#### Choose Two Resistors and Find the Output Voltage

<> Referring to Application Note 181 and the LM317 Datasheet:- V
_{OUT}may be from 1.2V to 37V at 1.5 A - V
_{REF}is a typical value of around 1.25 V - I
_{ADJ}is a typical value of around 50 µA

V_{OUT}= V_{REF}(1 + R2 / R1) + I_{ADJ}* R2

#### Choose an Output Voltage and R1, and Find R2

<>Similarly, the equation (1) in the LM317 Datasheet can be solved for R2, allowing us to select an output value and a sample R1 and solve for R2. For this, we use a slightly less precise version of the equation, expressing only the radio of R2 to R1 and the Reference Voltage (see: Answers/FAQs).The 50 µA biasing current is small compared to 5 mA and causes only a small error in actual output voltages.V, Or solving for_{OUT}= V_{REF}(1 + R2 / R1)R2 = R1 * (V_{OUT}/ V_{REF}- 1)

#### Heat Dissipation Calculation for LM317

Equation (3) in the LM317 Datasheet can estimate the heat dissipation. I_{L}is the load current. I

_{G}is the current consumed by the LM317, measured at the Adjustment Pin. The datasheet shows 'Adjustment Pin Current' to be a typical value of 50µA.

P_{D}= ((V_{IN}− V_{OUT}) × I_{L}) + (V_{IN}× I_{G})

For more technical data, see: ~~National Semiconductor~~ Texas Instruments, LM317 - 3-Terminal Adjustable Regulator