CXLE8434XH is a constant current driver chip designed specifically for isolated LED lighting. It adopts a flyback topology structure and supports a full range of input voltages from 65Vac to 265Vac. The chip integrates a 650V high-voltage power MOSFET and adopts high-voltage JFET power supply technology and gate demagnetization detection technology, without the need for external VCC capacitors and starting resistors, greatly simplifying peripheral circuits and reducing system costs and volume.
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[ CXLE8434XH ]"
In LED lighting systems, the stability, safety, and energy efficiency of the driving power supply directly affect the overall performance and lifespan. JTM-IC launches a solution to meet the demand for low to medium power isolated LED lightingCXLE8434XH— — A high-precision flyback LED constant current driver chip, with its high integration, no need for VCC capacitors, full voltage input, and multiple protections, has become an ideal choice for applications such as bulb lights and tube lights. This article will provide a comprehensive interpretation of CXLE8434XH from multiple dimensions, including technical features, working principles, and design recommendations, to assist engineers in achieving more reliable and efficient lighting designs.
1、 Chip Overview: Isolation flyback, high integration design
CXLE8434XH is a constant current driver chip designed specifically for isolated LED lighting. It adopts a flyback topology structure and supports a full range of input voltages from 65Vac to 265Vac. The chip integrates a 650V high-voltage power MOSFET and adopts high-voltage JFET power supply technology and gate demagnetization detection technology, without the need for external VCC capacitors and starting resistors, greatly simplifying peripheral circuits and reducing system costs and volume.
2、 Core features and advantages
2.1. Highly integrated and simplified designNo need for VCC capacitors, starting resistors, or auxiliary windings, resulting in extremely low BOM costs.
2.2. Accurate constant current output：± 5% LED output current accuracy ensures consistent lighting brightness and long-term stability.
2.3. Comprehensive protection mechanismIntegrated LED short-circuit/open circuit protection, chip power supply undervoltage protection, and overheat regulation function, with high system reliability.
2.4. EN control functionSupport enable control for easy dimming or intelligent control integration.
2.5. Wide voltage inputAdapt to global grid voltage and have strong universality in design.
3、 Typical application scenarios
CXLE8434XH is suitable for various low to medium power isolated LED lighting devices, such as:
· LED bulb light
· LED downlight
· Indoor lighting such as panel lights and ceiling lights
4、 Key Electrical Parameters and Selection Guidelines
Under typical conditions of TA=25 ℃, the main parameters of CXLE8434XH are as follows:
| parameter | condition | typical value | unit |
|---|---|---|---|
| Input voltage range | AC input | 65– two hundred and sixty-five | Vac |
| Output power (230V+ 15%) | CH/DH/EH version | ≤9/12/15 | W |
| operating frequency | Normal Mode | 65– seventy | kHz |
| Current detection threshold VCS-TH | Constant current control point | four hundred | mV |
| Power transistor on resistance RDD_ON | DH version, VGS=10V | four point seven | Ω |
| Overheating regulation temperature TREG | Chip surface | one hundred and forty | ℃ |
| boxed type | - | SOP7 | - |
The chip offers three versions: CH, DH, and EH, corresponding to different power levels and on resistance. Users can flexibly choose according to their output power requirements.
5、 Deep analysis of working principle
5.1. Start up and power supply
After the system is powered on, the internal high-voltage JFET directly takes power from the HV pin to charge the internal VCC capacitor. When the voltage reaches the start-up threshold, the control circuit begins to operate. During normal operation, JFET continuously supplies power to the chip without the need for auxiliary windings.
5.2. Constant current control mechanism
The chip operates in inductor current discontinuous mode (DCM), detecting the peak current of the transformer's primary side through the CS pin and comparing it with the internal 400mV threshold. When the CS voltage reaches the threshold, the power transistor is turned off to achieve cycle by cycle peak current control.
Calculation formula for peak current on the primary side:
The output LED current is determined by the transformer turns ratio:
Among them, RCS; For external sampling resistors, NP And NS They are the number of turns on the primary and secondary sides respectively.
5.3. Frequency and demagnetization control
The system defaults to working at 65kHz; 70kHz， The frequency can be adjusted through the inductance and turn ratio of the transformer. The chip is equipped with demagnetization detection to ensure the reset of the transformer core and avoid saturation.
6、 Detailed explanation of comprehensive protection function
6.1. LED open circuit protectionWhen an open circuit occurs, the system triggers OVP and locks it, and automatically resets and restarts after 10ms.
6.2. LED short circuit protectionWhen short circuited, the chip enters low-frequency mode (about 3.3kHz) with extremely low power consumption.
6.3. Overheating regulationWhen the junction temperature exceeds 140 ℃, gradually reduce the output current and control the temperature rise.
6.4. Overvoltage protection (OVP) settingThe protection voltage point can be set through the ROVP external resistor, and the formula is as follows:
Among them, TOVP; Determined by transformer parameters and preset OVP voltage.
6.5. EN controlThe ROVP pin also has an enable function, with voltage>0.3V turning on and<0.1V turning off the output.
7、 Key recommendations for PCB layout
A good layout is the foundation for ensuring stability and low EMI:
· Ground wire designThe ground wire of the current sampling resistor should be short and thick, and connected to the bus capacitor ground at a single point with the chip ground.
· Minimize power loopReduce the loop area of the transformer's primary side power transistor absorption circuit and secondary side diode output capacitor.
· Heat dissipation treatmentThe auxiliary copper area of the DRAIN pin should be sufficient to improve heat dissipation performance.
· NC pinKeep suspended and ensure that the creepage distance meets safety requirements.
· ROVP routingStay away from high-voltage noise sources to avoid accidental triggering.
8、 Why choose CXLE8434XH?
· Minimalist peripheral designEliminating VCC capacitors, starting resistors, and auxiliary windings reduces system costs and volume.
· high reliabilityFull protection mechanism+overheating regulation, suitable for complex working environments.
· Flexible designSupport EN control and external OVP adjustment for easy function expansion.
· Strong compatibilitySOP7 packaging, suitable for automated surface mounting, compatible with standard PCB processes.
9、 Extension application and selection suggestions
For higher power or non isolated requirements, reference can be made to other star products under JTM-IC, such as:
· CXLE83183B/CXLE83184CRNon isolated step-down PFC driver chip, suitable for LED tubes, bulb lights, etc. that do not require isolation.
· For more models, please visit the official website;jtm-ic.com query
10、 Packaging and Pin Function
11Related products; more...
12、 Conclusion
CXLE8434XH provides high-quality driving solutions for low to medium power isolated LED lighting due to its high integration, high precision, and high reliability. JTM-IC always focuses on innovation and optimization of power management chips, providing customers with a full process service from chip selection, design support to batch delivery. For complete data manuals, reference designs, or sample applications, please visit;jtm-ic.comJoin us in promoting the development of intelligent lighting technology.
