LED Controller Family Offers Quick and Easy Color Mixing

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Achieving consistent color performance with LED design requires a complex set of calculations to account for a variety of factors, such as LED bin information and color degradation over temperature. The EZ-Color LED controller family from Cypress Semiconductor, supported by the PSoC Express™ embedded visual design tool, allows engineers to produce a complete design solution simply by inputting the selected LEDs and choosing a desired color.

With PSoC Express, when designers select a color from a gamut presented on-screen, pre-loaded manufacturers’ specifications and temperature feedback algorithms are automatically applied to the selected design, reducing development time. The EZ-Color controller supports up to 16 independent LED channels with up to 32-bits of resolution per channel, enabling lighting designers to select LED array size and color quality.

The controller also offers dynamic color mixing that makes all colors within the system gamut accessible instead of just the pre-set colors. The dynamic color mixing feature also enables the system to utilize feedback loops to maintain the set color output across temperature. Because a HB LED’s dominant wavelength, luminosity and forward voltage are all dependent on junction temperature, HB LED temperature feedback is critical for control. When the HB LED is enabled, the junction temperature increases. As a result, the wavelength increases whilst forward voltage and luminosity decrease. This produces a challenge when trying to maintain a stable color point, since the system will be using outdated HB LED characteristics.

 

 

The simplest method of controlling the effect of temperature on the HB LED system is through a temperature feedback loop. The temperature feedback loop will use an approximation of the HB LED’s junction temperature using the board temperature, the power of the HB LED and the thermal impedance from junction to board (supplied by the HB LED manufacturer). Temperature feedback loops are simple to implement using the EZ-Color solution. EZ-Color devices can control both digital and analog signals enabling quick use of temperature sensors (thermistors), analog to digital converters, amplifiers, etc. PSoC Express provides temperature compensation algorithms enabling the EZ-Color devices to maintain the correct system color output across temperature. These algorithms update the controllers to account for current HB LED characteristics.

Dimming control or current control of the HB LED is another challenge EZ-Color devices address. Possible designs for current control can involve a PWM or expensive external ICs with external resistor control. The PWM method can dynamically change the brightness through its duty cycle for color mixing and tends to be a more efficient solution because of its flexibility. The EZ-Color solution can support up to 16 independently controlled HB LEDs using the PWM method.

Typical difficulties of using a PWM include high EMI and inherent low frequency flicker. Cypress has addressed these issues with PrISM™ (Precise Illumination Signal Modulation) technology, which uses a spread-spectrum dimming waveform with user-defined signal density to deliver consistent color in varied conditions.

The EZ-Color family includes devices that drive up to four (CY8CLED04), eight (CY8CLED08) and 16 (CY8CLED16) LEDs.

 

FEATURES Flexible integration Up to 16 configurable LED channels 8-32 bits of dimmer resolution LED control plus battery charging, motor control and more. Compatible with I2C, SPI, UART, DMX512 and DALI network protocols Precision color control Binning compensation Temperature compensation All-in-one software Breakthrough low frequency and EMI performance PrISM™ technology Easy-to-use tools Drag and drop designs Minimal coding required

APPLICATIONS Architectural and general lighting Entertainment and stage lighting Signage City beautification Intelligent lighting Landscape Backlighting Retail display

 

 

 Featured Products

Part Number		Description	Data Sheet	App. Notes
CY8CLED04-68LFXI		PSoC LED EZ-Color Drives 4 LEDs
CY8CLED08-48LFXI		PSoC LED EZ-Color Drives 8 LEDs
CY8CLED08-48PVXI		PSoC LED EZ-Color Drives 8 LEDs
CY8CLED16-28PVXI		PSoC LED EZ-Color Drives 16 LEDs
CY8CLED16-48LFXI		PSoC LED EZ-Color Drives 16 LEDs
CY8CLED16-48PVXI		PSoC LED EZ-Color Drives 16 LEDs

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