Bay Linear LM3940T, LM3940S, LM3940N, LM3940J Datasheet
Bay Linear
Inspire the Linear Power
1.25A High Current Low Dropout
Voltage Regulator for Convert 5V & 3.3V
Description
The Bay Linear LM3940 is a 1.25A high accuracy, low dropout
voltage regulator with only 40mV at light loads and
350mV(Typ.)@ 1.0A) and low quiescent current of 240µA typical.
The LM3940 is designed for low voltage a application that requires
lower dropout voltage and faster transient response. This device is
an excellent choice for use in powering low voltage applications
where require a lower dropout, faster transient response to regulate
from +2.5V to 3.8V supplies and as a post regulator for switching
supplies applications.
The LM3940 offers full protection against over-current faults,
reversed input polarity, reversed load insertion, and positive and
negative transient voltage. On-Chip trimming adjusts the reference
voltage to 1%.
The LM3940 are offered in a 3-pin SOT-223, TO-220 & TO-263
package compatible with other 3 terminal regulators. The LM3940
is also offer in a new LPDD (Low Profile TO-263) package from
4.47 mm (DD) tickness down to only 1.27 mm (LPDD) total
tickness.
Pin Connection
LM3940
Features
• High output accuracy of 1%
• Fix Output 5.0v & 3.3V
• Output Current of 1.25A
• Low Dropout Voltage
• Low quiescent current
• Extremely Tight Load & Line Regulation
• Reverse-battery and “Load Dump” Protection
• Zero Current Shutdown Mode (5-pin version)
• Offer in TO-263, TO-252, TO-220, SOT-223, &
New Slim LPDD
• Similar to industry Standard LM3940
Applications
• Powering VGA & Sound Card
• LCD Monitor
• Battery Powered Equipments/Laptop & Notebook
• SMPS Post Regulator / DC to DC Modules
• High Efficiency Linear Power Supply
• Adjustable Power Supply
• Bar Code Scanners
Ordering Information
Devices Package Temp.
LM3940T TO-220-3
LM3940S TO-263-3
LM3940D TO-252
LM3940N SOT-223-3
LM3940J LPDD-3
XX=Output Voltage
-40 °C to 125 °C
-40 °C to 125 °C
-40 °C to 125 °C
-40 °C to 125 °C
-40 °C to 125 °C
Bay Linear, Inc
2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
LM3940
ABSOLUTE MAXIMUM RATINGS
Lead Temp. (Soldering, 5 Seconds).................................260°C Input Voltage ........................................................26V
Storage Temperature Range.............................. -65° to +150°C Maximum Output Current....................................3.5A
Operating Junction Temperature Range Input Supply Voltage (Survival).......... -20V to +60V
LM3940 Control Section........................... -45°C +125°C
LM3940 Power Transistor..........................-45°C +150°C
ELECTRICAL CHARACTERISTICS I
PARAMETER CONDITIONS Typ LM3940
Output Voltage
Output Voltage
Line Regulation
Load Regulation
Dropout Voltage
Quiescent Current IO = 5mA, VIN = V
Short Circuit Current
5mA≤IL≤1.25A
5mA≤IL≤1.25A
IO = 5mA, 4.5V≤V
50mA ≤ I
OUT
IN
≤ 1.25 A
IO = 5mA
IO = 1000mA
= 1250mA
I
O
I
= 1000mA, VIN = V
O
= 1.25A
I
O
RL = 0 1.7 1.2
≤5.5V
, +1V
OUT
OUT
OUT
= 5mA, V
, +1V
=V
IN
+ 1V, I l = 1250mA, C L = 10µF. Ta=25°C, unless otherwise specified.
OUT
Units
Min Max
3.3
3.3
5.0
5.0
20
35 50 mV
120 180
400 600
500 800
240
22
35
3.267
3.234
4.95
4.90
350
3.330
3.366
5.05
5.10
40 mV
35
70
V
V
mV
µA
mA
A
Current Limit
Output Noise Voltage
(10Hz to 100kHz)
IL = 100mA
BLOCK DIAGRAM
V
= 0V (Note 4) 1.7 1.5
OUT
CL = 10µF
= 33µF
C
L
400
260
µV
A
RMS
Bay Linear, Inc
2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com
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