The LM317M is an adjustable 3-terminal positive voltage regulator capable of supplying
more than 500-mA over an output-voltage range of 1.25-V to
37-V. The LM317M is exceptionally easy to use and requires only two external resistors to set
the output. Furthermore, both line and load regulation are better than standard fixed regulators.
In addition to having higher performance than fixed regulators, the LM317M includes
on-chip current limiting, thermal-overload protection, and safe- operating-area protection. All
overload protection remains fully functional if the ADJUST terminal is disconnected.
The LM317 is a floating regulator meaning there is no device ground terminal. Quiescent
current flows to the load instead of being wasted flowing to ground. Regulated output voltage of
hundreds of volts is possible if the maximum input to output differential does not exceed 40-V at
any time. Device can be used as a floating current source controlled by a single resistor.
Normally, no capacitors are needed unless the device is more than six inches from the
input filter capacitors, in which case an input bypass capacitor of any type is needed. An optional
electrolytic or tantalum output capacitor can be added to improve transient response. Ceramic
output capacitors can be used but output ringing may be present on transients. The ADJUST terminal
can be bypassed with any type of capacitor to achieve high ripple-rejection ratios, which are
difficult to achieve with standard three-terminal regulators.
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