A Boost Converter LED Torch Circuit is a simple but really important tool for portable lighting.
This project shows you how to build a super efficient LED torch using the MAX660 chip which acts like a voltage booster.
The IC MAX660 can increase the voltage from a 3V battery making it possible to power several LEDs.
This is especially useful for battery powered devices that need to raise low voltage without using inductors.
Plus, the way this circuit is designed helps the battery last a long time.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Electrolytic Capacitor | 100µF 10V | 1 |
| Electrolytic Capacitor | 22µF 10V | 1 |
| Push to On Switch | – | 1 |
| IC | MAX660 | 1 |
| Diode | 1N4148 | 3 |
| LED | white 5mm 20mA | 3 |
| Battery | 3V | 1 |
The IC MAX660 is a special chip that works as a charge pump voltage converter.
It can either increase or flip electrical voltages.
In this post, it is cleverly designed to act as a voltage doubler changing the input from a 3V battery to about 5V.
This higher voltage is perfect for powering many LEDs very efficiently.
The circuit runs on a 3V battery which is essential for it to work.
The MAX660 uses two capacitors called C1 and C2 to help boost the voltage.
Because of this the chip can provide around 5V making several LEDs shine brightly.
These LEDs are connected in parallel which helps them all light up evenly.
Also, there is a switch S1 that lets users turn the circuit on or off easily making it simple to use the torch whenever needed.
Formulas with Calculations:
To build a Simple Boost Converter LED Torch Circuit using IC MAX660 use the below mentioned formulas with calculations:
Output Voltage Calculation:
The MAX660 operates as a charge pump voltage doubler.
The output voltage is given by:
V_out = 2 × V_in – V_loss
where,
- V_in is 3V Battery input
- V_loss is internal voltage drop around 0.3V to 0.6V due to efficiency losses in the charge pump.
Thus, the expected output voltage is:
V_out = (2 × 3V) – 0.6V V_out = 6V – 0.6V V_out = 5.4V
LED Current Calculation:
The current through each LED is calculated using ohms law:
I_led = (V_out – V_f) / R
where,
- V_f is forward voltage drop of the LED around 3.2V for white LEDs
- R is the series resistor which is not used in this circuit.
Since the LEDs are directly powered, the total current draw is approximately:
I_total = Number of leds × I_led
For 3 LEDs (assuming 20mA per LED):
I_total= 3 × 20mA = 60mA
Capacitor Selection:
The ripple voltage (ΔV) can be approximated using:
ΔV = I / (f × C)
where,
- I is the load current 60mA
- f is the switching frequency of MAX660 around 10kHz
- C is the capacitance 22µF for output capacitor
ΔV = 60mA / (10kHz × 22µF) ΔV = 60mA / 220mF ΔV = 0.27V
Thus, the output ripple voltage is approximately 0.27V which is acceptable for LED operation.
How to Build:
To build a Simple Boost Converter LED Torch Circuit using IC MAX660 follow the below mentioned steps for connections:
- Gather all the components as mentioned in the above circuit diagram
- Connect pin 2 of IC1 MAX660 to positive end of capacitor C1 and negative of capacitor C1 connect to pin 4 of IC1.
- Connect pin 3 of IC1 to GND.
- Connect pin 5 of IC1 to negative of capacitor C2 and positive of capacitor C2 connect to pin 6 of IC1.
- Connect pin 6 of IC1 to positive of capacitor C2 and GND.
- Connect anode of diode D1 to D3 from pin 8 of IC1 and cathode of diodes connect to anode of LED1 to LD3 in parallel and cathode of LEDs connect to pin 5 of IC1
- Connect one end of S1 switch from pin 8 of IC1 and other end of switch connect to positive of 3V battery.
- Connect the negative of battery 3V to GND.
Conclusion:
This Simple Boost Converter LED Torch Circuit using IC MAX660 is a smart and easy way to create battery powered lights.
By using a charge pump method it gets rid of the big inductors which makes the circuit smaller and simpler to put together.
It is perfect for things like emergency lights, portable flashlights and low energy lighting needs.