LM317
New Product
Vishay
formerly General Semiconductor
3-Terminal Adjustable Output Positive Voltage Regulators
Pin Arrangement
TO-263
(LM317CM)
2
3
3
1
1.
Adjust
2.
V
out
3.
V
in
Heatsink is connected to pin 2
Description
The LM317 is an adjustable 3-terminal positive voltage
regulator capable of supplying in excess of 1.5A over an
output voltage range of 1.2V to 37V. This voltage regulator
is exceptionally easy to use and requires only two external
resistors to set the output voltage. Further, it employs internal
current limiting, thermal shutdown and safe area compen-
sation, making it essentially blow-out proof.
TO-220
(LM317CT)
1
2
Features
• Output current in excess of 1.5 ampere
• Output adjustable between 1.2V and 37V
Standard Application
V
in
V
out
LM317
C
in
0.1µF
I
ADJ
R1
240Ω
Adjust
R2
C
o
1µF
• Internal thermal overload protection
• Internal short-circuit current limiting
constant with temperature
• Output transistor safe-area compensation
• Floating operation for high voltage applications
• Eliminates stocking many fixed voltages
Notes:
Cin is required if regulator is located an appreciable distance from power
supply filter.
Co is not needed for stability, however, it does improve transient response.
V
out
= 1.25V (1 + R
2
/ R
1
) + I
Adj
R2
Since I
Adj
is controlled to less than 100µA, the error associated with this
term is negligible in most applications
Mechanical Data
Case:
TO-220 and TO-263 packages
Weight:
approx. 1.35g
Case outlines are on the back page.
Input
3
Functional Block Diagram
+
--
Voltage
Reference
Protection
Circuitry
Rlimit
Vadj
1
2
Output
Ratings at 25°C ambient temperature unless otherwise specified.
Maximum Ratings
Parameter
Symbol
V
i
-V
o
TO-220
TO-263
R
θJC
P
D
T
J
T
stg
Value
40
3.0
3.0
15
0 to +125
–65 to +150
Unit
Vdc
°C
W
°C
°C
www.vishay.com
1
Input-Output Voltage Differential
Junction-to-Case Thermal Resistance
Power Dissipation, 25°C Case Temperature
Operating Junction Temperature Range
Storage Junction Temperature Range
Document Number 74809
30-Oct-02
VISHAY [ VISHAY TELEFUNKEN ]
