SPI-8002TW-TL - Allegro MicroSystems Europe Ltd.

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 fre-

quency 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

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 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

Dual 1.5 A, DC/DC Step-Down Converter

Data Sheet

27469.302.1

Always order by complete part number, e.g., SPI-8002TW-TL ,

where “-TL” indicates tape and reel.

ABSOLUTE MAXIMUM RATINGS

Input Voltage, VI, VCC, VCE . . . . . 40 V

Output Current, IO. . . . . . . . . . . 1.5 A*

Junction Temperature, TJ. . . . +135°C

Storage Temperature Range,

TS. . . . . . . . . . . . -40°C to +135°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 +135°C.

SPI

-8002

Sanken Power Devices

from Allegro MicroSystems

Switching

Regulators

SPI-8002

Dual 1.5 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, VI *V

O + 3 38 V

DC Input Voltage, VCC 4.5 38 V

DC Output Current, IO0 1.5 A

DC Output Voltage, VO124V

Operating Junction Temp. -30 +135 °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 -40°C require-

ments, contact Allegro’s Sales Representative.

Allowable Package Power Dissipation

This data sheet is based on Sanken data sheet SSJ-02285

SPI-8002

Dual 1.5 A, DC/DC

Step-Down Converter

www.allegromicro.com

Switching

Regulators

ELECTRICAL CHARACTERISTICS at TA = +25°C, VI = VCC = 15 V (unless otherwise noted).

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Internal Reference Voltage Vref VI = 10 V, VO = 1 V, IO = 0.1 A 0.996 1.006 1.016 V

Ref. Volt. Temp. Coeff. aVref VI = 10 V, VO = 1 V, IO = 0.1 A — ±0.1 — mV/°C

Output Short-Circuit Current IOM See note 1.6 — — A

Efficiency ηVO = 5 V, IO = 0.5 A, II includes ICC —78— %

VCC = 5 V, VO = 5 V, IO = 0.5 A, — 81 — %

II does not include ICC

Operating Frequency f VO = 5 V, IO = 0.5 A 215 250 285 kHz

Line Regulation ∆VO(∆VI) VI = VCC = 10 V ~ 20 V, VO = 5 V, IO = 1 A — 30 60 m V

Load Regulation ∆VO(∆IO) VO = 5 V, IO = 0.2 A ~ 1.5 A — 10 40 m V

Supply Current ICC IO = 0 A — 8.5 — m A

Quiescent Current IIQ VCC = 5 V, IO = 0 A, VO ≤ 12 V — 4.0 — m A

VCE = 0 V or open — — 1.0 µA

ICCQ VCE = 0 V or open — — 1.0 µA

Chip Enable Voltage VCEH 2.0 — — V

VCEL — — 0.8 V

Chip Enable Input Current ICE VCE = 20 V — 95 — µ A

Soft-Start Voltage VSS Converter turn-off voltage — — 0.5 V

Soft-Start Current ISS VSS = 0 V — -60 -80 µ 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 VO(nom).

Test Circuit

SPI-8002

Dual 1.5 A, DC/DC

Step-Down Converter

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036

Switching

Regulators

TYPICAL CHARACTERISTICS

(TA = 25°C)

 Efficiency  Efficiency

 Load Regulation

 Low-Voltage Behavior

 Load Regulation

SPI-8002

Dual 1.5 A, DC/DC

Step-Down Converter

www.allegromicro.com

Switching

Regulators

TYPICAL CHARACTERISTICS (cont.)

(TA = 25°C)

 Overcurrent Protection

 Soft-Start Current

 Temperature Stability

 Chip Enable Control Voltage

 Overcurrent Protection

SPI-8002

Dual 1.5 A, DC/DC

Step-Down Converter

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036

Switching

Regulators

APPLICATIONS INFORMATION

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 de-

crease. 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.

Output Voltage Adjustable Resistors (R1, R2, R3,

and R4). The output voltages are adjusted by R1 and R3.

1000 Ω 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 transis-

tor 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.

C1 220 µF/63 V

C2, C3 470 µF/25 V

C4, C5 1 µ F

C6, C7, C8 0.1 µF

R5, R6 1 kΩ

L1, L2 47 µH

D1, D2 Sanken SFPB-66

Typical Application

SPI-8002

Dual 1.5 A, DC/DC

Step-Down Converter

www.allegromicro.com

Switching

Regulators

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.

Layout Guideline

Parallel Operation. Parallel operation to increase load

current is not permitted.

Thermal Protection. Circuitry turns off the device

when the junction temperature rises above 135°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 = (PD × RθJA) + TA

or TJ = (PD × RθJL) + TL

where

RθJL = 9°C/W

and

100

ηx

=‰I

O‰

–––

where VO is the output voltage, VIN is the input voltage, IO

is the output current ηx is efficiency (%) and VF is the

diode forward voltage SFPB-66 (0.45 V, IO= 1A).

SPI-8002

Dual 1.5 A, DC/DC

Step-Down Converter

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036

Switching

Regulators

Dimensions in Millimeters

Lead Temperature

(TL) Measured at

Terminal 1 or 9

View A

Product Weight: Approx. 0.859 g

Recommended Land Pattern

SPI-8002

Dual 1.5 A, DC/DC

Step-Down Converter

www.allegromicro.com

Switching

Regulators

Tape and Reel Dimensions in Millimeters

EI17EI

SPI-8002

Dual 1.5 A, DC/DC

Step-Down Converter

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036

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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