LM317

3-TERMINAL ADJUSTABLE REGULATOR

SLVS044H – SEPTEMBER 1997 – REVISED DECEMBER 2001

4

POST OFFICE BOX 655303

APPLICATION INFORMATION

R1

240

Ω

IAdj

R2

Cin (Note A)

0.1

µF

CO (Note B)

1.0

µF

VI

VO

NOTES: A. Cin is not required if the regulator is close enough to the power-supply filter.

B. CO improves transient response, but is not needed for stability.

Since IAdj is typically 50 µA, it is negligible in most applications.

Vref = 1.25 V

V

R2

R1

) (I

Adj

R2)

Vout is calculated as:

INPUT

OUTPUT

ADJUST

LM317

Figure 1. Adjustable Voltage Regulator

C1

0.1

µF

R1

120

Ω

R2

3 k

Ω

INPUT

OUTPUT

ADJUST

LM317

VO

+35 V

R3

680

Ω

–10 V

Since IAdj is typically 50 µA, it is negligible in most applications.

V

R2

) R3

R1

) I

Vout is calculated as:

Figure 2. 0-V to 30-V Regulator Circuit