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Freescale single-chip solution enables energy-efficient lighting systems
8-bit HC908LB8 microcontroller designed to improve effectiveness and reduce system complexity and cost
Lamp ballast designers can now meet demands for
energy efficiency by using an advanced 8-bit microcontroller from Freescale
Semiconductor . The HC908LB8 helps create more
energy-efficient and cost-effective lamp ballast systems compared to
traditional technologies on the market today.
The high level of
integration on the HC908LB8 helps simplify overall system design. This makes
the device an attractive solution for smart fluorescent lighting, motor
control, high-intensity discharge lighting and applications that require power
factor correction and/or high-resolution pulse width modulation (PWM).
The drive for energy efficiency
Industrialized countries
throughout the world are committing to improve energy efficiency and cut
greenhouse gas emissions over the next decade. In some cases, this commitment
includes legal mandates that the efficiency of traditional systems be improved,
forcing a migration to new, innovative solutions.
One area impacted by the drive for energy efficiency is the lamp ballast market.
“One of the most prevalent
forms of indoor lighting used today is the ubiquitous fluorescent tube,” said
Mike McCourt, vice president and general manager of Freescale's Microcontroller
Division. “The ever-growing international concern about energy efficiency has
prompted new legislation and programs like the Kyoto Protocol and Energy Star®,
which have exerted renewed pressure on ballast designers to improve the
efficiency of their systems.”
Meeting the needs of the lighting market
Power factor correction (PFC), a key requirement in efficient main-powered applications, converts input
current to a sine wave in phase with input voltage. The result is increased
efficiency, lower signal distortion, reduced running costs and lower noise
emissions. The HC908LB8 performs cost-effective PFC, providing an ideal
integrated solution for main-powered applications.
Controlling the brightness of individual tubes has
consistently provided a challenge for designers of fluorescent lighting systems
— the tube is either fully on or off. Freescale helps address this challenge
with a new module — the high-resolution PWM (HRP) — which is integrated on the
HC908LB8 to continuously control the brightness and allow dimming in a fluorescent lighting
system.
The HC908LB8 is also capable of supporting the digitally addressed lighting interface (DALI) protocol to
provide intelligence in large lighting systems. A DALI-based system, for
example, can be programmed to turn off (or dim) lights near windows, where
adequate natural light is available.
In typical lamp ballast applications, the HC908LB8 could help reduce the total number of discreet
digital system parts by up to 50 percent. This helps deliver the additional
benefits of space conservation — reduced board and manufacturing costs and
decreased administration overhead.
HC908LB8 features
The HC908LB8 is based on Freescale's HC08 central processing unit (CPU), with an 8 MHz internal bus
frequency and software within +/- 2% accuracy. Specific features include:
- 8KB flash memory, 128B random access memory (RAM)
- High-resolution PWM (HRP)
- Two PWM outputs with dead-time insertion
- Shutdown input
- Output resolution of 3.9ns using frequency dithering
- Variable frequency and variable duty cycle modes
- Power factor correction
- Two-channel PWM module, featuring fault input detection and shutdown
- Integrated operational amplifier/analog comparator module
- Seven-channel, 8-bit analog-to-digital converter
- 1 x 16-bit timer with interrupt
- Low voltage inhibit and computer operating properly for noise immunity and software safety
- Clock generation module with resistor-capacitor (RC), internal and external crystal options
- Up to 18 input/output (I/O) (multiplexed with peripherals)
- Keyboard interrupts on seven I/O pins
- High current sink/source on I/O. Typical 10mA
The company's Web site address is http://www.freescale.com/.
[Reprinted with kind permission from Motorola]
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