Tecnico

LM117/LM317A/LM317
3-Terminal Adjustable Regulator
General Description
The LM117 series of adjustable 3-terminal positive voltage
regulators is capable of supplying in excess of 1.5A over a
1.2V to 37V output range. They are exceptionally easy to use
and require only two external resistors to set the output voltage. Further, both line and load regulation are better than
standard fixedregulators. Also, the LM117 is packaged in
standard transistor packages which are easily mounted and
handled.
In addition to higher performance than fixed regulators, the
LM117 series offers full overload protection available only in
IC's. Included on the chip are current limit, thermal overload
protection and safe area protection. All overload protection
circuitry remains fully functional evenif the adjustment terminal is disconnected.
Normally, no capacitors are needed unless the device is situated more than 6 inches from the input filter capacitors in
which case an input bypass is needed. An optional output capacitor can be added to improve transient response. The
adjustment terminal can be bypassed to achieve very high
ripple rejection ratios which are difficult to achieve withstandard 3-terminal regulators.
Besides replacing fixed regulators, the LM117 is useful in a
wide variety of other applications. Since the regulator is “floating” and sees only the input-to-output differential voltage,
supplies of several hundred volts can be regulated as long as

the maximum input to output differential is not exceeded, i.e.,
avoid short-circuiting the output.
Also, itmakes an especially simple adjustable switching regulator, a programmable output regulator, or by connecting a
fixed resistor between the adjustment pin and output, the
LM117 can be used as a precision current regulator. Supplies
with electronic shutdown can be achieved by clamping the
adjustment terminal to ground which programs the output to
1.2V where most loads draw little current.
Forapplications requiring greater output current, see LM150
series (3A) and LM138 series (5A) data sheets. For the negative complement, see LM137 series data sheet.

Features
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Guaranteed 1% output voltage tolerance (LM317A)
Guaranteed max. 0.01%/V line regulation (LM317A)
Guaranteed max. 0.3% load regulation (LM117)
Guaranteed 1.5A output current
Adjustable outputdown to 1.2V
Current limit constant with temperature
P+ Product Enhancement tested
80 dB ripple rejection
Output is short-circuit protected

LM117/LM317A/LM317 Package Options

Typical Applications

Part
Number

Package

Output
Current

K

TO-3

1.5A

LM317A, LM317

T

TO-220

1.5A

LM317

S

TO-263

1.5A

LM317A, LM317

EMP

SOT-223

1.0A

LM117,LM317A, LM317

H

TO-39

0.5A

LM117

E

LCC

0.5A

LM317A, LM317

906301

Suffix

LM117, LM317

1.2V–25V Adjustable Regulator

MDT

TO-252

0.5A

SOT-223 vs. TO-252 (D-Pak)
Packages

Full output current not available at high input-output voltages
*Needed if device is more than 6 inches from filter capacitors.
†Optional—improves transient response. Output capacitorsin the range
of 1μF to 1000μF of aluminum or tantalum electrolytic are commonly used
to provide improved output impedance and rejection of transients.

906354

Scale 1:1

© 2010 National Semiconductor Corporation

9063

www.national.com

LM117/LM317A/LM317 3-Terminal Adjustable Regulator

March 1, 2010

LM117/LM317A/LM317

Connection Diagrams
TO-3 (K)
Metal Can PackageTO-39 (H)
Metal Can Package

906331

CASE IS OUTPUT

Bottom View
NS Package Number H03A

906330

CASE IS OUTPUT

Bottom View
Steel Package
NS Package Number K02A or K02C
TO-263 (S)
Surface-Mount Package

TO-220 (T)
Plastic Package

906335

Top View

906332

Front View
NS Package Number T03B
TO-263 (S)
Surface-Mount Package

Ceramic Leadless
Chip Carrier (E)...