Simple LED Boost Driver Circuit with IC MP3302

Simple LED Boost Driver Circuit with IC MP3302 is a cool boost converter chip designed to power light-LEDs in different projects.

This chip can light up to 27 LEDs arranged in 9 groups with 3 SMD 2835 LEDs in each group all powered by a Lithium-ion battery.

What makes the MP3302 special is its ability to provide a steady current while controlling several LEDs at once.

The IC is optimized for LED driving applications and can handle up to 150mA output current.

It works well with input voltages between 3 volts and 6 volts making it perfect for battery powered gadgets.

This circuit is great for many uses like LED backlighting, display lights and general LED lighting solutions.

Circuit Working:

Parts List:

The MP3302 LED driver circuit works like a boost converter, which means it raises the input voltage to power several LED strings.

Here is how the working of the circuit operates:

This circuit can take an input voltage between 3V and 6V.

To keep everything running smoothly it uses a capacitor called C1 to filter the incoming power.

The inductor L1 is important for storing energy.

When the internal SW pin of the MP3302 is turned on L1 gathers energy.

When the internal switch turns off the energy stored in L1 is released through a Schottky diode D1.

This diode is key because it stops any reverse current from coming back into the circuit.

The circuit keeps the current flowing through the LED strings steady by using a feedback system.

The feedback FB pin checks the voltage across a resistor R1 to make sure the current stays constant.

There is also an Enable EN pin that allows for PWM dimming.

This means you can change the brightness of the LEDs by adjusting the duty cycle of an external control signal.

Formulas with Calculations:

The formulas with calculations for Simple LED Boost Driver Circuit with IC MP3302 is mentioned below:

Inductor Selection:

The inductance value can be calculated using the formula:

L = (V_IN × (V_OUT – V_IN)) / (I_LED × f_SW × V_OUT)

where,

• V_IN is the input voltage
• V_OUT is the output voltage (depends on LED forward voltage)
• I_LED is the LED current
• f_SW is the switching frequency

LED Current Calculation:

To calculate the R1 resistor value for an LED current of 150mA we use the given formula:

I_LED = 0.2V / R1

where,

• LED Current (ILED​) is 150mA
• Feedback Reference Voltage is 0.2V from MP3302 datasheet

ILED​ = 150mA = 0.150

AFeedback Reference Voltage = 0.2V

Calculating R1,

R1 = 0.2V / 1.50A = 1.33Ω

Output Voltage Calculation:

The output voltage for the LED strings is given by:

V_OUT = N × V_LED

where:

• N is the number of LEDs in series
• V_LED is the forward voltage of each LED

Resistors Selections for R2 and R3:

To calculate the current-limiting resistor for an SMD 2835 LED operating at 150mA, we use ohms Law:

R = Vsupply​−Vf​​ / ILED​

where,

• Supply Voltage (Vsupply​) = 12V (Assuming common LED driver voltage)
• Forward Voltage of LED (Vf) = 3V
• LED Current (ILED​) = 150mA = 0.150A

Calculating Resistor Value for R2 and R3:

R = 12V − 3V​ / 0.150A

R = 9V​ / 0.150A

R = 60Ω

Power Dissipation in Resistor:

P = I² × R

P = (0.150A)2 × 60Ω

P = 0.0225 × 60

= 1.35W

How to Build:

To build a Simple LED Boost Driver Circuit with IC MP3302 follow the below mentioned steps for connections and assembling:

• Gather all the components mentioned in the above circuit diagram
• Connect L1 inductor between pin SW and IN pi of IC1 MP3302
• Connect capacitor C1 from positive supply of 3V to 6V and GND.
• Connect GND pin of IC1 to GND of the circuit.
• Connect the FB pin with the junction of R1 and the LED current limiting resistors.
• Connect anode of the diode the the junctions of the inductor L1 and the SW pin of IC1 and connect the cathode of the diode to the anodes of the LEDs
• Connect the capacitor C2 across the anode of the LEDs and the GND line of the circuit
• The EN pin of the IC is used to turn the circuit ON or OFF and to provide dimming control.

Conclusion:

The Simple LED Boost Driver Circuit with IC MP3302 is a great solution for powering several LED strings with a steady current.

It has a easy design, which allows you to change the brightness using PWM and is very efficient because of its boost converter setup.

This makes it perfect for lighting systems that run on batteries and other LED related uses.

References:

Simple open-circuit protection for boost converters in LED driver applications

Monolithic Power Systems (MPS) MP3302DJ-LF-Z