LM317AEMP/NOPB ACTIVE

Features for the LM317A

• For a newer drop-in alternative, see the LM317
• Typical 0.005%/V line regulation
• 1% output voltage tolerance
• 1.5-A output current
• Adjustable output down to 1.25 V
• Input-output differential up to 40 V
• Current limit constant with temperature
• No output capacitor required
• Short-circuit protected output
• −40°C to 125°C operating temperature range

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Description for the LM317A

The LM317A adjustable 3-terminal, positive-voltage regulators are capable of supplyingcurrent in excess of 1.5 A over a 1.25-V to 37-V output range and provide 1% output-voltageaccuracy. Both line regulation and load regulation are better achieved with the LM317A device thanwith standard fixed regulators.

The LM317A offers full overload protection such as over current, thermal-overloadprotection, and safe-area protection. All overload protection circuitry remains fully functionaleven if the adjustment terminal is disconnected.

Typically, no capacitors are needed unless the device is situated more than 6 inches fromthe input filter capacitors, in which case an input bypass is needed. An optional output capacitorcan be added to improve transient response and can be replaced with a ceramic and appropriate ESR.The adjustment terminal can be bypassed to achieve very high ripple-rejection ratios that aredifficult to achieve with standard 3-terminal regulators.

Because the LM317A regulator is floating and detectsonly the input-to-output differential voltage, supplies of several hundred volts can be regulatedas long as the maximum input-to-output differential is not exceeded. Exceeding the maximuminput-to-output deferential will result in short-circuiting the output. By connecting a fixedresistor between the adjustment pin and output, the LM317A can be also used as a precision currentregulator.

For applications requiring greater output current, see theLM150 series (3A) andLM138 series (5A) data sheets. For thenegative complement, see the LM137 series datasheet.