Adding Intelligence to Lighting Applications

Driving LEDs with a Boost Regulator

A boost regulator topology is used when the output voltage of the converter must be equal to or greater than the input voltage. A boost regulator is useful for driving a chain of LEDs connected in series. It is beneficial to drive multiple LEDs in series. This ensures that all LEDs receive the same amount of current and will have the same brightness level. Using a coupled inductor in the boost circuit reducing the switching voltage requirements of the MOSFET switch. An additional advantage of the MCP1650 in battery applications is the Gated Oscillator Architecture which provides 2 duty cycles reducing high-peak inductor current and output ripple voltages. Input voltages above 3.8V engage a 56% duty cycle and an 80% duty cycle when the input voltage drops below 3.8V, extending battery life in these applications.

MCP1650 Multiple White LED Demonstration Board

The MCP1650 Multiple White LED Demo Board uses the MCP1650 IC to power the nine white LEDs which are connected in series. A PIC10F202 microcontroller in a SOT-23 6-pin package is used to provide the PWM signal to the MCP1650. It also accepts a push button input that allows the user to adjust the white LEDs to three different intensities of 100%, 50% and 25%.

Battery Operated Boost LED Driver Example Using the MCP1650