HB-LEDs
OSRAM manufacturers the high-brightness 6W Diamond Dragon LEDs and high-efficacy 1W Golden Dragon Plus LEDs. Included on the demo board are 9 Diamond Dragon LEDs in a variety of colors (warm white, white, ultra white, red, amber, yellow, true green blue and deep blue).

LED Driver
Linear Technology has high-efficiency LED drivers to provide the required voltage and current to power high-brightness LEDs. Included on the demo board is the 2A LT3755-1 LED driver with 3000:1 True Color PWM™ Dimming. The LT3755 and LT3755-1 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs. They drive a low side external N-channel power MOSFET from an internal regulated 7V supply. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages. A ground referenced voltage FB pin serves as the input for several LED protection features, and also makes it possible for the converter to operate as a constant-voltage source. A frequency adjust pin allows the user to program the frequency from 100kHz to 1MHz to optimize efficiency, performance or external component size.

The LT3755/LT3755-1 senses output current at the high side of the LED string. High side current sensing is the most flexible scheme for driving LEDs, supporting multiple configurations. The PWM input provides LED dimming ratios of up to 3000:1, and the CTRL input provides additional analog dimming capability. Both parts are available in the 16-lead (3mm × 3mm) QFN package.

Microcontroller
The Renasas R5F21276SDFP, included on the demo board, is a Single Chip 16-Bit CMOS CPU in the 32-pin package. Key features include a voltage monitor, 25 programmable IO ports, internal or external clock generation, interrupts, 5 timers, serial interfaces (2 UARTs, 4-wire, I2C, LIN) and an A/D Converter.

Ambient Light Sensor
The OSRAM Ambient Light Sensor (SFH 5711) detects brightness in the same way as the human eye. Designed for a wide range of applications, it can be used in situations where systems and equipment need to adjust to ambient light conditions as perceived by the human eye. Even small changes in light can be detected accurately. This allows for light adjustment in tiny steps (nearly continuous dimming), so that devices controlled by the SFH 5711 are always visible.

Reflective Sensor
The OSRAM Reflective Sensor (SFH 9201) is used on the board as a proximity sensor as an alternative to a mechanical switch. It detects infra-red light reflected from an object. The optimal operating distance is from 1 mm to 5 mm. The SFH 9201 has a daylight cut-off filter to reduce interference, and a low saturation voltage to improve detection. The emitter and detector are electrically isolated to minimize noise. The SFH 9201 can be used for position reporting, end position switching, motion transmitting and speed monitoring and regulation. Because the SFH 9201 has no moving parts, unlike mechanical switches, it have very high-reliability and is much more resistant to environmental stresses and vibrations.

Demo Board Demonstration Programs
The demo board has four main demo modes. These modes allow the intensity of the HB-LEDs to be adjusted by the user or by environmental conditions- for example ambient lighting level. A short description of each demo mode is given below:

Potentiometer Brightness Control: In this mode the brightness level of the LED string is controlled by a potentiometer setting. This setting adjusts the dimming value of the LED driver and provides a 1000:1 adjustment in the illumination level.

Reflective Sensor Control: In this mode the illumination level of the LED string can be adjusted by touching one of the OSRAM reflectivity sensors. Each touch adjusts the brightness up by 20%. Once the maximum brightness is achieved a touch reduces the brightness by 20% increments.

Light Sensor: In this mode the illumination level is adjusted based on the ambient light level using the OSRAM light sensor. As the ambient light level increases the illumination level of the LED is increased. This provides a relatively constant brightness level with respect to the background illumination level.

Temperature Reading: In this mode the temperature sensor in the MCU is used to determine the temperature of the printed circuit board. The temperature is displayed by blinking the LEDs in a variable pattern (a series of dots and dashes) that encodes the temperature.

Other Possible Demonstrations
The demo board has a significant amount of functionality that can be used in future feature expansions. These include various control interface protocols (like DALI or Nordic SPI RF remote control), user or remote computer control via the RS-232 serial link, use of the Renasas MCU to add more timing and dimming features to more precisely control the illumination level of the LEDs over time, or to react to the ambient light sensor or touch sensors to better illustrate HB-LEDs as part of a more complex user interface or status indicator in consumer electronics, architectural lighting or industrial control.