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Digitally Controlled Adjustable Voltage Regulator Circuit

A Digitally Controlled Adjustable Voltage Regulator Circuit is made to provide a changeable output voltage that can be customized for different circuit needs.

One popular choice is the IC LM317 which is a common voltage regulator that can give an adjustable output from 1.25V to 37V.

In this circuit the IC LM317 works together with digitally controlled transistors allowing users to pick different output voltages.

This is super helpful when you need different voltage levels, like in systems that use microcontrollers, power supplies and testing equipment.

Circuit Working:

Parts List:

Component TypeValue/Part NumberQuantity
Resistor240Ω 1/4 watt1
CapacitorsCeramic 0.1µF1
Electrolytic 10µF1
SemiconductorsIC LM3171
Transistor BC5474

The IC LM317 is a special gadget that helps control voltage and has three important parts.

It works by keeping a steady reference voltage of 1.25V between its output and adjustment parts.

To get the voltage we want we use a group of resistors connected together with the output the adjustment pin and the ground.

In this design we have several resistors named R2, R3, R4, R5 and R6 that help create different voltage levels.

The transistors Q1, Q2, Q3 and Q4 act like little switches.

They help us choose which resistor to use in the voltage setup.

When we turn on a transistor it connects its resistor to the circuit changing the output voltage based on which resistor we picked.

You can figure out the output voltage using this formula for resistors R2 to R6:

V_out = 1.25V × (1 + (R_set / R3)) + I_adj × R_set

Formulas with Calculations:

Below mentioned are the formulas with calculations for Digitally Controlled Adjustable Voltage Regulator Circuit:

V_out = 1.25V × (1 + (R_set / R3)) + I_adj × R_set

In this formula:

Using the above formula:

V_out = 1.25V × (1 + (R_set / 240Ω))

For example, if R_set is 1kΩ than,

V_out = 1.25V × (1 + (1000Ω / 240Ω))

V_out = 6.46V

Similarly, different resistances will provide different output voltages depending on the selection.

How to Build:

To build a Digitally Controlled Adjustable Voltage Regulator Circuit follow the below mentioned steps:

Conclusion:

This Digitally Controlled Adjustable Voltage Regulator Circuit features a voltage regulator that can be adjusted digitally with the help of an LM317.

Users can choose various output voltages by turning on different transistors, which makes it great for projects needing different voltage levels.

This method makes it easier to select voltages in embedded systems, testing tools and DIY power supply projects.

References:

Adjustable/Programmable Voltage Regulators – Linear, Low Drop Out (LDO) Regulators

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