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PIC16F1508 DALI Dimmable Fluorescent Ballast (Proof of Concept)

Design Highlights:

Rapid Start Intelligent Fluorescent Ballast
  • Universal input 1st stage peak current mode boost supply
  • Resonant LCC inverter for lamp drive
  • 120 VAC – 240 VAC Input
    • Single hardware platform
    • Firmware based configuration
  • Active Power Factor Correction (PFC)
    • 0.95 or better (0.98 at full load)
  • PIC16F1508 Controlled Topology
    • Core Independent Peripheral Integration
      • 5-bit DAC
      • Configurable Logic Cell (CLC)
      • PWM
      • Numerically Controlled Oscillator (NCO) Comparators

DALI Communications
Smooth digital dimming control via NCO linear frequency control

    • Analog input or serial e.g. DALI communications
MCP1416 FET Driver
PIC16F1508-dali-dimmable-fluorescent-ballast-700x291

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Theory of Operation

This proof of concept design is a rapid start resonant fluorescent power supply with active PFC.

Controller Topology

  • Peak current mode DCM boost converter at 150kHz+ switching frequency
  • Internal 5-bit DAC used for voltage envelope reference
  • High Performance Comparators used for peak current mode limits
  • CLC for overall integration and SR-Latch
  • NCO for accurate resonant frequency generation
PIC16F1508-controller-topology-500x245

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Tabs / Intelligent Lighting & Control
Products
Documents
Software
Development Tools

The software in this section is subject to the U.S. Export Administration Regulations and other U.S. law, and may not be exported or re-exported to certain countries or to persons or entities prohibited from receiving U.S. exports (including Denied Parties, entities on the Bureau of Export Administration Entity List, and Specially Designated Nationals).

Application Notes

Document Number Title
AN1138 A Digital Constant Current Power LED Driver
AN1050 A Technique to Increase the Frequency Resolution of PICmicro MCU PWM Modules
AN239 Bit Banged LIN Slave Node for PIC16 & PIC18
AN874 Buck Configuration High-Power LED Driver
AN1476 Combining the CLC and NCO to Implement a High Resolution PWM
AN1487 DALI Control Gear
AN980 Designing a Boost-Switching Regulator with the MCP1650
AN1035 Designing with HV Microcontrollers
AN1465 Digitally Addressable Lighting Interface (DALI) Communication
TB094 Dimming AC Incandescent Lamps Using A PIC10F200
AN1261 Dimming Power LEDs Using a SEPIC Converter and MCP1631 PIC Attach PWM Controller
AN948 Efficiently Powering Nine White LEDs with the MCP1650
AN1427 High Efficiency Solutions for Portable LED Lighting
AN1211 Maximum Power Solar Converter
AN1271 Offline Power Converter for High-Brightness LEDs Using the PIC16HV785 Microcontroller
AN1074 Software PWM Generation for LED Dimming and RGB Color Applications
AN1074-Setup Software PWM Generation for LED Dimming and RGB Color Applications
AN954 Transformerless Power Supplies: Resistive and Capacitive
AN-H48 HV9910B: Buck-based LED Driver
AN-H50 HV9910B: Constant, Off-time, Buck-based LED Driver
AN-H64 Compatibility and Functional Differences between the HV9961 and HV9910B LED Drivers
DN-H02 Isolated Constant Power Converter Using the HV9922
DN-H03 Alternate Use of the HV9922 as an Off-line, Non-isolated, 50 to 100 mA Auxiliary Power Supply
AN-H51 Designing a Boost-Buck converter with the HV9930
AN-H58 Improving the Efficiency of a HV9930/AT9933 Boost-Buck Converter

The software in this section is subject to the U.S. Export Administration Regulations and other U.S. law, and may not be exported or re-exported to certain countries or to persons or entities prohibited from receiving U.S. exports (including Denied Parties, entities on the Bureau of Export Administration Entity List, and Specially Designated Nationals).

Software

Title Document Type
DALI Code Library and Demonstration Code Software
DMX512A Code Library and Demonstration Code Software
Lighting Communications Development Platform Highlights & Demonstration Overview Collateral
Lighting Communications Development Platform Schematics Software
Lighting Communications Development Platform Users Guide Collateral
MiWi™ Wireless Networking Protocol to WiFi® Gateway DemonstrationKit (DM182018) Software
MiWi™ Wireless Networking Protocol to WiFi® Gateway Lighting Demonstration Code Software
PIC12F752 AC/DC LED Driver Demonstration Code Software
PIC12F752 AC/DC LED Driver Schematics Software
PIC16F1508 DALI Dimmable Fluorescent Ballast Demonstration Code Software
PIC16F1508 DALI Dimmable Fluorescent Ballast Schematics Software
PIC16F1509 Solar Powered LED Security Lamp Demonstration Code Software
PIC16F1509 Solar Powered LED Security Lamp Schematics Software
PIC16F1788 Wireless DC/DC LED Driver Demonstration Code Software
PIC16F1788 Wireless DC/DC LED Driver Schematics Software
PIC16F1947 Lighting Control Console DALI Demonstration Code (coming soon) Software
PIC16F1947 Lighting Control Console DMX512 Demonstration Code Software
PIC16F1947 Lighting Control Console Schematics Software
Stand-Alone RGBW Demonstration Code Software

Select:

  1. A boost-strapping power supply consisting of 2 Zener diodes is used to supply power to the FET driver and the microcontroller at startup.
  2. The onboard DAC is used as a voltage divider from the external rectified AC supply voltage to supply a line voltage envelope reference for the power factor correcting peak current mode boost converter. Since the DAC has a selectable tap point the amplitude of the reference is controllable from software.
PIC16F1508-dali-flourescent-ballast-system-diagram-400x278 (1)

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  1. A small shunt resistor is used to measure the inductor current and the high performance comparator is used to detect when the inductor current reaches the reference current supplied.
  2. The CLC is used as the heart of the controller set up as an SR-Latch. The latch is set by a PWM control signal which turns on the switching FET and starts a near-linear increase in inductor current.
  3. When the inductor current reaches the reference envelope the comparator trips and resets the output SR-Latch in the CLC. The next pulse starts when the PWM starts its next switching cycle.
  4. An ADC is used to roughly regulate the output of this boost converter to above the line voltage (typically 200V or 400V depending on input voltage).
  5. A resonant half-bridge LCC drive circuit is then used to apply this signal to the lamp.
  6. At startup a high frequency signal is generated to heat the lamp filaments.
  7. Once the filaments are on temperature the frequency is quickly reduced to the point where a striking potential is generated by the resonant circuit and the lamp arc is established.
  1. At this point the intensity of the lamp can be controlled by changing the lamp drive frequency. The intensity setpoint can be provided analog via an ADC channel or digitally via the EUSART which can be used to implement lighting protocols such as DALI or DMX for dimming control and switching the lamp on or of.
  2. A second comparator on the device is available to perform output voltage clamping. The signal can be combined into the SR latch as an auto-shutdown by using the CLC.
PIC16F1508 DALI Dimmable Fluorescent lamp Drive Frequency

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Contact your local sales representative to see a working demonstration of the DALI Dimmable Fluorescent Ballast.

For comments or suggestions on Microchip's Lighting Solutions - please email us at lighting@microchip.com