1 Scheme name: China Resources Silicon Power PT4554C province VCC non-isolated constant current drive scheme, with OVP protection, within 18W

2 Brand name: China Resources Siwei

3 Overview: PT4554C 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. PT4554C integrates 500V power MOS, high-voltage power supply circuit and sampling circuit on a single chip, without start-up resistor and VDD capacitor, the system only needs few peripheral components, which greatly saves system cost and volume. The PT4554C 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 +/-3%. PT4554C provides complete protection functions: including LED short-circuit protection and over-temperature drop current protection.

PT4554C adopts SOT33-4, SOP-7 and other packages

3 program features:

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

No Startup Resistor and VDD Capacitor Required

Quasi-Resonant Mode (QR) of Inductor Current to Reduce Switching Losses

Efficiency up to 93%_+/-3% current accuracy

Excellent line regulation, load regulation and temperature characteristics

LED short circuit protection

Over temperature drop current protection

4 Applications:

LED candle light, bulb light

LED downlight, fluorescent light

Other LED lighting

5 Function description: PT4554C is a constant current driver chip dedicated to LED lighting, which is used in non-isolated step-down LED driver power. A 500V power switch is integrated inside the chip, which can achieve excellent constant current characteristics with only a few external components. And no auxiliary winding power supply and detection is required, and the system cost is extremely low. After startup and power-on of the VDD capacitor system, the bus voltage supplies power to the internal VDD module through the HV pin, and the PT4554C has a built-in voltage regulator to clamp the VDD voltage. When the chip is working normally, the required VDD current is extremely low, so there is no need for auxiliary winding power supply. Therefore, no external capacitor is required for VDD, which reduces peripheral components and costs. Constant current control, the output current setting chip detects the peak current of the inductor cycle by cycle. The CS terminal is connected to the input terminal of the internal peak current comparator, and is compared with the internal 500mV threshold voltage. When the CS voltage reaches the internal detection threshold, the power tube is turned off. break.