Experience synchronized lighting effects with ALI782 and STM32F302VC

Light Temp Click is based on the AL1782, a dual-channel PWM dimmable linear LED driver by Diodes Incorporated. It is a constant-current driver, which can sink up to 1500mA combined or up to 750mA per channel. It has two low-side current sinks, which allow LED strips or LED bulbs to be connected in the common-anode topology for increased effectiveness and power optimization. Note that the constant current on this Click board™ is 750mA per channel. The AL1782 IC can be operated with a PWM signal in the frequency range from 1kHz to 40kHz. Applying the PWM signal with a duty cycle of less than 4ms makes it possible to tune the light intensity of the connected LED light element. A LOW pulse width of more than 4ms will set the device into the low-power mode (suspend). The lowest light intensity that can be reached by applying the PWM frequency of 1kHz is 0.1%, while 40kHz allows the lowest brightness level of 4% of the full light intensity. A High PWM frequency allows for less visible flickering but simultaneously limits the lowest light intensity level. PWM1 and PWM2 pins of the AL1782 are routed to the mikroBUS™ PWM and CS pins and are labeled as PW1 and PW2. Adaptive Thermal Management (ATM) scheme is one of the key features of the AL1782. It can be used to optimize the power consumption by

adjusting the voltage of the external power supply unit (PSU): the excessive voltage applied to the connected LED will be dissipated as heat within the AL1782. Therefore, the voltage level of the external PSU should be kept above the forward voltage of the connected LED plus minimum voltage headroom (VF + VLED_REG). The ATM injects current through the LEDPG pin of the AL1782. This current is converted to a voltage level, and it is sampled by the MCP3221, a low-power 12-bit A/D converter with an I2C interface, by Microchip. It has its I2C pins routed to the respective mikroBUS™ I2C pins, allowing the host MCU to read the LEDPG voltage and adjust the PSU voltage. Please note that if an external PSU with no external regulation is used, its voltage should stay within the mentioned range (VF of the connected LED element + VLEDx_REG as per AL1782 datasheet). However, the voltage should always stay below 30V. The AL1782 IC also integrates many protection features for increased reliability: undervoltage, open or short circuit at the output, and thermal protection. If any of these protections become activated, a fault event will be reported on a dedicated pin labeled FAULTB. This pin is routed to the mikroBUS™ INT pin and is asserted to a LOW logic level when a fault event occurs. Deep Dimming Capability helps with

power efficiency. Subjective perception of the light intensity differs from the measured light. For example, the light intensity of 10% (with respect to the applied duty cycle) is perceived as 32% of the full light intensity. Deep Dimming Capability helps with energy saving, providing an optimal light output. Deep Dimming down to 0.1% is possible with the AL1782 IC since it can be operated with a pulse width as low as one µS while still providing good linearity. Light Temp click is designed to use an external PSU and an MCU. The full potential of the Light Temp click is achieved when combined with a dedicated light temperature and color sensing Click board™ such as Spectral click. By receiving information about the ambient light color temperature and white balance from the Spectral click, the MCU can generate a PWM signal concerning the required CCT tuning and send it to the Light Temp click to regulate the ambient lighting color. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Clicker 4 for STM32F3 is a compact development board designed as a complete solution, you can use it to quickly build your own gadgets with unique functionalities. Featuring a STM32F302VCT6, four mikroBUS™ sockets for Click boards™ connectivity, power managment, and more, it represents a perfect solution for the rapid development of many different types of applications. At its core, there is a STM32F302VCT6 MCU, a powerful microcontroller by STMicroelectronics, based on the high-

performance Arm® Cortex®-M4 32-bit processor core operating at up to 168 MHz frequency. It provides sufficient processing power for the most demanding tasks, allowing Clicker 4 to adapt to any specific application requirements. Besides two 1x20 pin headers, four improved mikroBUS™ sockets represent the most distinctive connectivity feature, allowing access to a huge base of Click boards™, growing on a daily basis. Each section of Clicker 4 is clearly marked, offering an intuitive and clean interface. This makes working with the development

board much simpler and thus, faster. The usability of Clicker 4 doesn’t end with its ability to accelerate the prototyping and application development stages: it is designed as a complete solution which can be implemented directly into any project, with no additional hardware modifications required. Four mounting holes [4.2mm/0.165”] at all four corners allow simple installation by using mounting screws. For most applications, a nice stylish casing is all that is needed to turn the Clicker 4 development board into a fully functional, custom design.