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Data Sheet 27469.302.1
SPI-8002TW
Dual 1.5 A, DC/DC Step-Down 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 equipment, the SPI-8002TW dc/dc step-down (buck) converter offers a constant 250 kHz switching frequency essential for small external components. The n-channel highcurrent FET is included on the die along with the oscillator, control, and logic circuitry. A wide input voltage range and integrated thermal and overcurrent protection enhance overall system reliability. Reference accuracy and excellent temperature characteristics are provided. A chip-enable input gives the designer complete control over power up, standby, or power down. This device is supplied in a 16-lead surface-mount plastic SOIC with exposed pad to provide a low-resistance path for maximum power dissipation, low junction temperature, and improved reliability. FEATURES To 38 V Input Range Adjustable 1 V to 24 V Output Range 1% Output Voltage Tolerance To 1.5 A Output Current Foldback Current Limiting Constant 250 kHz Switching Frequency 1.0 A Maximum Standby Current 1.0 V Feedback Reference Voltage Soft Start Avoids Supply Voltage Dip Remote Voltage Sensing Exposed Pad for Superior Heat Dissipation Thermal Protection APPLICATIONS TVs, VCRs, Electronic Games Embedded Core, Memory, or Logic Supplies Printers and Other Office Equipment Industrial Machinery
ABSOLUTE MAXIMUM RATINGS
Input Voltage, VI, VCC, VCE . . . . . 40 V
Output Current, IO . . . . . . . . . . . 1.5 A* Junction Temperature, TJ . . . . +135C Storage Temperature Range, TS . . . . . . . . . . . . -40C to +135C * 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 +135C.
Always order by complete part number, e.g., SPI-8002TW-TL , where "-TL" indicates tape and reel.
Sanken Power Devices from Allegro MicroSystems
SPI-8002TW Dual 1.5 A, DC/DC Step-Down Converter
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FUNCTIONAL BLOCK DIAGRAM
Allowable Package Power Dissipation
Recommended Operating Conditions
Min DC Input Voltage, VI * DC Input Voltage, VCC DC Output Current, IO DC Output Voltage, VO Operating Junction Temp. VO + 3 4.5 0 1 -30 Max 38 38 1.5 24 +135 Units V V A V C
*The recommended maximum value is 38 V when the output value is more than 4.75 V, derated linearly to 8 V when the output is 1 V. For the availability of parts meeting -40C requirements, contact Allegro's Sales Representative.
This data sheet is based on Sanken data sheet SSJ-02285
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 Copyright (c) 2004, 2005 Allegro MicroSystems, Inc.
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SPI-8002TW Dual 1.5 A, DC/DC Step-Down Converter
ELECTRICAL CHARACTERISTICS at TA = +25C, VI = VCC = 15 V (unless otherwise noted).
Limits Characteristic Internal Reference Voltage Ref. Volt. Temp. Coeff. Output Short-Circuit Current Efficiency Symbol Vref Test Conditions VI = 10 V, VO = 1 V, IO = 0.1 A VI = 10 V, VO = 1 V, IO = 0.1 A See note VO = 5 V, IO = 0.5 A, II includes ICC VCC = 5 V, VO = 5 V, IO = 0.5 A, II does not include ICC Operating Frequency Line Regulation Load Regulation Supply Current Quiescent Current f VO(VI) VO(IO) ICC IIQ ICCQ Chip Enable Voltage VCEH VCEL Chip Enable Input Current Soft-Start Voltage Soft-Start Current ICE VSS ISS VCE = 20 V Converter turn-off voltage VSS = 0 V VO = 5 V, IO = 0.5 A VI = VCC = 10 V ~ 20 V, VO = 5 V, IO = 1 A VO = 5 V, IO = 0.2 A ~ 1.5 A IO = 0 A VCC = 5 V, IO = 0 A, VO 12 V VCE = 0 V or open VCE = 0 V or open Min. 0.996 -- 1.6 -- -- 215 -- -- -- -- -- -- 2.0 -- -- -- -- Typ. Max. Units V mV/C A % % kHz mV mV mA mA A A V V A V A
1.006 1.016 0.1 -- 78 81 250 30 10 8.5 4.0 -- -- -- -- 95 -- -60 -- -- -- -- 285 60 40 -- -- 1.0 1.0 -- 0.8 -- 0.5 -80
aVref
IOM
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
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SPI-8002TW Dual 1.5 A, DC/DC Step-Down Converter
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TYPICAL CHARACTERISTICS
(TA = 25C)
Efficiency
Efficiency
Low-Voltage Behavior
Load Regulation
Load Regulation
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115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036
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TYPICAL CHARACTERISTICS (cont.)
(TA = 25C) Overcurrent Protection
SPI-8002TW Dual 1.5 A, DC/DC Step-Down Converter
Overcurrent Protection
Temperature Stability
Soft-Start Current
Chip Enable Control Voltage
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SPI-8002TW Dual 1.5 A, DC/DC Step-Down Converter
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APPLICATIONS INFORMATION
Output Voltage Adjustable Resistors (R1, R2, R3, and R4). The output voltages are adjusted by R1 and R3. 1000 for R2 and R4 is recommended. R1 = (VO1 - Vref)/(Vref/R2) R3 = (VO2 - Vref)/(Vref/R4) Soft-Start Capcitors (C4 and C5). Soft start for each converter channel is enabled by connecting a capacitor between terminal 6 and/or 11 and ground. The channel may be turned off by decreasing the terminal 6 and/or 11 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 (R5 and R6) must be used to prevent transistor damage. No external voltage can be applied to terminal 6 or 11.
Input Capacitors (C1 and C6). Capacitors with low impedance for high-frequency ripple current must be used. Output Capacitors (C2, C3, C7, and C8). Capacitors with low impedance for high-frequency ripple current must be used. Especially when the C2 and C3 impedance is high, the switching waveform may not be normal at low temperatures. Film or tantalum capacitors for C2 and C3 may cause abnormal oscillations. Catch Diodes (D1 and D2). Diode D1 and D2 must be Schottky diodes. 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 Coils (L1 and L2). 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 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.
Typical Application
C1 C2, C3 C4, C5 C6, C7, C8 R5, R6 L1, L2 D1, D2
220 F/63 V 470 F/25 V 1 F 0.1 F 1 k 47 H Sanken SFPB-66
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115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036
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APPLICATIONS INFORMATION (cont.)
Overcurrent Protection. The SPI-8000TW 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. Determination of DC Input Voltage. The minimum value of dc input voltage is VO + 3 V. The recommended maximum value is 38 V when the output value is more than 4.75 V, derated linearly to 8 V when the output is 1 V.
SPI-8002TW Dual 1.5 A, DC/DC Step-Down Converter
Layout Guideline
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 inner frame on which the integrated circuit is mounted is connected to the exposed pad. Therefore, it is very effective for heat radiation to enlarge the copper area that is connected to the pad. The graph on page 2 illustrates the effect of the copper area on the junction-to-ambient thermal resistance (RJA). The junction temperature (TJ) can be determined from either of the following equations: Parallel Operation. Parallel operation to increase load current is not permitted. Thermal Protection. Circuitry turns off the device when the junction temperature rises above 135C. 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. or where and TJ = (PD x RJA) + TA TJ = (PD x RJL) + TL RJL = 9C/W
PD =
VO
IO
100 - 1 - VF x
IO 1 -
VIN
VO
where VO is the output voltage, VIN is the input voltage, IO is the output current x is efficiency (%) and VF is the diode forward voltage SFPB-66 (0.45 V, IO= 1A). .
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SPI-8002TW Dual 1.5 A, DC/DC Step-Down Converter
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Dimensions in Millimeters
Lead Temperature (TL) Measured at Terminal 1 or 9
View A
Recommended Land Pattern
Product Weight: Approx. 0.859 g
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115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036
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SPI-8002TW Dual 1.5 A, DC/DC Step-Down Converter
Tape and Reel Dimensions in Millimeters
EI17EI www.allegromicro.com
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SPI-8002TW Dual 1.5 A, DC/DC Step-Down Converter
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Inner Box
Outer Box
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.
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115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036

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