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 high ripple 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 in
The LM117 series provides adjustable positive voltage regulation with output currents up to 1.5 A and an output range of 1.2 V to 37 V. The devices include internal overload protection, low ripple rejection, and can be used in a variety of applications such as programmable regulators and precision current sources.
The document includes electrical characteristics, package options, ordering information, and application hints for optimal performance, including recommended external capacitors and layout considerations.
| Maximum Output Current | 1.5 A |
|---|---|
| Adjustable Output Voltage Range | 1.2 V – 37 V |
| Ripple Rejection | 80 dB |
| Line Regulation | 0.01 %/V (LM317A) |
| Load Regulation | 0.3 % (LM117) |
The LM117 develops a nominal 1.25 V reference voltage between the output and adjustment terminals.
The TO‑3 (K) package supports up to 1.5 A output current.