LM317 / LM337 adjustable regulator calculator

LM317 / LM337 Adjustable Regulator Calculator

V_out = V_ref(1 + R2/R1) + I_adj·R2. Solve Vout, R2, R1, or Rs (constant-current mode). Compare ideal vs nearest E-series values. Includes dropout/headroom and power dissipation.

Regulator

What to solve

Reference voltage V_ref

Adjust pin current I_adj (optional)

Target V_out (for R1/R2 solve)

R1 (OUT→ADJ)

R2 (ADJ→GND)

Constant-current set (I)

Load resistor (optional)

Input voltage V_in (optional)

Load current (optional)

Regulator dropout @ load

Extra headroom (ripple/diodes)

Using your values (ideal)

Vout (ideal)

R2 (ideal)

R1 (ideal)

Rs for constant current

Load voltage (at I)

Recommended V_in minimum

Regulator dissipation P_reg

R1 dissipation

R2 dissipation

Rs dissipation

Load resistor dissipation

Using nearest standard

Nearest resistor series

R1 (nearest standard)

R2 (nearest standard)

Vout (rounded)

Error vs target/ideal

Rs (nearest standard)

I (with Rs_std)

Load voltage (with Rs_std)

Rs dissipation (rounded)

Load dissipation (rounded)

LM317 / LM337 adjustable regulator calculator