Simple High Current Voltage Regulator Circuit using LM317 and LM195

Simple High Current Voltage Regulator Circuit using LM317 and LM195 give steady voltage with big current.

Here IC LM317 regulator work with IC LM195 power transistor.

Together they give steady output with more current than LM317 alone.

IC LM195 is a special transistor with safety protect from overload.

This circuit can handle output current up to 600mA.

It is good for need low dropout and high current voltage control.

Circuit Working:

Parts List:

This article talk about circuit with two parts:

First part LM317 IC1 that control output voltage.

Second part LM195 Q1 power transistor that help handle more current.

Input voltage Vs from 10V to 40V power whole circuit.

LM317 keep voltage steady by change output at adjust pin 1.

LM195 work like current booster.

LM195 get signal from LM317 and send final regulated voltage.

Resistor R1 keep current steady.

Resistor R2 control current to base of LM195 and keep safe.

Capacitor C1 clean noise in power supply.

Circuit give output current up to 600mA.

Formulas with Calculations:

Output voltage formula:

Because LM195 transistor work like emitter follower then output voltage is:

Vout = LM317 output voltage − VBE

VBE is base-emitter voltage drop of LM195 to about 0.7V to 1V which depend on load.

Example LM317 set 5V:

Vout = 5V − 0.7V = 4.3V

For higher output set LM317 to (Vout + 0.7V).

Output current formula:

Max current depend on LM317 current and LM195 gain.

Current through R1 help stabilize.

LM195 gain is high so:

Iout = 1.25V / R1

With R1 = 2.4Ω:

Iout = 1.25V / 2.4Ω = 0.52A (520mA)

Circuit give about 520mA output current.

To get more current reduce R1.

Power dissipation formula:

LM195 get heat from power difference.

Power dissipated by LM195 is:

PLM195 = (Vin − Vout) × Iout

Example Vin=12V, Vout=5V, Iout=0.52A:

PLM195 = (12 − 5) × 0.52 = 3.64W

IC LM195 need good heat sink to avoid damage.

How to Build:

To build a Simple High Current Voltage Regulator Circuit using LM317 and LM195 follow the below mentioned steps for connections:

• Assemble parts like circuit diagram
• Connect ADJUST pin 1 of IC1 to GND
• Connect OUTPUT pin 2 of IC1 to one side of resistor R1 and other side of R1 to GND
• Connect INPUT pin 3 of IC1 to junction of emitter of power transistor Q1 and output 600mA supply
• Connect base of Q1 to input supply through resistor R2
• Connect collector of Q1 to Vs power supply 10V to 40V
• Connect capacitor C1 positive to Vs 10V to 40V and negative connect to GND

Conclusion:

This Simple High Current Voltage Regulator Circuit using LM317 and LM195 is easy way to get more current and steady voltage.

It is good, strong and reliable power supply.

Check if heat dissipation is managed well to work safe.

References:

High current voltage regulator

LM195/LM395 Ultra Reliable Power Transistors