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2022-09-24 22:26:30
PT4218 non-isolated single-stage active PFCLED constant current control chip
Overview
PT4218 is a high-precision step-down LED constant current control chip with active power factor correction, suitable for non-isolated LED constant current power supply with full voltage input range of 85Vac-265Vac. The controller integrates an active power factor correction circuit to achieve high power factor and low total harmonic distortion. Because of working in the critical conduction mode of the inductor current, the power MOS tube is in a zero-current turn-on state, the switching loss is reduced, and the utilization rate of the inductor is also high.
The PT4218 adopts a unique current sampling and constant current control mechanism, and has excellent line voltage regulation, load regulation and output current temperature characteristics.
PT4218 provides complete protection functions: including LED short-circuit/open-circuit protection, cycle-by-cycle current limiting protection, inductor winding short-circuit protection, etc. All protection states have an 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.
Features
? ±3%_LED output current accuracy
? Fixed on-time, high PF value (>0.9)
? allow