Microchip aims at LED lighting

Microchip has included a new power building block in a microcontroller aimed at LED lighting.

Called the PIC16(L)F1769, the family has the first PICs to offer two independent closed-loop channels.

The firm has steadily been introducing power control peripheral blocks over the last three years – so-called ‘core independent peripherals (CIPs), including for example its ‘complementary waveform generator’ (COG) which produces non-overlapping waveforms to control synchronous power mosfets.

Its aim is to include peripherals which cut processing load in power applications, to allow its 8bit MCUs to compete with fast 32bit MCUs that implement everything in code, particularly for power engineers used to using hardware.

The latest block, bringing the total to nine including the COG, is called the ‘programmable ramp generator’ (PRG) and automates slope and ramp compensation for multiple independent power channels.

“In a boost converter, for example, when duty cycle gets above 60%, the duty cycle can start to oscillate. Slope compensation stabilises this,” Microchip business development manger Lucio Di Jasio told Electronics Weekly at Embedded World.

There are now so many of these peripherals that it is possible to design similar power converters with more than one topology using PIC MCUs.

In F1769, the firm has included: op amps, a 10bit ADC, 5bit DACs, 10bit DACs, 10bit PWMs, 16bit PWMs, high-speed comparators, two 100mA I/O pins, and these CIPs: two COGs, a PRG, a CLC (configurable logic cell), a DSM (data signal modulator) and a ZCD (zero crossing detector).

“There was a lot of input from the automotive lighting team which had a very specific set of requirements,” said Di Jasio.

A unique, claims the firm, hardware-based LED dimming control function can be created by connecting up the DSM, an op amp and the 16bit PWM. (see block diagram) DSM is a simple block that combines a PWM dimming waveform with a fast mosfet gate switching PWM waveform without truncating any gate switching pules.

steve bush

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via Yuichun