Manuals / Freescale Semiconductor / Computer Equipment / Computer Hardware

Freescale Semiconductor S08 manual LED Driver Design Procedures, RGB LED Chip

Models: S08

1 46

Download 46 pages 43.71 Kb

Page 19

Figure 2-3. DC-to-DC Boost Converter and Linear LED Driver

LED Driver Design Procedures

Vin = 12V

DC-to-DC

Boost

Converter

(MC34063)

Vout = 30V

8 LEDs

8 LEDs

8 LEDs

VLED x 8

R-Channel

PWM

Driver R

G-Channel

PWM

Driver G

Driver B

VREF

B-Channel

ILED = 50mA

VDROP

PWM

Rs

VRS

Figure 2-3. DC-to-DC Boost Converter and Linear LED Driver

Eight pieces of 3-in-1 RGB LED chips connected in series are used to form the multi-color light source. The LED chips are arranged in 2 x 4 format and each RGB LED string is driven by a separated constant current source. The average current through each RGB LED is controlled by an individual PWM signal generated from MCU. The final output color is determined by the mix of light emitted by RGB LEDs that are almost in linear relationship with PWM pulse width. An optical diffuser film should be placed on top of the display window for color mixing and brightness uniformity enhancement.

2.11 LED Driver Design Procedures

This section presents guidelines for selecting external components for DC-to-DC boost converter and linear drivers.

2.11.1 RGB LED Chip

The system is designed to drive eight pieces of RGB LED chips connected in a series. Assume the LED current for each color is 50mA and forward voltage is 2.3V for red LED and 3.3V for green and blue LEDs.

LED Lighting Control using the MC9S08AW60, Rev. 1

Freescale Semiconductor

19

Image 19

Freescale Semiconductor S08 LED Driver Design Procedures, RGB LED Chip, 3. DC-to-DC Boost Converter and Linear LED Driver

Contents

freescale.com LED Lighting Control Using the MC9S08AW60Designer Reference Manual S08 MicrocontrollersPage Revision History LED Lighting Control using the MC9S08AW60Designer Reference Manual Freescale Semiconductor Revision History LED Lighting Control using the MC9S08AW60, RevIntroduction Table of ContentsDemo Setup ChapterAppendix A Schematics Appendix B Bill of Materials Chapter Introduction 1.2 Features1.1 Introduction Table 1-1. Devices in the MC9S08AW60/48/32/16 Series 1.3 System Overview1.4 MC9S08AW60 Figure 1-1 . System Block DiagramMC9S08AW60 FeatureLED Lighting Control using the MC9S08AW60, Rev Table 1-2. Peripherals Available per Package TypeFreescale Semiconductor Introduction LED Lighting Control using the MC9S08AW60, RevFigure 2-1. Light-Box Demo Chapter Hardware Description2.1 Introduction AW60 Control Board2.3 DEMO9S08AW60LED Layout 2.2 DEMO9S08AW60LED FeaturesFigure 2-2. DEMO9S08AW60LED Top Side 2.7 Clock Source 2.5 Power2.6 Reset Switch 2.4 Development Support2.9.3 ADC Interface 2.9.1 Pushbutton Switches2.9.2 LED Indicators 2.9 User OptionsTable 2-7. SPI Port 2.9.4 Other I/O ConnectorsTable 2-5. IIC Port Table 2-6. SCI PortTable 2-9. LED Light Box Interface Table 2-8. PWM PortTable 2-10. Sensor Interface Type A Table 2-12. Temperature Sensor Input Table 2-11. Sensor Interface Type HTable 2-13. User Assignable Input Table 2-13. User Assignable Input Continued 2.10 LED Driving Board2.11.1 RGB LED Chip 2.11 LED Driver Design ProceduresFigure 2-3. DC-to-DC Boost Converter and Linear LED Driver 2.11.3 Boost Converter 2.11.2 Current Sense ResistorFigure 2-4. Equations for Boost Converter Freescale Semiconductor Hardware Description LED Lighting Control using the MC9S08AW60, Rev3.1 Introduction Chapter Firmware DescriptionFigure 3-1. Firmware Flow Main Program Figure 3-2. Firmware Flow PWM Adjustment 3.2 PC Control ModeFigure 3-3. User Interface Menu 3.3 Standalone Mode SCI.c 3.4 Firmware FilesMain.c Menu.cFreescale Semiconductor Firmware Description LED Lighting Control using the MC9S08AW60, Rev4.2.2 PC Software Setup Chapter Demo Setup4.2 Hardware and Software Setup 4.2.1 Hardware SetupDemo Setup Figure 4-1. Echo Typed Characters SettingLED Lighting Control using the MC9S08AW60, Rev 4.3.1 Demo 1 - Demonstration Display 4.3 Demo ExamplesFigure 4-2. LED Control Menu 4.3.5 Demo 5 - Full Manual Control 4.3.2 Demo 2 - Preset Colors Display4.3.3 Demo 3 - Auto White Balance Control 4.3.4 Demo 4 - PWM Output Frequency Control4.4 Program the MCU Flash 4.5 TroubleshootingRepeat the PC software setup procedures again LED Lighting Control using the MC9S08AW60, Rev Appendix A SchematicsFreescale Semiconductor LED Lighting Control using the MC9S08AW60, RevFreescale Semiconductor LED Lighting Control using the MC9S08AW60, RevFreescale Semiconductor LED Lighting Control using the MC9S08AW60, RevFreescale Semiconductor LED Lighting Control using the MC9S08AW60, RevFreescale Semiconductor LED Lighting Control using the MC9S08AW60, RevLED Lighting Control using the MC9S08AW60, Rev Appendix B Bill of MaterialsQuantity LED Lighting Control using the MC9S08AW60, RevTable 4-1 BOM for AW60 Control Board Part DescriptionDesignators Table 4-2 BOM for LED Driving BoardPart Description ValueFreescale Semiconductor LED Lighting Control using the MC9S08AW60, RevPage USA/Europe or Locations Not Listed How to Reach UsHome Page E-mail