Contact: Nie Zhihui 13632552696 WeChat: 13632552696

PT4554C overview:

PT4554C is a high precision non-isolated step-down LED constant current driver chip. The chip works in quasi-resonant mode, suitable for the full range of 85Vac~265Vac

Input voltage non-isolated step-down LED constant current power supply.

PT4554C integrates 500V power MOS, high-voltage power supply circuit and sampling circuit on a single chip, without starting resistor and VDD capacitor, the system only needs

Few peripheral components are required, 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. Output current mass production deviation

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

PT4554C 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

PT4554C package: support SOT33-4, SOP-7 and other packages

PT4554C application:

LED candle light, bulb light

LED downlight, fluorescent light

Other LED lighting

PT4554C function description:

PT4554C is a constant current driver chip dedicated to LED lighting, which is used in non-isolated step-down LED driver power. The 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.

Startup and VDD Capacitors

After the system is powered on, 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, output current setting

The 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 compared with the internal 500mV threshold voltage. When the CS voltage reaches the internal detection threshold, the power tube is turned off.

Multiple protection functions

The PT4554C has built-in multiple protection functions, including LED short-circuit protection. When the LED is short-circuited, the system works at a low frequency of 2-4KHz, and the CS turn-off threshold is reduced by about half, so the power consumption is very low. Once an abnormal situation occurs, the fast detection circuit inside the chip will trigger the protection logic, and the system will immediately stop the switching operation, thereby ensuring the safe operation of the system.