Lm317

LM117/LM317A/LM317 3-Terminal Adjustable Regulator

February 25, 2011

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 fixed regulators. 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 even if 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 highripple rejection ratios which are difficult to achieve with standard 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, it makes 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 1.2Vwhere most loads draw little current. For applications requiring greater output current, see LM150 series (3A) and LM138 series (5A) data sheets. For the negative complement, see LM137 series data sheet.

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

Typical Applications
1.2V–25V Adjustable Regulator

LM117/LM317A/LM317 Package Options Part Number LM117, LM317 LM317A, LM317 LM317 LM317A, LM317 LM117, LM317A, LM317 LM117 LM317A, LM317 Suffix K T S EMP H E MDT Package TO-3TO-220 TO-263 SOT-223 TO-39 LCC TO-252 Output Current 1.5A 1.5A 1.5A 1.0A 0.5A 0.5A 0.5A

906301

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 capacitors in the range of 1μF to 1000μF of aluminum or tantalum electrolytic arecommonly used to provide improved output impedance and rejection of transients.

906354

Scale 1:1

© 2011 National Semiconductor Corporation

9063

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LM117/LM317A/LM317

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

906331

CASE IS OUTPUT
906330

CASE IS OUTPUT

Bottom View NS Package Number H03A

Bottom View Steel Package NSPackage 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)

906336

Side View NS Package Number TS3B

906334

Top View NS Package Number E20A

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LM117/LM317A/LM317

4-Lead SOT-223 (EMP)

TO-252...