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SI-3120KM
1 A, Low-Dropout, 12 V Regulator
Designed to meet the high-current requirements in industrial and
consumer applications; embedded core, memory, or logic supplies; TVs,
VCRs, and office equipment, the SI-3120KM voltage regulator offers
the reduced dropout voltage and low quiescent current essential for
improved efficiency. This device delivers a regulated output at up to
1 A. Integrated thermal and overcurrent protection enhance overall
system reliability. Devices with other output voltages are also available.
Quiescent current does not increase significantly as the dropout
voltage is approached, an ideal feature in standby/resume power systems
where data integrity is crucial. Regulator accuracy and excellent
temperature characteristics are provided by a bandgap reference. An
LS-TTL/CMOS-compatible input gives the designer complete control
over power up, standby, or power down. A pnp pass element provides a
dropout voltage of less than 600 mV at 1 A of load current. Low output
voltages eliminate the need for expensive PWM buck converters. The
low dropout voltage permits more efficient regulation before output
regulation is lost.
This device is supplied in a 5-lead TO-252 style surface-mount
plastic package with ground tab to provide a low-resistance path for
maximum heat dissipation.
FEATURES
■
1 A Output Current at 12 V
■
0.6 V Maximum Dropout Voltage at I
O
= 1 A
■
Fast Transient Response
■
1 µA Maximum Standby Current
■
Remote Voltage Sensing
■
Foldback Current Limiting
■
Overvoltage Protection
■
Ground Tab for Superior Heat Dissipation
■
Thermal Protection
APPLICATIONS
■
TVs, VCRs, Electronic Games
■
Embedded Core, Memory, or Logic Supplies
■
Printers and Other Office Equipment
■
Industrial Machinery
■
Secondary-Side Stabilization of Multi-Output SMPS
Always order by complete part number, e.g.,
SI-3120KM-TL
,
where “-TL” indicates tape and reel.
Data Sheet
27468.90*
ABSOLUTE MAXIMUM RATINGS
Input Voltage, V
I
. . . . . . . . . . . . .
35 V
Output Current, I
O
. . . . . . . . . . . . .
1 A*
Enable Input Voltage, V
E
. . . . . . . . .
V
I
Junction Temperature, T
J
. . . .
+125°C
Storage Temperature Range,
T
S
. . . . . . . . . . . .
-30°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.
Sanken Power Devices
from Allegro MicroSystems
SI-3120KM
1 A, Low-Dropout,
12 V Regulator
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FUNCTIONAL BLOCK DIAGRAM
Allowable Package Power Dissipation
Recommended Operating Conditions
Min
—
0
-30
-20
Max
25
1
+100
+100
Units
V
A
°C
°C
DC Input Voltage
DC Output Current
Operating Ambient Temp.
Operating Junction Temp.
For the availability of parts meeting -40°C requirements,
contact Allegro’s Sales Representative.
This data sheet is based on Sanken data sheet SSJ-02039
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Copyright © 2004, 2005 Allegro MicroSystems, Inc.
2
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TYPICAL CHARACTERISTICS (cont.)
(V
I
= 14 V, T
A
= 25°C)
SI-3120KM
1 A, Low-Dropout,
12 V Regulator
Overvoltage Protection
GND Pin Current
APPLICATIONS INFORMATION
Input Capacitor
(C
I
,
≥22
µF). This is necessary either
when the input line includes inductance or when the wiring
is long.
Output Capacitor
(C
O
,
≥47
µF). This device is not
designed for a use with a very low ESR output capacitor
such as a ceramic capacitor. Output oscillation may occur
with that kind of capacitor. The recommended ESR is
0.2~2
Ω
at T
A
= 25°C.
Reverse-Bias Protection Diode
(D1). Diode D1
provides reverse-bias protection between the input and
output. Sanken type SFPL-52 is recommended.
ENABLE Input.
The ENABLE (control) input features
an internal pull-down resistor. Leaving this input open
causes the output to turn off.
Parallel Operation.
Parallel operation to increase load
current is not permitted.
Increased Output Voltage.
The output voltage (V
O
)
may be increased by inserting a resistor (R
EXT
) between
SENSE and OUTPUT. The current flowing into SENSE is
typically 90 µA ±30%. To minimize the effect of I
SENSE
and temperature on R
EXT
, it is recommended that a 24 kΩ
resistor be added between SENSE and GND to increase the
current in R
EXT
. The value of R
EXT
is then
6
R
EXT
= (V
O
– 12) × 10 /600
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