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-8010A dc/dc step- down (buck) converter offers a constant 250 khz switching frequency essential for small external components. the n-channel high-current 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 wide 8 v to 50 v input range adjustable 1.2 v to 16 v output range 3% output voltage tolerance to 3 a output current foldback current limiting constant 250 khz switching frequency 400 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 3 a, dc/dc step-down converter data sheet 27469.1 always order by complete part number, e.g., SPI-8010A-tl , where ?-tl? indicates tape and reel. absolute maximum ratings input voltage, v i . . . . . . . . . . . . . 53 v output current, i o . . . . . . . . . . . . . 3 a* junction temperature, t j . . . . +125c storage temperature range, t s . . . . . . . . . . . . -40c to +125c * output current rating is limited by input voltage, duty cycle, and ambient tempera- ture. under any set of conditions, do not exceed a junction temperature of +125c. spi -8010 a sanken power devices from allegro microsystems switching regulators
SPI-8010A 3 a, dc/dc step-down converter 115 northeast cutoff, box 15036 worcester, massachusetts 01615-0036 switching regulators 2 functional block diagram copyright ? 2004 allegro microsystems, inc. recommended operating conditions min max units dc input voltage* 8 50 v dc output current 0.02 3 a adjustable voltage range 1.2 16 v operating junction temp. -30 +125 c *the minimum value of dc input voltage is 8 v when the output is less than 5 v, v o + 3 v when the output voltage is more than 5 v. the recommended maximum value is 50 v when the output value is more than 2.5 v, derated linearly to 30 v when the output is 1 v. allowable package power dissipation this data sheet is based on sanken data sheet ssj-02095
SPI-8010A 3 a, dc/dc step-down converter www.allegromicro.com switching regulators 3 electrical characteristics at t a = +25c, v i = 12 v, i o = 1 a (unless otherwise noted). limits characteristic symbol test conditions min. typ. max. units internal reference voltage v ref 0.97 1.00 1.03 v ref. volt. temp. coeff. a vref ? 0.5 ? mv/c output short-circuit current i om see note 3.1 ? ? a efficiency v i = 20 v, v o = 5 v, i o = 1 a ? 86 ? % operating frequency f ? 250 ? khz overvoltage protection v im i o = 10 ma 33 ? ? v line regulation ? v o( ? vi) v i = 10 v ~ 30 v ? 20 40 mv load regulation ? v o( ? io) i o = 0.1 a ~ 1.5 a ? 10 30 mv quiescent current i iq i o = 0 a ? 7.0 ? ma v oe/ss = 0.3 v ? ? 400 a chip enable voltage v oe/ss device turn-off voltage ? ? 0.5 v soft-start current i oe/ss v oe/ss = 0 v ? ? -50 a typical values are given for circuit design information only. note: output short-circuit current is at point where output voltage has decreased 5% below v o(nom) . test circuit
SPI-8010A 3 a, dc/dc step-down converter 115 northeast cutoff, box 15036 worcester, massachusetts 01615-0036 switching regulators 4 typical characteristics (v i = 12 v, t a = 25c) efficiency temperature characteristics rise characteristic load regulation overcurrent protection thermal protection
SPI-8010A 3 a, dc/dc step-down converter www.allegromicro.com switching regulators 5 applications information input capacitor (c1 and c7). capacitors with low impedance for high-frequency ripple current must be used. output capacitor (c2 and c8). 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 capacitors for c2 may cause abnormal oscilla- tions. 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 dissipa- tion 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 4.5 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. output voltage adjustable resistors (r2 and r3). the output voltage is adjusted by r2 and r3. 500 ? for r3 is recommended. r2 = (v o ? v ref )/(v ref /r3) c1 220 f/63 v c2 470 f/25 v c3 0.1 f c4 1000 pf c5 0.1 f c6 0.047 f c7 0.1 f c8 0.1 f c9 6800 pf r1 47 ? l1 47 h d1 sanken spb-g56s determination of dc input voltage. the minimum value of dc input voltage is 8 v when the output is less than 5 v, v o + 3 v when the output voltage is more than 5 v. the recommended maximum value is 50 v when the output value is more than 2.5 v, derated linearly to 30 v when the output is 1 v. typical application
SPI-8010A 3 a, dc/dc step-down converter 115 northeast cutoff, box 15036 worcester, massachusetts 01615-0036 switching regulators 6 applications information (cont.) soft-start capcitor (c4). soft start is enabled by connecting a capacitor between terminal 4 and ground. the device may be turned off (chip enable) by decreasing the terminal 4 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 chip on/off control are desired, collector current limiting must be used to prevent transistor damage. no external voltage can be applied to terminal 4. overcurrent protection. the spi-8000a 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. parallel operation. parallel operation to increase load current is not permitted. thermal protection. circuitry turns off the device when the junction temperature rises above 170c. 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 (t j ) 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 (r ja ). the junction temperature (t j ) can be determined from either of the following equations: t j = (p d r ja ) + t a or t j = (p d r jl ) + t l where p d = v i i i ? v o i o ? v f i o (1 ? [v o /v i ]), v f = the schottky diode forward voltage, and r jl = 18c/w. layout guideline
SPI-8010A 3 a, dc/dc step-down converter www.allegromicro.com switching regulators 7 dimensions in millimeters lead temperature (t l ) measured at terminal 3 view a product weight: approx. 0.859 g recommended land pattern
SPI-8010A 3 a, dc/dc step-down converter 115 northeast cutoff, box 15036 worcester, massachusetts 01615-0036 switching regulators 8 tape and reel dimensions in millimeters
SPI-8010A 3 a, dc/dc step-down converter www.allegromicro.com switching regulators 9 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 publica- tion 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. inner box outer box
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