[FAQ] CCS/LP5036: How to master LP50xx device within five minutes? Please provide the quick start guide of LP5009, LP5012, LP5018, LP5024, LP5030, LP5036 device.

Q1: What’s the right direction when USB2ANY module is connected to the LP50xx EVM?

    Fig.1 shows the right direction when the USB2ANY module is connected to the LP50xx EVM. Please pay attention to the part marked in the blue block. For more details concerning hardware setup of LP50xx EVM, please refer to the corresponding user’s guide. I provide a link here to download the user’s guide of LP5024.

Fig.1

Q2: What is the purpose of color mixing? Is it similar with brightness control? Why there is no individual brightness control for each output channel?

    Color-mixing means that different color can be decomposed of different proportions of RGB.  You can configure the proportions of RGB to get desired colors. The proportions of RGB are controlled by configuring the brightness of each R,G and B LEDs.

    The PWM duty ratio control is related to the brightness of each channel. As shown in Fig.2, PWM duty cycle is defined as the product obtained by multiplying the color-mixing register value (Outx_color) by the related intensity-control register value (LEDx_Brightness).

     Actually brightness of each output channel can be controlled by the register OUTx_Color individually. However, the value of OUTx_Color will affect the proportions of RGB. When color is fixed, the independent intensity control (LEDx_Brightness) is used to achieve accurate and flexible dimming control for every RGB LED module. Besides, OUTx_Color register can be used to adjust the brightness independently for single color LEDs.

Fig.2

Q3: How to make a user-defined dynamic lighting pattern with LP50xx device? Can you provide the sample code and Linux driver?

    Actually, you have two choices to achieve user-defined dynamic lighting pattern with LP50xx device.

    Choice A: You can use micro controller, such as MCU or DSP, to control the LP50XX to achieve a user-defined dynamic lighting pattern.  I provide the links here to download the sample code and Linux driver.

    Choice B: You can initialize, set up and play with the LEDs from a C program through USB2ANY SDK. For more details concerning USB2ANY SDK, such as code example, please refer to this thread. 

Q4: How to control the color temperature of RGB- LEDs using LP50xx device?

Fig.3

    Let (x_i, y_i, i=R, G, B) denote the CIE 1931 chromaticity coordinates and (Φ_i, i=R, G, B) denote the luminous flux of the light emitted by the ith LEDs. (x, y) represents the color coordinates of light synthesized by RGB-LEDs. CCT means correlated color temperature. Since variations of the (x_i, y_i, i=R, G, B) are relatively small, the CCT synthesized by RGB-LEDs can be expressed as a function of the flux ratios Φ_i/ Φ_B.

    Hence, you can control the color temperature by adjusting the proportions of RGB by OUTx_color according to the formulas shown in Fig.3.

Q5: How to estimate the junction temperatures of LP50xx device?

    Since there is only a very small percentage of heat energy in a typical plastic package is convected and radiated off the top surface of the package. Hence, if one assumes the entire power is dissipated by the top surface, the junction temperature calculated by R_θJC is higher than reality.

    This limitation of R_θJC is overcome by the new thermal metric, Ψ_JT. Ψ_JT is recommended to estimate the junction temperatures.

    For calculation of Pd (power dissipation), please refer to the training video here.

    For more details about Ψ_JT, You can refer to the application report of "Semiconductor and IC Package Thermal Metrics".