LM317 Datasheet, PDF (1/3 Pages) ON Semiconductor – 1.5 A Adjustable Output, Positive Voltage Regulator

Description
The 3 1 7 are adjustable 3 - terminal positive -voltage regulators capable of supplying 1.5A over a differential voltage range of 3Vto
40V. They are exceptionally easy to use and require only two external resistors to set the output voltage.
Both input and output regulation are better than standard fixed regulators.In addition to higher performance than fixed regulators,
these regulators offer full overload protection available only in integrated circuits. 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 far 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 primary applications of each of these regulators is that of a programmable output regulator, but by
connecting a fixed resistor between adjustment terminal and the output terminal, each device can be used as a
precision current regulator. Even though the regulator is floating and sees only the input-to-output differential voltage,
use of these devices to regulate output voltages that would cause the maximum-rated differential voltage to be exceeded if
the output became shorted to ground is not recommended.
Features
•Output Voltage Range Adjustable from 1.2 V to 37 V
• Output Current Capability of 1.5 A Max
• Input Regulation Typically 0.01 % Per Input - Volt Change
• Output Regulation Typically 0.1 %
• Peak Output Current Constant Over Temperature
Range of Regulator
• Popular 3-Lead TO-220 Package
• Ripple Rejection Typically 80 dB
Typical application data
V
I
3 _IN
317
ADJ
OUT
2
R1
1
240 Ω
V
0
(see Note C)
C1 = 0.1 Fµ
(see Note A)
C2 = 1
(see Note B)
R2
Note A: Use of an input bypass capacitor is recommended if regulator is far from filter capacitors.
Note B: Use of an output capacitor improves transient response but is optional.
Note C: Output voltage is calculated from the equation:

0 ⁼ V_ref ^V _
R
+¹_R1

Vref equals the difference between the output and adjustment terminal
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