LM317M

C

ADJ

R

2

Input

Output

Adjust

Vref=1.25V

V

O

D2

1N4002

R

1

240

I

ADJ

C

0.1

I

F

V

I

D1

1N4002

C

1.0 F

I

LM317M

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SLVS297P – APRIL 2000 – REVISED MARCH 2014

8 Applications and Implementation

8.1 Application Information

The LM317M is a linear voltage regulator. The feedback is the output terminal to adjust terminal differential. The

output voltage can be set to any value from 1.25-V to Vout maximum with two resistors.

8.2 Typical Application

8.2.1 Design Requirements

For this design example, use the parameters listed in Table 1.

Table 1. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

Input voltage range

(Output Voltage + 2.5V) to 37V

Output voltage

8.2.2 Detailed Design Procedure

8.2.2.1 Input Capacitor

An input capacitor is not required, but it is recommended, particularly if the regulator is not in close proximity to

the power-supply filter capacitors. A 0.1-µF ceramic or 1-µF tantalum provides sufficient bypassing for most

applications, especially when adjustment and output capacitors are used.

8.2.2.2 Output Capacitor

An output capacitor improves transient response, but it not needed for stability.

8.2.2.3 Feedback Resistors

The feedback resistor set the output voltage using Equation 2.

(2)

8.2.2.4 Adjustment Terminal Capacitor

The optional adjustment terminal capacitor will improve ripple rejection by preventing the amplification of the

ripple. When capacitor is used and VOUT > 6V, a protection diode from adjust to output is recommended.

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