![]() ![]() You can use this Voltage Regulator Calculator to vary the value of the program resistor (R 1) and output set resistor (R 2) and calculate the output voltage for the LM317 / LM338 / LM350 family of three terminal adjustable voltage regulators. LM317 / LM338 / LM350 Voltage Regulator Calculator Photograph 1: LM317 Voltage Regulator (TO-220 Plastic Package) Refer to the adjustable regulator data sheets below for more information about the LM317 / LM338 / LM350 adjustable voltage regulators. The adjustment terminal of the regulator can be bypassed to achieve very high ripple rejection. An optional output capacitor can be added to improve transient response. Normally, no capacitors are needed unless the device is situated more than 150 mm (6 inches) from the input filter capacitors in which case an input bypass capacitor is required. The LM317 / LM338 / LM350 voltage regulators offer full overload protection. You can expect performance of both the line and load regulation using the LM317 / LM338 / LM350 adjustable voltage regulators over that of standard fixed voltage regulator. The LM317 / LM338 / LM350 voltage regulators are exceptionally easy to use, requiring only two external resistors to set the regulated output voltage. Where greater output current is required, the LM350 series regulators are suitable up to 3A and the LM338 series voltage regulators for up to 5A of output. The LM317 voltage regulators can provide up to 1.5 Amperes (A) of output current. A heatsinking is required to keep the regulator cool.The LM317 / LM338 / LM350 family of adjustable 3-terminal positive voltage regulators can take a input of 3 to 40 Volts DC and provide a regulated voltage over a 1.2V to 37V output range. This voltage drop across the regulator is called “dropout”. for example, if we need to 9v at output then the input voltage will need to minimum 12 volts or more if the output voltage is to remain stable under maximum load conditions. The main disadvantage of LM317 is the voltage is that as much as 2.5 volts is dropped or lost as heat across the regulator. Output Safe-Area Compensation Disadvantages of the LM317.Internal Short-Circuit Current Limiting.Output Voltage Range Adjustable From 1.25 V to 37 V.I adj is very small amount and it can be ignored in practical applicationĭetermine the Regulated output voltage of a circuit which haveR1=240 Ω and R2=2.4KΩ Since the LM317 is a floating regulator, it is only the voltage differential across the circuit which is important to performance, and operation at high voltages with respect to ground is possible. If the load current is less than this minimum, the output voltage will rise. (I Adj) represents an error Current from the adjustment terminal, With a Typical LM317 IC value Iadj is to less than 100μ A and keeps it constant. The output voltage desired can be calculated using. This reference voltage is converted to a programming current (IPROG) by R1, and this constant current flows through R2 to the ground. The LM317 develops and maintains a nominal 1.25 V between its output and adjustment terminals called reference voltage (Vref). This device can also be used as a programmable output regulator, or by connecting a fixed resistor between the adjustment and output, the LM317 can be used as a precision current regulator. Overload protection remains functional even if the ADJUST terminal is disconnected. It has current limiting, thermal overload protection, and safe operating area protection. Resistors R1 and R2 set the output to any desired voltage over the adjustment range 1.2v to 37v. To set the output voltage it requires only two external resistors. This regulator IC capable of supplying more than 1.5 A over an output-voltage range of 1.25 V to 37 V. The LM317T is an adjustable three-terminal positive-voltage regulator. 1.5 A Adjustable DC Variable Voltage Regulator Using LM317 ic lm317 voltage regulator working ![]()
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