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PIC controllers boost next-generation digital power

Chandler, Ariz.&#8212Taking digital power supply technology to the next level, Microchip Technology's dsPIC digital signal controller (DSC) family is designed to maintain the generality and flexibility of a DSP solution (versus a dedicated controller) without the accompanying high cost.

“Power-supplies with higher power or complexity are now poised at a price threshold that is amenable to digital control,” said Sumit Mitra, vice president of the Digital Signal Controller Division. “Our dsPIC switchmode power supply families were developed with input from leading power-supply manufacturers to tip the scale in favor of a digital approach. These devices accelerate innovation by giving early adopters newfound flexibility to create new topologies that were formerly impractical for analog approaches. Early adopters expect to achieve superior levels of customization, resulting in power supplies that are more competitive in their markets.”

The company's 16-bit dsPIC30F1010 and dsPIC30F2020/23 modified Harvard RISC devices, which blend the control advantages of a high-performance 16-bit microcontroller and the relatively high computation speed (for this application) of a fully implemented DSP, are suited as complete digital controllers for multi-loop switch-mode supplies, power inverters, and uninterruptible power supplies. These devices feature a high-speed pulse-width-modulator (PWM) with 10-bit A/D converter for low latency and high-resolution control. The chips enable full control of the power-conversion process via software running on the DSC and through its integrated peripherals.

While the digital feedback loop that defines a digital supply provides neither speed nor accuracy advantages over the traditional analog approach, as first touted by digital proponents, the benefits of full digital control are significant, notes Steve Marsh, director of strategic marketing for the Digital Signal Control Division. The advantages include components that no longer need be oversized to account for component variation; eliminating design concerns about component drift and temperature compensation; and doing away with the manual tweaking of components in end-phase fabrication. In the larger picture, software control means fewer product platforms are required to serve a wider range of applications.



As such, Microchip's software-centric “Level 4” (i.e., full digital control) approach is designed to maximize the cost and performance benefits for power applications requiring a fair degree of multitasking: Power supplies with multiple outputs, coordinated load sharing, hot-swap capability, output coordination, integrated power factor correction, and extensive fault-handling capability. The chip's ultrafast PWM and A/D also benefit digital lighting and liquid crystal display (LCD) backlighting applications.

As for specific performance, the PWM on board the dsPIC30F1010 and dsPIC30F202X devices offer 1 ns duty cycle resolution and seven modes of operation, including standard, complementary, push-pull and variable-phase. The 10-bit A/D converter has up to 12 input channels and samples at up to 2 MSPS. Advanced sampling capabilities include individual triggers for each of four sample and holds, and uniquely timed or simultaneous sampling.

The dsPIC30F1010 devices, working from a 3 to 5.5-volt source, have 6 kbytes of flash memory and two PWM generators, and the dsPIC30F202X have 12 kbytes of flash and four PWM generators. The chips feature 30 MIPS performance at 5 volts; fast, deterministic response; optional PWM dither mode to minimize EMI; extended temperature operation (-40 to +125&degC), and small footprint (6-by-6 mm QFN package).

Development support

The dsPIC30F1010 and dsPIC30F202X DSCs are supported by the MPLAB Integrated Development Environment (IDE), MPLAB C30 C Compiler, MPLAB SIM 30 Software Simulator, MPLAB ICD 2 In-Circuit Debugger, and MPLAB Visual Device Initializer.

Additionally, Microchip expects to offer its dsPICDEM SMPS Buck Development Board. The board is now available for early adopter sampling, and the company anticipates receiving orders for it in September. The company has also introduced an on-line Intelligent Power Supplies Design Center (click here).

The dsPIC30F1010 is available in 28-pin SOIC, SPDIP and QFN packages, and the dsPIC30F2020 is in 28-pin SOIC, SPDIP and QFN packages. The dsPIC30F2023 is in 44-pin TQFP and QFN packages. These DSCs are priced starting at $2.99 each in 10k quantities. General sampling is expected in July (click here), and
volume production is expected in August (to order, click here).

Microchip , 1-480-792-7200, www.microchip.com

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