PT4557 is a high precision non-isolated step-down LED constant current driver chip. The chip works in quasi-resonant mode and is suitable for non-isolated step-down LED constant current power supply with a full range of input voltage from 85Vac to 265Vac.

PT4557 integrates a rectifier bridge stack, 500V power MOS, high-voltage power supply circuit, freewheeling diode and sampling circuit on a single chip, without start-up resistors and VDD capacitors, the system only needs few peripheral components, which greatly saves system costs and volume.

The PT4557 adopts a high-reliability constant current control method to achieve excellent linear regulation, load regulation and temperature characteristics. The output current mass production deviation is within +/-5%.

PT4557 provides complete protection functions: including LED short-circuit protection and over-temperature drop current protection.

PT4557 is packaged in ASOP-7 and other packages.

main feature

? High-voltage single-chip integrated 500V power tube, high stability

? Internally integrated freewheeling diode

? Internal integrated rectifier bridge stack

? No startup resistor and VDD capacitor required

? Inductor current quasi-resonant mode (QR) to reduce switching losses

? Efficiency up to 93%_

? +/-5% current accuracy

? Excellent line regulation, load regulation and temperature characteristics

? LED short circuit protection

? Over temperature drop current protection

? Adopt ASOP-7 and other package forms

main application

? LED candle light, bulb light

? LED downlights, fluorescent lamps

? Other LED lighting