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MCU-Slide13

This diagram highlights the power of combining Microchip core independent peripherals with Intelligent Analog peripherals. At the heart of this circuit is a Programmable Switch Mode Controller (PSMC), a 16-bit event driven PWM with a dedicated 64MHz oscillator and up to six steerable outputs. The PSMC enables high speed synchronous switching, for high efficiency DC/DC (buck) conversion while minimizing the size of the external inductors and capacitors. As the PSMC is a core independent peripheral this design will only require a few lines of configuration code, and zero processor overhead. Features of this LED Buck Convertor include an output voltage sense where the output voltage is fed back to the PSMC via a high speed comparator with an over voltage trip point set by the on board fixed voltage reference. Also, since temperature control is critical for all LED based designs it can be monitored using the onboard ADC. Finally, to control the on the fly dimming of the LED the current sense is fed back via an OpAmp to gain up the signal allowing a smaller current sense resistor to be used. The signal is then compared against a selectable DAC trip point.

PTM Published on: 2013-11-29