LED driver based on MP3302 LED driver IC. Working circuit diagram.Operates from a single Lithium ion battery


Posted on Feb 5, 2014

MP3302 is a boost converter IC specifically designed for LED drive applications. The MP3302 can drive 27 LEDs (9 strings of 3 white LEDs in series) from a Lithium ion battery. The IC has internal power MOSFETs for driving the LEDs and has an efficiency of 88%. Switching frequency is 1. 3MHz and the internal current limit is 1. 33A. Other features of


LED driver based on MP3302 LED driver IC. Working circuit diagram.Operates from a single Lithium ion battery
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the MP3302 are open load shut down, thermal shut down, under voltage lock out etc. Applications of Mp3302 are LED back lights, LED based lighting gadgets etc. Functional block diagram of the MP3302 is shown below (Fig1). The IC uses a constant current, peak current mode step up regulator scheme for regulating the current through the LEDs. At thebeginning of each oscillator cycle, the control circuitry switches the power MOSFET ON. For preventing sub harmonic oscillation, a stabilizing ramp signal is added to the current sense amplifiers output and the resultant signal is given to the non inverting input of the PWM comparator. When this resultant voltageis equal to the voltage at the PWM comparator`s inverting input (output voltage of the error amplifier), the power MOSFET is switched OFF. The error amplifier`s output is the difference between the feedback voltage and the reference voltage. When the output voltage drops, the feedback voltage also drops and this in increases the output of the error amplifier. This in turn increases duty cycle of the power MOSFET drive signal produced by the control circuitry which increase the duty cycle of the power MOSFET, it conducts more current and the output voltage is regulated. Circuit diagram of a 27 LED driver circuit using MP3302 is shown below (Fig 2). C1 is the input bypass capacitor and C2 is the output bypass capacitor. Resistor R1 is the feedback resistor and it controls the...




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