers (2000 pieces per box). Cardboard box. Inner Cover Stick Stick Underlay 8 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 Shock-Absorbing Material (50-100 mm) ih ng rs tc lato i Sw egu R SI-8025JF Step-Down to 2.5 V, 1.5 A, DC/DC Converter The products described herein are manufactured in Japan by Sanken Electric Co., Ltd. for sale by Allegro MicroSystems, Inc. Sanken and Allegro reserve the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Therefore, the user is cautioned to verify that the information in this publication is current before placing any order. When using the products described herein, the applicability and suitability of such products for the intended purpose shall be reviewed at the users responsibility. Although Sanken undertakes to enhance the quality and reliability of its products, the occurrence of failure and defect of semiconductor products at a certain rate is inevitable. Users of Sanken products are requested to take, at their own risk, preventative measures including safety design of the equipment or systems against any possible injury, death, fires or damages to society due to device failure or malfunction. Sanken products listed in this publication are designed and intended for use as components in general-purpose electronic equipment or apparatus (home appliances, office equipment, telecommunication equipment, measuring equipment, etc.). Their use in any application requiring radiation hardness assurance (e.g., aerospace equipment) is not supported. When considering the use of Sanken products in applications where higher reliability is required (transportation equipment and its control systems or equipment, fire- or burglar-alarm systems, various safety devices, etc.), contact a company sales representative to discuss and obtain written confirmation of your specifications. The use of Sanken products without the written consent of Sanken in applications where extremely high reliability is required (aerospace equipment, nuclear power-control stations, life-support systems, etc.) is strictly prohibited. The information included herein is believed to be accurate and reliable. Application and operation examples described in this publication are given for reference only and Sanken and Allegro assume no responsibility for any infringement of industrial property rights, intellectual property rights, or any other rights of Sanken or Allegro or any third party that may result from its use. www.allegromicro.com 9