Simple Boost Converter Circuit using IC LM2577

A Boost Converter Circuit which is often called a step up voltage regulator, is a type of electronic circuit that takes a lower input voltage and turns it into a higher output voltage.

This is super helpful in situations where the power source gives out a voltage that is lower than what the device needs.

The LM2577 is a popular integrated circuit IC used for making these step up voltage regulators easier to design.

This article will explain how the IC LM2577 step up voltage regulator circuit works, the basic formulas you need to know, how to build it and wrap up with some final thoughts.

Circuit Working:

Parts List:

The above circuit diagram shows a step up voltage regulator that uses the LM2577 integrated circuit IC.

This circuit takes an input voltage of 5V and increases it to an output voltage of 12V.

The IC LM2577 acts as a switching regulator, which means it boosts the input voltage to a higher level.

When the switch inside the IC is closed, current flows through an inductor L1, which stores energy in its magnetic field.

During this time, the input voltage powers the inductor, while an output capacitor C3 keeps the voltage steady for the load.

When the switch opens, the energy from the inductor is released.

The collapsing magnetic field of the inductor creates a higher voltage that adds to the input voltage.

This combined voltage charges the output capacitor and supplies power to the load through a Schottky diode D1.

The LM2577 switches between these two phases very quickly, usually at a frequency of 52 kHz, which helps maintain a stable output voltage.

Formulas with Calculations:

Below mentioned are the formulas with calculations for Simple Boost Converter Circuit using LM2577:

Output Voltage:

Vout = Vref × (1 + R2 / R3)

where,

• Vref is the reference voltage of the LM2577 1.23V
• R2 and R3 are feedback resistors.

Example Calculation: Vout = 1.23 × (1 + 17.4kΩ / 2kΩ) = 12V

Inductor Selection:

L = (Vin × (Vout – Vin)) / (f × ∆I × Vout)

where,

• Vin is the input voltage.
• Vout is the output voltage.
• f is the switching frequency of the LM2577 around 52kHz
• ∆I is the desired ripple current 20-40% of load current

Capacitor Selection:

C = Iload / (f × ∆Vout)

where,

• Iload is the load current.
• f is the switching frequency.
• ∆Vout is the allowable output voltage ripple.

Diode Current Rating:

Idiode ≥ Iload × (1 + Vout / Vin)

where,

• Idiode​ is the current that the diode must be capable of handling without overheating or failing, this is the diodes maximum current rating.
• Iload​ the current drawn by the load connected to the output of the circuit.
• Vout​ is the output voltage of the circuit.
• Vin​ is the input voltage supplied to the circuit.

How to Build:

To build a Simple Boost Converter Circuit using IC LM2577 follow the below mentioned connections steps:

• Assemble all the components as mentioned in the above circuit diagram:
• Connect the positive input 5V to Pin 5 VIN of the LM2577 IC through capacitor C1 0.1µF for noise filtering.
• Connect the negative input GND to Pin 3 GRND.
• Connect the 100µH inductor L1 between Pin 4 and the junction point where D1 1N5821 anode.
• Connect the cathode of the 1N5821 Schottky diode D1 to the output positive supply of 12V.
• Connect the 680µF electrolytic capacitor C3 between Vout positive and GND negative.
• Connect resistor R2 15k + 2.4k between Vout and Pin 2.
• Connect resistor R3 2k between Pin 2 and GND.
• Connect resistor R1 2.2k and capacitor C2 0.33µF in parallel between Pin 1 and GND.

Conclusion:

The LM2577 boost converter voltage regulator circuit is an easy and effective way to increase lower input voltages to higher ones.

It requires only a few extra parts and works really well, making it great for many different uses.

If you choose the right component values and build it correctly, the LM2577 can deliver dependable and steady performance for all your voltage regulation needs.

References:

LM1577/LM2577 SIMPLE SWITCHER® Step-Up Voltage Regulator