CXLE82135XJ is a highly integrated driver chip designed for non-isolated step-down constant-current LED power supply, supporting 85Vac to 265Vac global universal input voltage. The chip uses inductor current critical continuous mode, integrates 500v high-voltage power switch internally, and uses unique demagnetization detection technology and high-voltage JFETs power supply architecture, without external VCC capacitor and starting resistor, it greatly simplifies the peripheral circuit and reduces the system cost and volume.
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CXLE82135XJ external OVP step-down LED constant current driver chip deep analysis-JTM-IC highly reliable DIP7 packaging solution
In the field of LED lighting drive, high reliability, flexible protection and easy-to-produce packaging form are the key considerations for design and selection. JTM-IC (jtm-ic.com) launched CXLE82135XJ external OVP step-down LED constant current driver chip, with its adjustable open circuit protection, intelligent enable control and classic DIP7 package, it provides stability for medium and high power non-isolated LED lighting, an integrated solution that is flexible and easy to assemble. This article will deeply analyze the technical architecture, design key points and typical applications of the chip to help engineers build high-performance and high-reliability lighting products.
I. ChIP Overview and core positioning
CXLE82135XJ is a highly integrated driver chip designed for non-isolated step-down constant-current LED power supply, supporting 85Vac to 265Vac global universal input voltage. The chip uses inductor current critical continuous mode, integrates 500v high-voltage power switch internally, and uses unique demagnetization detection technology and high-voltage JFETs power supply architecture, without external VCC capacitor and starting resistor, it greatly simplifies the peripheral circuit and reduces the system cost and volume.
Its core highlight isExternal adjustable OVP (overvoltage protection) functionAndIntelligent Enable control, you can flexibly set the open circuit protection voltage through the external resistor of the ROVP pin. At the same time, the pin has both enable and control, which is perfectly adapted to intelligent lighting scenarios such as switch color mixing and human body induction. Chip useDIP7 direct plug package, convenient for manual welding, maintenance and heat dissipation, especially suitable for applications requiring production adaptability.
II. Main features and technical advantages
· Flexible external OVP protection: the ROVP pin resistance can accurately set the open circuit protection point to improve the safety of the system in the abnormal open circuit state.
· Enable control: The ROVP pin supports the enable function. When the voltage is lower than 0.3V, the chip is turned off. It is suitable for intelligent applications such as dimming, color mixing, and induction control.
· High integration and simplified power supply: Built-in high-voltage JFET power supply, no need to assist VCC capacitor and start resistor, and few peripheral devices.
· Wide input voltage range: Compatible with 85Vac ~ 265Vac full range input, suitable for global market.
· High precision stable output current: the output current accuracy is as high as ± 5%, ensuring uniform LED brightness and excellent line voltage and load adjustment rate.
· Comprehensive protection mechanism: Integrated LED short circuit protection, chip power supply undervoltage protection, adjustable OVP and overheating regulation and other multiple protection.
· Classic DIP7 package: direct plug-in package, good heat dissipation performance, easy for manual welding and testing, suitable for a variety of production processes.
III. Detailed explanation of internal structure and working principle
CXLE82135XJ is highly integrated internally, including Vcc power supply module, undervoltage locking, OVP control logic, overheating regulation, constant current control and logic core, leading edge blanking and high precision current detection circuit.
Startup Process: After the system is powered on, the rectified bus voltage supplies power to the internal circuit of the chip through the HV pin. When the internal voltage reaches the start threshold, the control circuit starts to work. When the chip is running normally, its work current is continuously provided by internal high-voltage JFETs without external auxiliary power supply.
Constant current control mechanism: the chip works in the critical conduction mode and achieves constant current by detecting the peak inductor current cycle by cycle. The external current sampling resistor RCS of the CS pin compares the voltage at both ends with the internal reference voltage 373mV. When the CS voltage reaches the threshold, the Power Tube is turned off.
The average LED output current is determined by the following formula:
When designing, you only need to adjust the RCS resistance to accurately set the required output current.
3.2. Internal structure
IV. Design and model selection guide of key peripheral components
4.1. Design of energy storage inductance
Inductance is the key component to ensure that the system works in critical mode. The calculation formula is as follows:
Where IPK = 2×iled, f is the operating frequency of the system.
To ensure constant current accuracy, the Power Tube off-time off off toff must be met:
Beyond this range, the system may enter intermittent or continuous mode, causing the output current to deviate from the design value.
4.2. External OVP resistance setting
The open circuit protection voltage point can be set by the resistor ROVP connected between the ROVP pin and ground. The typical output current of this pin is 30μa.
First, estimate the demagnetization time TOVP based on the target protection voltage VOVP:
Then calculate ROVP:
Note: If the OVP function is not required, the ROVP pin can be suspended. If the Enable function is required, make sure that the ROVP resistance is> 15kΩ.
V. Perfect protection function system
CXLE82135XJ a multi-level security network has been established to ensure the stability and reliability of the system in various abnormal situations:
· LED short circuit protection: when the output is short circuit, the chip automatically enters the low frequency (4kHz) intermittent working mode, with extremely low power consumption to avoid thermal damage.
· Power supply undervoltage protection: monitor the internal power supply voltage in real time to ensure that the chip will not misoperate when the voltage is insufficient.
· Adjustable open circuit protection: set the OVP point through external resistor to effectively prevent the component from being damaged due to excessive output voltage when the LED is open.
· Overheating adjustment: When the chip junction temperature exceeds 140℃, the output current is automatically linearly reduced to realize closed-loop temperature control, keeping the chip temperature within a safe range, greatly improving the long-term reliability of the system.
VI. PCB layout and heat dissipation design suggestions
Good PCB design is crucial to performance, EMI and reliability:
6.1. Current sampling loop (CS & GND): The Power ground wire of the sampling resistor should be as short and thick as possible, and be routed separately to the ground terminal of the input bus capacitor, which is separated from the chip signal to avoid noise interference.
6.2. High voltage pin (HV): keep away from low voltage sensitive pins such as CS when the layout allows.
6.3. Power loop: reduce the primary loop formed by power inductor, power tube inside the chip, input capacitor, and secondary loop area formed by power inductor, flyback diode, and output capacitor as much as possible to reduce electromagnetic radiation (EMI).
6.4. Heat dissipation treatment:
· DRAIN pin: increase the area of its connection copper foil appropriately to help the chip heat dissipation, but pay attention to balance. Excessive copper foil may worsen EMI.
· CS pin: Copper can also be properly supplemented to assist in heat dissipation.
· GND pin: it must be directly connected to the negative terminal of the input bus capacitor, and cannot be connected only to the rectifier Bridge output terminal to ensure a stable reference ground.
7. Typical application scenarios
With its high reliability, flexible protection function and easy production packaging, CXLE82135XJ is very suitable for the following applications:
·Medium and high power LED bulb, candle light
·Commercial lighting such as LED downlights and panel lights
·Outdoor or industrial LED lighting requiring open circuit protection
·Intelligent lamp system supporting wall switch color temperature adjustment or human body induction
VIII. Packaging and pin functions and ordering information
CXLE82135XJ adopts the classic DIP7 package with a standard pin spacing of 2.54mm, which is convenient to use on general brassboard or PCB, and is also suitable for manual welding and maintenance. The order model is CXLE82135XJ and the packaging form is tube packing, which is convenient for small batch procurement and engineering verification.
IX. Electrical characteristics
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Xi. Conclusion
CXLE82135XJ integrates high-precision constant current, flexible and adjustable protection, intelligent control interface and easy-to-produce packaging, providing a highly competitive solution for medium and high-power non-isolated LED lighting drivers. Its external OVP function gives designers greater flexibility, while the comprehensive protection mechanism ensures the high reliability of end products in various harsh environments.
JTM-IC has always been committed to providing high-performance and cost-effective power management chips for the global LED lighting industry through innovative technologies. For detailed technical documents, reference designs, or application samples of CXLE82135XJ, please visit the official website of JTM-IC:jtm-ic.com.
This article is provided by the JTM-IC technical team. Welcome to reprint it. Please specify the source fromjtm-ic.com.
