CXLE87132B is a dedicated LED driver chip that integrates a single-line digital interface, a data latch and a multi-channel constant current driver circuit. It supports the input of a set of data including constant current settings and PWM dimming through an external MCU to achieve independent control of the four LED channels. Chip built-in 5V regulator, the peripheral circuit is simple, suitable for 6~24V wide voltage input environment, widely used in all kinds of LED decorative lighting system.
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[ CXLE87132B ]"
In the application scenarios of LED decorative lighting, guardrail tube, point light source, etc., higher requirements are put forward for the flexibility, accuracy and system expansibility of the driver chip.CXLE87132B as a four-channel LED constant current adjustable driver IC, with its unique current grading ability, high integration andStableThe single-line cascade feature has become the first choice for many lighting designers. This article will be from the technical characteristics, working principle to practical application, a comprehensive analysisCXLE87132B, to help engineers efficiently complete the system design.
1. Chip Overview
CXLE87132B is an integrated single-wire digital interface, data latch and multipleConstant current drivededicated circuitLED driver chip. It supports a set of inputs via an external MCU containing constant current settings andPWM Dimmingdata, to achieve independent control of the four LED channels. Chip built-in 5V regulator, the peripheral circuit is simple, suitable for 6~24VWide voltage inputenvironment, widely used in all kinds of LED decorative lighting system.
2. core features
• Four channel independent outputs: Support OUTW, OUTR, OUTG, OUTB four constant current output, each channel can independently set the current and PWM.
• 64 level constant current adjustableThe output current of each channel can be precisely adjusted from 6.5mA to 38mA to meet different brightness and power requirements.
• 256 levelPWM Dimming: Support high-precision brightness control to achieve smooth brightness change effect.
• High precision output: The current error between channels does not exceed 3%, and the error between chips does not exceed 5%, ensuring system consistency.
• Single-wire serial cascade: Support automatic shaping forwarding, signal transmissionStable, the number of cascades is theoretically unlimited.
• Built-in 5V regulatorVDD built-in regulator, simplify the design of peripheral power supply.
• SOP8 package: Small size, suitable for high-density PCB layout.
3. electrical characteristics and operating conditions
CXLE87132B has excellent electrical performance and reliability:
• OUT port withstand voltage up to 32V, adapt to a variety of LED series structure.
• Operating temperature range -40 ℃ to 85 ℃, suitable for outdoor and industrial environments.
• The data transmission rate is up to 800KHz, supporting high refresh rate applications.
• Quiescent current as low as 0.5mA, excellent power consumption control.
4. Communication Protocols and Data Formats
The chip uses a single-line return-to-zero code communication, and each frame of data contains:
• C1/C2 command: Used to set the constant current value of four channels, 6-bit data for each channel, and support 64-level adjustment.
• Dn command: Used to set the PWM duty cycle of each channel, 8-bit data, support 256-level dimming.
• Reset signal: High level valid, used to trigger data to take effect and system reset.
After receiving the 32-bit data, the chip starts to forward the subsequent data, realizing seamless cascade. The controller only needs to send C1/C2 and multiple sets of Dn data once to realize 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 (WRGB) needs to transmit 32-bit PWM data, which takes 40 μs.
• If the system contains 1000 pixels, the single refresh time is 40ms, and the refresh rate is 25Hz, 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 thermal management
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, serious heat, affecting the system life. In the design, voltage regulation can be achieved through series resistance or optimized LED series connection.
5.4. Expanding the flow scheme.
For larger drive currents, four OUT ports can be used in parallel. For each parallel connection, the maximum output current increases by 38mA, and the maximum output current can reach 152mA after four full parallel connections. This method requires software cooperation to set four sets of register values respectively to realize accurate current control and high brightness drive.
CXLE87132B For each OUT port, if the user needs to expand the driving current, the four OUT ports of WRGB can be shorted and used, each shorted
For each OUT port, the maximum constant current value will be increased by 38mA, and the maximum constant current value can reach 152mA after all four OUT ports are shorted. This method requires software
At the same time, with the control, write four sets of register values, can achieve accurate current control and larger drive current.
6. typicalapplication circuit
In order to prevent the signal input and output pins of the chip from being damaged due to the instantaneous high voltage generated by the live plug and pull of the product during the test, the signal input and
The output pin is connected in series with a 100Ω protection resistor. In addition, the 104 decoupling capacitors of each chip in the figure are indispensable, and the VDD and GND traces to the chip are
The feet should be as short as possible to achieve the best decoupling effect,StableThe chip works.
CXLE87132B is suitable for guardrail tube, point light source, LED subtitle screen 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.
CXLE87132B In the case of the same constant current setting, the current difference between channels and chips is extremely small. The constant current curve shows that 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,StableIt is suitable for RGBW lighting systems with strict requirements on color consistency.
8. Package and Pin Function
Nine,Conclusion
CXLE8713With its four-channel independent control, 64-level current adjustable, high-precision output and flexible cascade capability, 2B excels in the field of LED decorative lighting and control. Whether it is complex color changes or large-scale pixel systems, 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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