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greenpowerZONE Products for the week of December 15, 2008
NEC Electronics Says…
8-bit Microcontroller Lineup for Lighting Applications
MCUs Use Inverter Control to Help Save Energy
Following the release of the world’s first microcontroller (MCU) with four-channel constant-current drive for LED lighting systems, NEC Electronics Corporation has begun shipment of 14 new 8-bit All Flash MCUs for energy-efficient lighting applications. Designed specifically for fluorescent and LED lighting devices requiring low cost, high efficiency and intelligent control, NEC Electronics’ extremely low-power-consuming 78K0/Ix2 devices stand apart from the competition by having two unique 16-bit timers with high-speed pulse-width modulation (PWM) output, three channels of internal comparators, a one-channel operational amplifier with programmable gains and an extended operating temperature range of –40 to +105 degrees Celsius. The 14-device lineup includes 78K0/IY2 MCUs in 16-pin packages, 78K0/IA2 MCUs in 20-pin packages and 78K0/IB2 MCUs in 30-pin packages.
As energy costs for lighting equipment rise, and consumers become more eco-conscious about global warming, lighting has become an area of focus for energy conservation. By switching from incandescent to fluorescent bulbs, and by using an MCU rather than a dedicated integrated circuit (IC) to provide inverter control and dimming functions, lighting manufacturers can control illumination at a fine-grained level and provide communication functions that enable illumination and ambient conditions to be adjusted via remote control, delivering further energy savings and added value.
LED-based lighting systems, which consume less power than other lighting systems, are becoming more popular as major advances in brightness levels are made. However, providing high-brightness illumination in LEDs requires functions to control dimming and manage color, thermal conditions and communication, and this need has increased the popularity of MCUs for system control.
NEC Electronics’ 78K0/Ix2 MCUs are well positioned to take on the challenges of controlling fluorescent and LED-based lighting systems by offering outstanding features in a single chip.
- Inverter and LED dimming control function
Two 16-bit PWM timers and a built-in high-speed oscillator that drives the timers at a maximum clock speed of 40 megahertz (MHz) enable fine-grained inverter control. These timers, each capable of two outputs, make it possible for the MCUs to drive four-channel LEDs with precise dimming and color control.
- Instantaneous control of PWM timer output
Built-in comparators with outputs linked to the PWM timer automatically detect abnormal conditions, such as over-current and over-voltage conditions, and immediately shut down PWM output—without CPU intervention—providing much faster protection against damage than an interrupt-based mechanism.
- Internal power factor correction (PFC) control
An external interrupt and built-in comparators linked to the 16-bit timers fulfill hardware requirements for power factor correction (PFC), while NEC Electronics’ high-performance 78K0 core—along with the on-board hardware multiplier—tackle the software computation, eliminating the need for a dedicated PFC control IC and thereby reducing system cost and space.
- Best-in-class low power consumption
With the same low-power technologies used in NEC Electronics’ low-power 16-bit MCUs, the new 8-bit devices consume only 0.3 micro-amps (µA) during standby operation and 260 µA during operation at 1 MHz, which helps reduce system standby power consumption to meet energy efficient regulations.
- Extended operating temperature range
The new devices are qualified for an extended temperature range from –40 to +105oC, exceeding the extreme ambient temperatures demanded by lighting devices.
- Built-in inter-lighting communications peripheral
A dedicated circuit, including a Manchester encoder/decoder in the digital addressable lighting interface (DALI)-compliant UART, enables lighting control for multiple networked lighting devices.
All in all, these new MCUs with dimming functionality are ideal for lighting equipment products, the market for which is growing as a result of increased awareness of the need for energy efficiency.
EN-Genius Says…
NEC’s new family of microcontrollers with dedicated lighting control peripherals is an excellent example of the kinds of products that will help accelerate the maturity of the intelligent lighting market. Their 78K0/I*2 series of Flash-based controllers adds both power factor control and multiple communication interfaces to the usual set of PWM control functions necessary to support a dimmable Fluorescent or HBLED light. This makes it easy and inexpensive to build high-efficiency lighting controllers that can be commanded remotely via either a manual remote control or a wireless or wired network.
 Designers can quickly implement wireless control by attaching a ZigBee transceiver or other low-cost, wireless networking device to the 78K0 3-wire input or communicating via an industry-standard DALI serial interface. NEC was smart to design the controller for both fluorescent and LED applications since it will be 3 - 7 years before solid-state lighting really starts to displace fluorescent technology in mainstream applications. Designing with this controller will allow manufacturers to offer products that enable smart, cost-effective networked fluorescent lighting today that will be interoperable with the LED-based systems that will be produced in the near future.
Although I was not able to get pricing information before this review went to press, I suspect that the high levels of integration it offers will only add 20% - 30% to the cost of a comparable controller without these advanced features – something that will both help NEC enjoy a significant (if temporary) market advantage and that will help smart lighting gain a foothold in cost-conscious mainstream applications.
Using a Flash-based controller for these kinds of applications makes lots of sense in terms of being able to rapidly turn out updates or new features without changing the BOM on your board. It will also make it easy to adjust your board to accommodate newer, more efficient LEDs and power devices as they become available. Based on experience with early Flash applications from a decade or two ago, I do have some small concerns about whether NEC’s Flash memory can reliably retain its programming for the 20+ years that lighting equipment is expected to remain in service. Unfortunately, the same time constraints that did not allow me to get pricing information before this review went to press prevented me from getting a comment from NEC. If I do hear back from NEC I’ll post what I learn here.
NEC’s 78K0/I*2 controller family consists of 14 devices in three groups: the 78K0/IY2 MCUs in 16-pin packages, the 78K0/IA2 MCUs in 20-pin packages and the 78K0/IB2 MCUs in 30-pin packages. Prices for samples of the MCUs will vary depending on memory capacity, package type, and number of pins. Mass production of all 14 devices is expected to begin May 2009.
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