AN3256 is a ST application note that introduces a prototype of a non-dimmable, non-isolated LED driver. The physical design is small enough to fit in the base of an A19 lamp (screw bases 40 to 60 W equivalent). The coupled inductor has a stepdown winding to power the L6562A PFC driver. The design goals: Input: 96-132VAC, 60 Hz, non-dimmable, TRIAC dimmer safe (no damage); Output: 370 mA into strings of 5 to 12 LEDs; Topology: stepdown (buck) switching regulator; Features: regulation of LED current, power factor acceptable for US market for residential use, excellent efficiency. ST devices: PFC controller: L6562A; Switching FET: STD5NM50; Flywheel diode: STTH1R04.
The document details a stepdown (buck) switching regulator design intended for use with strings of 5 to 12 LEDs. The circuit utilizes the L6562A PFC controller and STDS5NM50 switching FET, featuring regulation of LED current and acceptable power factor for US residential use.
| Input Voltage Range | 96-132VAC, 60 Hz |
|---|---|
| Output Current | 370 mA |
| Topology | stepdown (buck) switching regulator |
| PFC Controller Device | L6562A |
| Switching FET Device | STDS5NM50 |
The circuit stops operating and flashes at a line voltage of 88 V.
No, the design is non-dimmable and TRIAC dimmer safe without damage but does not support dimming.
No, the document notes that the circuit is not capable of providing output open circuit protection.