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

3

IN

317

OUT

2

V

I

0

ADJ

1

R1

240

Ω

(see Note C)

C1 = 0.1

F

µ

C2 = 1

(see Note A)

R2

(see Note B)

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.



R



Note C: Output voltage is calculated from the equation:

=

V

0

V

ref

 +

1



1

BEIJING ESTEK ELECTRONICS CO.,LTD