The CXLE87140H integrates MCU single-wire digital interface, data latch, three-way LED constant current drive and PWM brightness control circuit, supports data input through DIN, and realizes multi-chip cascade through DO port. The external controller only needs one signal line to realize the unified control of multiple chips, which greatly simplifies the system wiring. Chip built-in 5V regulator, support 6~24V wide voltage input, suitable for a variety of power environment.
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[ CXLE87140H ]"
In the LED decorative lighting and control system, the simplicity of the driver chip,,StableEase of expansion is particularly important.CXLE87140H as a single line three channel LED fixedConstant current driveSpecial circuit, with its high integration, flexible cascade mode and accurate current output, has become the ideal choice for guardrail tube, point light source, RGB decorative lighting and other applications. This article will be from the chip characteristics, communication protocols to the actual design points, a comprehensive analysis ofCXLE87140H, which helps engineers get started quickly and optimize system performance.
1. Chip Overview
CXLE87140H internal integrated MCU single-wire digital interface, data latch, three-way LEDConstant current driveAnd PWM brightness control circuit, support through the DIN input data, and through the DO port to achieve multi-chip cascade. The external controller only needs one signal line to realize the unified control of multiple chips, which greatly simplifies the system wiring. Chip built-in 5V regulator, support 6~24VWide voltage inputSuitable for a variety of power supply environments.
2. core features
• Three-channel constant current output: OUTR, OUTG, OUTB three fixed output 14mA, high consistency.
• 256 levelPWM Dimming: Support 256 levels per channelbrightness adjustmentto achieve smooth brightness changes.
• Single-wire serial cascade: Support automatic shaping forwarding, signal transmissionStable, the number of cascading is unlimited.
• High level of integration and simplicity of the periphery: VDD built-in 5V regulator, the peripheral circuit is simple.
• Dual package option: Provide SOP8 and SOT23 -400.00g packages to adapt to different installation spaces.
• High communication rateData transfer rate up to 800KHz, support for high refresh rate applications.
3. electrical characteristics and operating conditions
CXLE87140B has excellent electrical performance:
• OUT port withstand voltage 24V, adapt to a variety of LED series structure.
• Operating temperature range -40 ℃ to 85 ℃, suitable for outdoor and industrial environments.
• Typical quiescent current is 1.2mA with low power consumption.
• The output constant current has high accuracy, small difference between channels, and good system consistency.
4. Communication Protocols and Data Formats
The chip uses a single-line return-to-zero code communication, and each frame of data consists of multiple 24-bit data packets and reset signals:
• Dn packet: 24 bits per packet, respectively control the PWM duty cycle of R, G and B channels (8 bits each).
• Reset signal: Low level active, used to trigger data to take effect and system reset.
After receiving the 24-bit data, the chip starts to forward the subsequent data, realizing seamless cascade. The controller only needs to send data packets of each chip in turn, and finally send a reset signal to complete the configuration and refresh of the entire link.
5. Typical Application Design Guide
5.1. Cascade and refresh rate calculations.
The system refresh rate is directly related to the number of pixel dots. 800KHz communication rate as an example:
• Each pixel (RGB) needs to transmit 24 bits of data, which takes 30 μs.
• If the system contains 1000 pixels, the single refresh time is 30ms, and the refresh rate reaches 33Hz, which meets most dynamic display requirements.
5.2. Power Supply Configuration and Resistance Selection
Configure the VDD series resistance based on the supply voltage (DC):
• 6V power supply is recommended to connect 50Ω resistors in series;
• 12V power supply recommended in series 650Ω resistance;
• 24V power supply is recommended to connect 1.8kΩ resistors in series.
5.3. Constant current optimization and voltage control
In order to ensure that the chip works in the best state, the OUT port voltage is recommended to be controlled between 1.2V and 3V. High voltage will lead to increased chip power consumption, heat serious. Design can pass
The series resistance adjusts the voltage, the formula is as follows:
For example, 24V system drives 6 LEDs (each with a voltage drop of 2V). When the constant current is 14mA, the series resistance is about 750 Ω.
5.4. Expanding the flow scheme.
For larger drive currents, three OUT ports can be used in parallel. For each parallel connection, the maximum output current increases by 14mA, and the maximum output current can reach 42mA after all three parallel connections. This method requires software to cooperate and set three sets of register values respectively to realize accurate current control and high brightness drive.
6. typicalapplication circuit
CXLE8714OH is widely used in guardrail tube, point light source, RGB decorative lighting and other scenes. In the design, attention should be paid:
• 100Ω resistor in series with DIN/DO pin to prevent hot plug damage;
• Connect the 104 capacitor between VDD and GND, and try to be close to the chip pin to improve the system.Stableof sex;
• The signal line should be shielded to avoid interference in long-distance transmission.
Constant current performance and curve analysis of 7.
CXLE8714OH is excellent in constant current output. When the OUT port voltage exceeds 0.8V, it enters the constant current region, and the output current basically does not change with the voltage. Its constant current curve shows that the three-channel output has high consistency and is suitable for RGB lighting systems that require strict color consistency.
8. epilogue
CXLE8714OH with its three-channel fixed constant current output, high precisionPWM DimmingFlexible cascading capabilities and simple peripheral design, outstanding performance in the field of LED decorative lighting and control. Whether it is a simple color display or complex dynamic effects, it can provide reliable hardware support. JTMIC (jtm-ic.com) as the official technology partner of the chip, offering fromSample ApplicationOne-stop service from technical guidance to bulk supply.
For detailed data sheets, design tools or sample support, please visit the JTMIC website or contact our technical team.
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