CXLE87211B is a four channel LED driver chip manufactured using power CMOS technology, integrating MCU digital interface, data latch, and LED constant current driver circuit. Its VDD pin is equipped with a built-in 5V voltage regulator, supporting a wide voltage input range of 6-24V. The peripheral circuit is simple, greatly reducing system design and material costs. This chip is suitable for various LED decorative lighting scenarios, with excellent electrical performance and reliable operational stability.
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[ CXLE87211B ]"
CXLE87211B four channel LEDconstant current driveIC: A high-performance and highly reliable lighting control solution
In modern LED lighting and decoration applications, high efficiencystableThe driver chip is the key to achieving high-quality visual effects.CXLE8721As a four channel LED constant current adjustable driver IC, 1B is widely used in LED decorative products such as guardrail tubes and point light sources due to its excellent performance, flexible dimming control, and high integration. This article will provide an in-depth analysisCXLE8721The functional characteristics, working principles, and application recommendations of 1B help engineers better understand and apply the chip.
1、 Product Overview
CXLE87211B is a four channel device manufactured using power CMOS technologyLED driver chipIntegrated MCU digital interface, data latch, and LEDconstant current driveCircuit. Its VDD pin is equipped with a built-in 5V voltage regulator, supporting 6-24VWide voltage inputThe peripheral circuit is simple, greatly reducing system design and material costs. This chip is suitable for various LED decorative lighting scenarios, with excellent electrical performance and reliable operationstableSex.
2、 Core Features
• High voltage outputThe OUT port has a voltage resistance of 32V and is suitable for various LED load configurations.
• Wide voltage inputVDD has a built-in 5V voltage regulator, which can support 6-24V power input when connected in series with resistors.
• 64 level constant current regulationThe output current of each channel can be precisely adjusted within the range of 6.5mA to 38mA.
• 256 levelsPWM dimmingSupport high-precision brightness control to achieve smooth brightness changes.
• High precision outputChannel error≤± 3%, inter chip error; 5% to ensure color consistency.
• Single line serial cascadeSupports infinite cascading, automatic signal shaping and forwarding, without attenuation or distortion.
• Built in power on resetAfter the system is powered on, it automatically initializes to improve system reliability.
• High transmission rateThe data transmission rate reaches 400KHz and the response is fast.
• Compact packagingAdopting SOP8 encapsulation, suitable for applications with limited space.
3、 Pin function andElectrical parameters
CXLE87211B provides 8 pins, including 4 constant current output terminals (OUTR/OUTG/OUTB/OUTW), data input (DIN), data output (DO), power supply (VDD), and ground (GND). The voltage range of its logic power supply is 4.5V to 6.5V, the maximum voltage of the OUT port is 24V, and the operating temperature range is -40 ℃ to+85 ℃, suitable for harsh environments.
In terms of electrical characteristics, the chip has a static current as low as 0.5mA, an output constant current range of 6.5mA to 38mA, strict control of inter channel and inter chip errors, and a power consumption as low as 250mW, demonstrating excellent energy efficiency performance.
4、 Communication Protocol and Data Format
CXLE87211B adopts single lineserial communicationProtocol, supporting standardized data transmission. A complete data structure includes:
• C1/C2 commandUsed to set constant current values for each channel, with 6 bits per channel and a total of 64 adjustable levels.
• Dn commandUsed to set the PWM duty cycle for each channel, with 8 bits per channel and a total of 256 adjustable levels.
• Reset signalHigh level effective, used to trigger chip update output.
The chip automatically forwards subsequent data after receiving 32-bit data, achieving seamless cascading. When the Reset signal arrives, the chip will update the constant current setting based on the received C1/C2 data and output the corresponding PWM waveform based on the Dn data.
5、 TypicalApplication CircuitDesign Suggestions
5.1. power configuration
CXLE87211B supports 6-24V power input, and a current limiting resistor needs to be connected in series between the power supply and VDD. For example:
• When inputting 6V, it is recommended to connect 50&Omega in series; Resistance;
• It is recommended to connect 650&Omega in series when inputting 12V; Resistance;
• It is recommended to connect 1.8k&Omega in series when inputting 24V; Resistance.
CXLE87211B can be configured for DC6-24V voltage supply, but different power resistors and resistance meters should be configured according to different input voltages
Calculation method: The VDD port current is calculated at 10mA, and the VDD series resistance R=(DC-5.5V)÷ 10mA (DC is the power supply voltage).
The list of typical values for configuring resistors is as follows:
5.2. Signal protection
To prevent chip damage caused by live plugging and unplugging, it is recommended to connect 100Ω in series with DIN and DO pins; Resistors should be connected in parallel with 104 capacitors between VDD and GND, and decoupling capacitors should be placed as close as possible to the chip pins.
5.3. Constant current optimization
To maintain the optimal constant current state, it is recommended to control the OUT port voltage between 1.2V and 3V. Excessive voltage will increase power consumption and heat generation, affecting system reliability.
CXLE87211B is a constant current adjustable drive. According to the constant current curve, when the OUT port voltage reaches 0.8V, it will enter a constant current state. But it's not
The higher the voltage, the better. The higher the voltage, the greater the power consumption of the chip, and the more severe the heating, which reduces the reliability of the entire system. Suggest OUT port
When turned on, a voltage between 1.2 and 3V is more suitable, and the excessive voltage at the OUT port can be reduced by connecting resistors in series.
5.4. Expansion design
If a larger driving current is required, multiple OUT ports can be short circuited for use. For each port short circuited, the maximum output current increases by 38mA, and after three ports are short circuited, the maximum can reach 152mA. The software needs to synchronously configure the corresponding registers to achieve precise control.
6、 Data refresh rate calculation
The system refresh rate is related to the number of cascaded pixels. Taking 400KHz data rate as an example:
• Each pixel has a transmission time of 32 bits× 2.5μs = 80μ s；
• If the system contains 1000 pixels, the total refresh time is 80ms, and the refresh rate is approximately 12.5Hz.
The following table shows the refresh rate reference for different cascading points:
| Pixel count | Refresh time (ms) | Refresh rate (Hz) |
|---|---|---|
| 1~400 | thirty-two | thirty-one point two five |
| 1~800 | sixty-four | fifteen point six three |
| 1~1000 | eighty | twelve point five zero |
7、 Constant current performance and curve analysis
CXLE87211B performs excellently in constant current control, entering a constant current state when the OUT port voltage reaches 0.8V. Its output current remains high when the load voltage changesstableAs shown in the figure:
! [Constant current curve graph]
The blue, yellow, and purple curves in the figure correspond to constant current settings of 38mA, 21mA, and 6mA, respectively, demonstrating the excellent constant current characteristics of the chip at different voltages.
8、 Packaging and mechanical dimensions
CXLE87211B adopts SOP8 packaging, which is compact in size and convenient for PCB layout and soldering. The specific dimensions are as follows:
| parameter | Minimum value (mm) | Maximum value (mm) |
|---|---|---|
| A | one point three five zero | one point seven five zero |
| D | four point seven zero zero | five point one zero zero |
| E | three point eight zero zero | four |
| E1 | five point eight zero zero | six point two zero zero |
9、 Conclusion
CXLE8721As a high-performance and highly integrated four channel LED driver IC, 1B has precise constant current control and flexiblePWM dimmingWith reliable cascading communication capabilities, it is suitable for various LED decoration and lighting systems. Its excellent electrical characteristics and simple peripheral circuit design greatly enhance the competitiveness and reliability of the product.
To learn more aboutCXLE8721Technical documentation for 1BSample RequestFor purchasing information, please visitJTM-IC official websiteWe are committed to providing customers with high-quality integrated circuit solutions andTechnical SupportTo assist in the innovation and upgrading of your products.
