The LM317L-N is an adjustable 3-terminal positive voltage regulator capable of supplying
100 mA over a 1.2-V to 37-V output range. The LM317L-N is easy to use and requires only two
external resistors to set the output voltage. Both line and load regulation are better than
standard fixed regulators. The LM317L-N is available packaged in a standard, easy-to-use
TO-92 transistor package.
In addition to higher performance than fixed regulators, the LM317L-N offers full
overload protection. 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 required unless the device is situated more than 6 inches
from the input filter capacitors, in which case an input bypass is required. 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
Besides replacing fixed regulators, the LM317L-N is useful in a wide variety of other
applications. Because the regulator is floating and sees only
the input-to-output differential voltage, supplies of several hundred volts can be regulated,
provided the maximum input-to-output differential is not exceeded.
The LM317L-N makes a simple adjustable switching regulator, a programmable output
regulator, or by connecting a fixed resistor between the adjustment and output, the LM317L-N 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 1.2 V, where most loads
draw little current.
The LM317L-N is available in a standard 3-pin TO-92 transistor package, the 8-pin SOIC
package, and 6-pin DSBGA package. The LM317L-N is rated for operation over a −40°C to 125°C
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