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 24 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-8010A
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, 2005 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
24
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.
For the availability of parts meeting -40C require-
ments, contact Allegro's Sales Representative.
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
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