LM117, LM317-N

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SNVS774L – MAY 2004 – REVISED FEBRUARY 2011

Typical Performance Characteristics (continued)

Output Capacitor = 0

μF unless otherwise noted

Line Transient Response

Load Transient Response

Figure 24.

Figure 25.

APPLICATION HINTS

terminal. The reference voltage is impressed across program resistor R1 and, since the voltage is constant, a

(1)

Since the 100

μA current from the adjustment terminal represents an error term, the LM117 was designed to

returned to the output establishing a minimum load current requirement. If there is insufficient load on the output,

the output will rise.

External Capacitors

An input bypass capacitor is recommended. A 0.1

μF disc or 1μF solid tantalum on the input is suitable input

bypassing for almost all applications. The device is more sensitive to the absence of input bypassing when

adjustment or output capacitors are used but the above values will eliminate the possibility of problems.

The adjustment terminal can be bypassed to ground on the LM117 to improve ripple rejection. This bypass

capacitor prevents ripple from being amplified as the output voltage is increased. With a 10

μF bypass capacitor

80dB ripple rejection is obtainable at any output level. Increases over 10

μF do not appreciably improve the

ripple rejection at frequencies above 120Hz. If the bypass capacitor is used, it is sometimes necessary to include

protection diodes to prevent the capacitor from discharging through internal low current paths and damaging the

device.

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