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 termi-nal

is disconnected.

Normally, no capacitors are needed unless the device is situ-ated

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 with stan-dard

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 volt-

age, supplies of several hundred volts can be regulated as

long as the maximum input to output differential is not ex-ceeded,

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. Sup-plies

with electronic shutdown can be achieved by clamping

the adjustment terminal to ground which programs the out-put

to 1.2V where 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.

K TO-3 1.5A

T TO-220 1.5A