Data Sheet
27468.25*
LOW-VOLTAGE, HIGH-CURRENT
2.5 V LINEAR REGULATOR
The SI-3025LSA is designed to meet the requirement for increased
integration and reliability in low-voltage, high-current, linear regulator
applications such as personal computers (PCs) and set-top boxes. Each
device incorporates a monolithic low-level reference and control circuit
with a high-current pnp transistor in a power multi-chip module
(PMCM™). Regulated output voltages of 1.8 V or 3.3 V are also
available.
The high-current pass element provides a low dropout voltage with
output current to 1 A. Regulator accuracy of ±2 % and excellent
temperature characteristics are provided. The logic-compatible
ENABLE input gives the designer complete control over power up,
power down, and standby or sleep.
These devices are supplied in a fully molded 8-lead miniature
surface-mount package (tape and reel) with enhanced power-dissipating
qualities. They are rated for continuous operation between -30°C and
+100°C.
FEATURES
■1 A Output Current
■Low Dropout voltage
■LSTTL/CMOS-Compatible On/Off Control
Less Than 1 µA “Sleep” Current
■Internal Foldback Overcurrent Limiting
■Internal Thermal Shutdown
■Surface-Mount Package
Always order by complete part number: SI-3025LSA-TL ,
where “-TL” indicates tape and reel.
ABSOLUTE MAXIMUM RATINGS
Input Voltage, VI................................ 16 V
Supply Voltage, VS............................ 16 V
Continuous Output Current, IO........ 1.0 A*
Logic Input Voltage, VE......................... VS
Package Power Dissipation,
PD........................................ See Graph
Output Junction Temperature,
TJ............................................ +150°C†
Operating Temperature Range,
TA............................... -30°C to +100°C
Storage Temperature Range,
Tstg ............................. -30°C to +150°C
* Output current rating may be limited by duty
cycle, ambient temperature, and heat sinking.
Under any set of conditions, do not exceed the
specified current rating or a junction temperature
of 150˚C.
† Fault conditions that produce excessive
junction temperature will activate the device’s
thermal shutdown circuitry. These conditions
can be tolerated but should be avoided.
SI-3025LSA
1
2
3
45
6
7
8
Dwg. PK-012
IN
GND
OUT
INTERNAL
CONNECTION
ENABLE
SUPPLY GND
OUT
IC VR SUB
V
S
TM
Linear
Regulators
Sanken Power Devices
from Allegro MicroSystems
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
SI-3025LSA
LOW-VOLTAGE, HIGH-CURRENT
2.5 V LINEAR REGULATOR
TM
2
FUNCTIONAL BLOCK DIAGRAM
Copyright © 2001, 2005 Allegro MicroSystems, Inc.
1.5
1.0
0.5
20 60 10040
0
AMBIENT TEMPERATURE in °°
°°C
ALLOWABLE PACKAGE POWER DISSIPATION in WATTS
Dwg. GK-010-1
80 1200
56.5 mm x 56.5 mm
COPPER AREA ON
GLASS-EPOXY BOARD
140
28 mm x 28 mm
COPPER AREA ON
GLASS-EPOXY BOARD
40 mm x 40 mm
COPPER AREA ON
GLASS-EPOXY BOARD
20 mm x 20 mm
COPPER AREA ON
GLASS-EPOXY BOARD
Leads 7 and 8 are soldered to the
copper area and provide heat
sinking of the pass transistor.
RECOMMENDED OPERATING CONDITIONS
Max. Input Voltage, VI................................................ 3.5 V
Output Current, IO.......................................... 0 A to 1.0 A
Output Junction Temperature Range, TJ -20 °C to +125°C
Ambient Temperature Range, TA.............. -30°C to +85°C
For the availability of parts meeting -40°C requirements,
contact Allegro’s Sales Representative.
This data sheet is based on Sanken data sheet SSJ-01776.
INPUT
1
SUPPLY 3OUTPUT
OUTPUT
8
7
6
Dwg. FK-019
GROUNDGROUND 5
4
2
ENABLE
INTERNAL
CONNECTION
SUB
+
THERMAL
PROTECTION
SI-3025LSA
LOW-VOLTAGE, HIGH-CURRENT
2.5 V LINEAR REGULATOR
www.allegromicro.com
3
ELECTRICAL CHARACTERISTICS at TA = +25°C, VI = VS = 3.3 V, VE = 2.0 V (unless otherwise
noted).
Limits
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Output Voltage VOIO = 500 mA 2.45 2.50 2.55 V
VOQ VE = 0 V, Output Off — — 0.5 V
Output Volt. Temp. Coeff. aVO IO = 5 mA, 0°C ≤ TJ ≤ 100°C—±0.3 — mV/°C
Overcurrent Limit IOM VO = 95% of VO at IO = 500 mA 1.2 1.5 — A
Line Regulation ∆VO(∆VI) 3.1 V ≤ VI = VS ≤ 3.5 V, IO = 300 mA — 2.0 10 mV
Load Regulation ∆VO(∆IO) 0 ≤ IO ≤ 1 A — 10 20 mV
Dropout Voltage VImin - VOIO ≤ 0.5 A — 220 400 mV
IO ≤1 A — 350 800 mV
Ground Terminal Current IGND IO = 0 mA — 1.7 2.5 mA
IQVE = 0 V, IO = 0 mA — — 1.0 µA
Rejection Ratio PSRR 100 Hz ≤ f ≤ 120 Hz — 57 — dB
ENABLE Input Voltage VEH Output On 2.0 — — V
VEL Output Off — — 0.8 V
ENABLE Input Current IEH VE = 2 V, Output On — 40 80 µA
IEL VE = 0 V, Output Off — 0 -5.0 µA
Thermal Shutdown Temp. TJ135 150 — °C
Thermal Resistance RθJL To terminals 7 and 8 — 36 — °C/W
Typical values are at TA = +25°C and are given for circuit design information only.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
SI-3025LSA
LOW-VOLTAGE, HIGH-CURRENT
2.5 V LINEAR REGULATOR
TM
4
TYPICAL CHARACTERISTICS at TA = 25°C
0.2
0.1
0
0.3
0.4
0.5
0.4 0.8
OUTPUT CURRENT in AMPERES
0
Dwg. GK-025-1
DROPOUT VOLTAGE
1.20.6 1.00.2
0.6
2.50
2.48
2.46
2.52
2.54
2.56
0.4 0.8
OUTPUT CURRENT in AMPERES
0
Dwg. GK-026-1
OUTPUT VOLTAGE
1.20.6 1.00.2
2.58
V
I
= V
S
= 10 V
V
I
= V
S
= 8 V
V
I
= V
S
= 5 V
V
I
= V
S
= 3.2 V
0
1.0
2.0
OUTPUT CURRENT in AMPERES
0
Dwg. GK-027-1
OUTPUT VOLTAGE
2.01.0 1.50.5
3.0
V
I
= V
S
= 3.2 V
V
I
= V
S
= 5 V
V
I
= V
S
= 6 V
INPUT VOLTAGE
0
Dwg. GK-028-1
OUTPUT VOLTAGE
5.03.0 4.01.0 2.0
I
O
= 0 A
I
O
= 0.5 A
I
O
= 1 A
0
1.0
2.0
3.0
Dropout voltage Load regulation
Overcurrent protection VOUT vs VIN
SI-3025LSA
LOW-VOLTAGE, HIGH-CURRENT
2.5 V LINEAR REGULATOR
www.allegromicro.com
5
TYPICAL CHARACTERISTICS at TA = 25°C (cont’d)
2.50
2.48
2.46
2.52
2.54
2.56
4.0 8.0
INPUT VOLTAGE
0
Dwg. GK-029-1
OUTPUT VOLTAGE
126.0 102.0
2.58
I
O
= 1 A
I
O
= 0.5 A
I
O
= 0 A
0
5.0
10
15
4.0 8.0
INPUT VOLTAGE
0
Dwg. GK-030-1
GROUND CURRENT in mA
126.0 102.0
20
I
O
= 1 A
I
O
= 0.5 A
I
O
= 0 A
20
10
0
30
40
50
1.0 2.0
ENABLE VOLTAGE in VOLTS
0
Dwg. GK-023
ENABLE INPUT CURRENT in µµ
µµA
3.0
VI = VS = 3.3 V
IO = 5 mA
1.5 2.50.5
60
Line regulation GND current
ENABLE input current
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
SI-3025LSA
LOW-VOLTAGE, HIGH-CURRENT
2.5 V LINEAR REGULATOR
TM
6
APPLICATIONS INFORMATION
Thermal shutdown and heat sinking. Thermal protection
circuitry turns off the device should the junction temperature rise
above 135°C. This is intended only to protect the device from
failures due to excessive junction temperatures and should not
imply that high-temperature operation is permitted. Ambient
temperature is affected by air circulation and proximity to other
heat-producing components. Normal operation is resumed when
the junction temperature is reduced. Output terminals 7 and 8
are the lead frame and substrate of the pass transistor and
provide a low thermal-resistance path for heat sinking.
In general, the maximum ambient temperature has the most
effect on determining the heat sinking that is needed to maintain
a safe normal operating junction temperature. The maximum
heat sinking thermal resistance (RθJA) can be calculated as
RθJA = (135 – TA) / IO (VI – 2.5)
where TA is the maximum ambient temperature in °C,
IO is the maximum output (load) current in amperes, and
VI is the maximum input voltage in volts.
The following graph gives the required copper foil area
(soldered to leads 7 and 8) to provide the required thermal
resistance. Note that more is always better and both sides of the
printed wiring board can be used.
ENABLE input. The ENABLE input includes an internal pull-
100
200
300
500
JUNCTION-TO-AMBIENT THERMAL RESISTANCE in °°
°°C/W
90
Dwg. GK-031
FOIL AREA in SQ. mm
130110 120100
1000
2000
GLASS-EPOXY
PRINTED WIRING BOARD
down resistor. If this terminal is not connected (open-circuit
fault), the device output is turned off.
Overcurrent protection. The SI-3025LSA includes an
overcurrent protection circuit, which limits the output current at
start up. It thus cannot be used with
1) a constant-current load,
2) a power supply with positive and negative to a common load
(center-tap type power supply),
3) a series power supply, or
4) a diode or resistor in series with the device ground to raise
the output voltage.
Input voltage. Including ripple voltage and transients, the
minimum input voltage should be greater than the sum of the
output voltage and the maximum rated dropout voltage; the
maximum input voltage must be less than the absolute maximum
rated input voltage (16 V).
In most applications, the input voltage (terminal 1, VI) and
the supply voltage (terminal 3, VS) are connected together.
Output capacitor. A 22 µF tantalum electrolytic capacitor is
recommended between the output and ground. Very-low ESR
capacitors should not be used.
Input capacitor. A 0.1 µF to 10 µF tantalum capacitor is
recommended between the input and ground to prevent oscilla-
tion.
SI-3025LSA
LOW-VOLTAGE, HIGH-CURRENT
2.5 V LINEAR REGULATOR
www.allegromicro.com
7
NOTES: 1. Exact body and lead configuration at vendor’s option within limits shown.
2. Lead spacing tolerance is non-cumulative.
3. Leads 7 and 8 are internally connected together and provide heat sinking of the pass transistor.
0° TO 10°
5.1
±0.4
6.2
±0.3 0.5
±0.1
Dwg. MK-006-8 mm
1.27
BSC
0.25
0.10
8
1
4.4
±0.2
0.4
±0.1
1.55
±0.15
0.10 MAX.
576
Dimensions in Millimeters
(controlling dimensions)
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
SI-3025LSA
LOW-VOLTAGE, HIGH-CURRENT
2.5 V LINEAR REGULATOR
TM
8
Tape and Reel Dimensions in Millimeters
(controlling dimensions)
12.0
10.25
5.5
5.6
0.7
8.0
4.0
2.0
1.55
2.0
CENTER LINES
OF CAVITY
COVER TAPE
Dwg. MA-015-1
2.5
0.3
USER DIRECTION OF UNREELING
2.0
180 13 ± 0.2 60
Dwg. MA-018-1
(MEASURED AT HUB
TAPE SLOT
IN CORE
FOR TAPE
START
ACCESS
HOLE
13.0 ± 0.3
(MEASURED AT HUB
15.4 ± 1.0
SI-3025LSA
LOW-VOLTAGE, HIGH-CURRENT
2.5 V LINEAR REGULATOR
www.allegromicro.com
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 suitabil-
ity 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 Sanken 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 publication 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.
EI18EI
