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1amp led driver IC specs

How to Make 1 A Constant Current LED Driver Circuit

Last Updated on May 8, 2019 by Swagatam 16 Comments

In this article I have explained a simple 1 amp constant current LED driver circuit using the IC MBI6651 from MACROBLOCK. The IC has been specifically designed for operating high power LEDs safely by providing a constant current output. The circuit includes very few external components and therefore becomes very easy to assemble at home.

Table of Contents
  • About the IC MBI6651
  • Typical Application Areas of this device are:
  • Setting the output Current
  • Optimizing External Component Selection
  • Selecting the Schottky diode
  • Selecting the capacitor

About the IC MBI6651

The IC MBI6651 is a high efficiency, step down DC to DC converter chip capable of driving high power LEDs at a safe 1 Amp constant current.

The IC requires just four passive external components for making it functional.

The output current of the IC can be externally set by selecting the appropriate resistor value.

The IC also features a PWM controlled dimming control of the connected LEDs.

Some of the other outstanding features of this IC includes UVLO meaning under voltage lockout, over temperature shut down, LED open circuit protection and LED short circuit protection, all these ensure complete safety to the IC from wrongly configured output loads.

Typical Application Areas of this device are:

Automotive decoration and illumination

LED flood lights using high intensity, high power LED.

The IC also can be used as a constant current source in particular circuit applications.

Setting the output Current

The output current of the IC is fixed through an external resistor Rsen. The output current Iout and the adjustment resistor Rsen has the following relation:

Given Vsen=0.1V

Rsen=(Vsen/Iout)=(0.1V/Iout)

Where Rsen is the value of the external resistor. This resistor is connected across the pin outs SEN and Vsen of the IC.

The optimum current with Rsen 0.1 Ohms is 1000 mA or 1 Amp.

Optimizing External Component Selection

Inductor: Two issues specify the inductor type, the switching frequency and the ripple current. The involved calculation can be written as:

L1>{Vin - Vout - Vsen - (Rds(on) * Iout)} * D/fsw * delta.IL

where, Rds(on) is the on-resistance of the IC's internal MOSFET. The value is typically around 0.45 at 12V

D is the duty cycle of the IC, given as D = Vout/Vin

fsw is the switching frequency of the IC

While designing the inductor for the given circuit, along with the inductance the saturation current must also be taken into account,because these are two basic factors which typically affects the overall performance of the circuit.

The rule of thumb, the saturation current of the inductor should be selected 1.5 times greater than the LED current.

Moreover, selecting high values for the inductance provides better line and load regulation.

Selecting the Schottky diode

The diode D1 shown in the circuit diagram basically acts as the flywheel diode for nullifying the inductor back emf during the periods when the LED is switched OFF.

The diode must be selected with the following couple of important characteristics:

It should have a low forward voltage rating and maximum possible reverse voltage tolerance.

Selecting the capacitor

The general rule is always to select a capacitor value with a voltage tolerance 1.5 times higher than the supply voltage.

Preferably, a tantalum capacitor should be selected because these have high capacitance and low ESR characteristics.

The proposed circuit of 1 Amp constant current LED driver circuit is given below:

The basic operating parameters are given below:

Pin Out Specs:

Courtesy: https://www.homemade-circuits.com/wp-content/uploads/2012/04/mbi6651.pdf

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Filed Under: Lamps and Lights Tagged With: Constant, Current, Driver, LED

About Swagatam

I am an electronics engineer and doing practical hands-on work from more than 15 years now. Building real circuits, testing them and also making PCB layouts by myself. I really love doing all these things like inventing something new, designing electronics and also helping other people like hobby guys who want to make their own cool circuits at home.

And that is the main reason why I started this website homemade-circuits.com, to share different types of circuit ideas..

If you are having any kind of doubt or question related to circuits then just write down your question in the comment box below, I am like always checking, so I guarantee I will reply you for sure!

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