MICROCONTROLLERS FOR LAMP BALLAST AT90PWM

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MICROCONTROLLERSFOR LAMP BALLAST AT90PWM
AT8xC5114

• Jean Desuché
• November 2006

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Applications
Fluorescent Lamp

• FLuorescent ballasts (Diffused light)
• Office buildings,
• Stores,
• Displays,
• Residential houses

HID

• High Intensity Discharge (HID) ballasts (Focused
  light)
• Street and exhibition lighting,
• Car headlights,
• Video Projection

LED

• Light Emitting Diodes (LED) ballasts
• Signaling
• Automotive,
• Displays.

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AT90PWM 5114 features summary
All AT90PWM have ISP, One pin DebugWire, RC
oscillators, 64 MHz PLL for PSC core (16 MHz),
Vcc2.7-5.5V
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Fluorescent lamp basics

• Filament is heated (starter or magnetic coupling
  by adjusting PWM frequency
• Mercury vaporize
• A high voltage is applied between 2 electrodes
• Current flows in the tube, controlled by the
  ballast
• Exited Hg ions emmit UV light
• Phosphor coating convert UV to visible light

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Fluorescent lamp application diagram
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HID lamp basics

• HID lamps have internal arc tube and an outer
  envelope
• Tube is filled by high pressure gas
• Mercury vapor
• Metal Halide
• Sodium
• Distance between electrodes is some mm
• High voltage required for start-up (2 to 30 kV)
• Current and voltage (100-400V) is controlled by
  the ballast
• Arc between electrodes emmit light
• Most HID lamps require warm-up period for full
  intensity and a cool-down period before re-strike

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HID application diagram
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AT90PWMx Competitive advantages (1)

• All advantages of Mega48/88 plus
• PSC
• Advanced 12 bits, dual channels, PWM generators
• Two control inputs (one digital, one analog
  comparator) for retriggering and overcurrent
  handling
• PLL Clock up to 64 MHz
• Variable frequency and pulse width
• Enhanced resolution mode (16 bits flank
  modulation)
• Input capture register
• Large number of modes for Lighting, Motor
  Control, DC/DC conversion
• Can synchronize the ADC
• DALI (Digitally Adressable Lighting Interface)
  communication
• 16 17 bits frames
• Manchester coding
• Autobaud

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AT90PWMx PSC Module
PSC Block Diagram
PSC 4 ramp mode exemple
digital Sync Input Analog Sync Input
PSC Edge retrigger mode exemple
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AT90PWMx Competitive advantages (2)

• A/D
• 10 bits, 11 channels, speed 8 µs min
• Improved 2.56V Reference voltage
• Amplifier (One or Two) for A/D
• 250 kHz Synchronous BW, switched capacitor
  amplifier,
• Low offset (5mV at the output)
• Programmable gain 5, 10, 20, 40
• D/A
• 10 bits, with output driver (impedance lt 1KOhm)
• Driver speed, 1 µs on 1 nF load
• A/D, Amplifier D/A can be synchronized with
  Timers PSC
• Comparator
• Fast clocked comparator (16 MHz)
• Offset 5 mV (at the input)
• Programmable comparison voltage (4 fixed levels,
  external, D/A)
• Generates interrupt or updates PSC

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PWM2/3B Changes

• Comparator
• Clock frequency can be up to 16 Mhz (8 Mhz at
  3.3V)
• Analog hysteresis added (50 100mV)
• Amplifier new logic for ADC start leading to
  shorter amplified conversion time
• ADC speed sampling and accuracy at 1 Mhz fixed
  (Still degradation at 2Mhz)
• DAC glitches corrected, DAC amplifier linearity
  corrected
• PSC
• All erratas corrected
• Inverted output in centered mode
• Software input capture (write in register trigger
  an input capture)
• Activity output flags added
• Prescaler modified (larger division factor
  possible)
• DALI
• Reception of manufacturer frames (17 bits) with
  stop bit coded on different ways (0, 1, level,
  Manchester)
• Errata corrected
• PLL can also take its source from XTAL oscillator
• NOTICE Changes with ? may not be upward
  compatible (to be checked case by case)

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AT8xEB5114 Advantages

• Optimized for fluorescent tube Ballast
  controller
• Present system
• ASIC one board per tube
• Tube caracteristics adjustment done by passive
  components
• AT8xEB5114 system
• Microcontroller control one board for all tubes
• Tube caracteristics adjustment done by software
• Low power consumption for start up procedure
• Analog
• 10-bit, 6 channels A/D converter
• Amplifier/rectifier
• Two Flexible 16 bits PWM PFC and lamp control
• RC oscillators to control power consumption
  during start up
• Flash and ROM versions
• Stacked EEPROM

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Tools/Support

• STK520 Starter Kit extension
• DebugWire emulator
• STK520
• AT89EB5114 Emulator
• AT90PWM Dimming Fluorescent Ballast Demo Kit
• AT89EB5114 Fluorescent Ballast Demo Kit
• AT90PWM HID LED Ballast Demo Kits in
  development

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STK520 Starter Kit Extension
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ATAVRFBKIT AT90PWM Fluo Demo Kit

• Specifications
• 400 volt DC bus by a power factor correcting
  boost regulator (PFC)
• 100 to 2 dimming.
• Two lamps T8 18W
• 90 to 265 VAC 50 or 60 Hz
• Controls
• DALI power control
• 0-10 volt power control
• One touch Swiss dimming
• Partlist
• Atmel
• AT90PWM2
• IXYS
• IXI858/859 - Driver/Reference/Interface IC
• IXTP3N50P - TO-220, 500V/3A MOSFET
• IXTP02N50D Depletion mode FET for startup
  voltage
• IXH611S1 - 650V/600mA Half-Bridge Gate Driver
• LDA111S - Clare Optocoupler

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ATAVRFBKIT ballast design schematic
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ATAVRFBKIT ballast design