SPI-8010A - Allegro MicroSystems, Inc.

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 µA 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, VI. . . . . . . . . . . . . 53 V

Output Current, IO. . . . . . . . . . . . . 3 A*

Junction Temperature, TJ. . . . +125°C

Storage Temperature Range,

TS. . . . . . . . . . . . -40°C to +125°C

* 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 +125°C.

SPI

-8010

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

FUNCTIONAL BLOCK DIAGRAM

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, VO + 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

ELECTRICAL CHARACTERISTICS at TA = +25°C, VI = 12 V, IO = 1 A (unless otherwise noted).

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Internal Reference Voltage Vref 0.97 1.00 1.03 V

Ref. Volt. Temp. Coeff. aVref — ±0.5 — mV/°C

Output Short-Circuit Current IOM See note 3.1 — — A

Efficiency ηVI = 20 V, VO = 5 V, IO = 1 A — 86 — %

Operating Frequency f — 250 — kHz

Overvoltage Protection VIM IO = 10 mA 33 — — V

Line Regulation ∆VO(∆VI) VI = 10 V ~ 30 V — 20 40 mV

Load Regulation ∆VO(∆IO) IO = 0.1 A ~ 1.5 A — 10 30 mV

Quiescent Current IIQ IO = 0 A — 7.0 — m A

VOE/SS = 0.3 V — — 400 µ A

Chip Enable Voltage VOE/SS Device turn-off voltage — — 0.5 V

Soft-Start Current IOE/SS VOE/SS = 0 V — — -50 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

SPI-8010A

3 A, DC/DC

Step-Down Converter

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036

Switching

Regulators

TYPICAL CHARACTERISTICS

(VI = 12 V, TA = 25°C)

 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

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 Ω for

R3 is recommended.

R2 = (VO – Vref)/(Vref/R3)

C1 220 µF/63 V

C2 470 µF/25 V

C3 0.1 µF

C4 1000 pF

C5 0.1 µF

C6 0.047 µF

C7 0.1 µF

C8 0.1 µF

C9 6800 pF

R1 47 Ω

L1 47 µH

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, VO + 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

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 170°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 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 (RθJA).

The junction temperature (TJ) can be determined from

either of the following equations:

TJ = (PDRθJA) + TA

or TJ = (PDRθJL) + TL

where PD = VIII – VOIO – VFIO(1 – [VO/VI]),

VF = the Schottky diode forward voltage, and

RθJL = 18°C/W.

Layout Guideline

SPI-8010A

3 A, DC/DC

Step-Down Converter

www.allegromicro.com

Switching

Regulators

Dimensions in Millimeters

Lead Temperature

(TL) 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

Tape and Reel Dimensions in Millimeters

SPI-8010A

3 A, DC/DC

Step-Down Converter

www.allegromicro.com

Switching

Regulators

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 pr oducts described her ein, the applicability and

suitability of such pr oducts for the intended purpose shall be r eviewed at

the users responsibility .

Although Sanken undertakes to enhance the quality and reliability of

its pr oducts, the occurr ence of failur e and defect of semiconductor

pr oducts at a certain rate is inevitable.

Users of Sanken pr oducts ar e r equested to take, at their own risk,

pr eventative measur es including safety design of the equipment or

systems against any possible injury , death, fir es or damages to society

due to device failure or malfunction.

Sanken pr oducts listed in this publication are designed and intended

for use as components in general-purpose electr onic equipment or

apparatus (home appliances, office equipment, telecommunication

equipment, measuring equipment, etc.). Their use in any application

r equiring radiation har dness assurance (e.g., aerospace equipment) is

not supported.

When considering the use of Sanken pr oducts in applications wher e

higher r eliability is r equired (transportation equipment and its contr ol

systems or equipment, fir e- or burglar-alarm systems, various safety

devices, etc.), contact a company sales r epresentative to discuss and

obtain written confirmation of your specifications.

The use of Sanken pr oducts without the written consent of Sanken in

applications wher e extremely high r eliability is requir ed (aer ospace

equipment, nuclear power-contr ol stations, life-support systems, etc.) is

strictly pr ohibited.

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.

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