Contact: Nie Zhihui 13632552696 WeChat: 13632552696

Overview:

PT4238E/PT4240E is a high-precision step-down LED constant current driver chip with active power factor correction, suitable for non-isolated LED constant current power supply with full voltage input range of 85Vac-265Vac. The PT4238E/PT4240E work in the critical conduction mode of the inductor current, the power MOS tube is in the zero-current turn-on state, the switching loss is reduced, and the utilization rate of the inductor is also high.

PT4238E/PT4240E adopts a unique current sampling and constant current control mechanism, with excellent line voltage regulation, load regulation and output power.

Flow temperature characteristics.

PT4238E/PT4240E provide complete protection functions: including LED short circuit/open circuit protection, cycle-by-cycle current limiting protection, etc. All protection states have automatic restart function. The unique over-temperature regulation function enables the system to automatically reduce the current when the temperature is high to effectively protect the power supply and load. In addition, the chip has a built-in soft-start circuit, which can effectively reduce the power-on stress of the switch tube and LED lamp beads.

PT4238E/PT4240E support SOP-7 package.

Features:

? Built-in high voltage JFET for fast startup and power supply

? Built-in high voltage MOSFET

? Fixed on-time, high PF value (>0.9)

? ±3%_LED output current accuracy

? Quasi-resonant control mode

? Up to 95% conversion efficiency

? Excellent line regulation and load regulation

? Excellent current temperature compensation characteristics

? Soft start function

? LED short/open protection

? Cycle-by-cycle current limit

? Over temperature drop current function

application:

? LED bulbs, spotlights

? LED PAR30, PAR38 lamps

? LED fluorescent lamp

? Other LED lighting

Function description:

PT4238E/PT4240E is a high-precision step-down LED constant current driver chip with active power factor correction, suitable for non-isolated LED constant current power supply with full voltage input range of 85Vac-265Vac. At the same time, it has the characteristics of high precision, high power factor, low harmonic distortion and high efficiency.

start up:

After the system is powered on, the bus voltage charges the VCC capacitor through the internal high-voltage startup and power supply circuit. When the VCC voltage reaches the VCC working voltage, the chip starts to work, the system transfers the input energy to the output through the inductor, and the output voltage begins to rise. Due to the use of soft-start technology, PT4238E/PT4240E can effectively avoid output current overshoot.