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12W LED Light Bulb Schematic

Schematic diagram of a 12w 220V LED light bulb made by Star Light:

Schematic diagram of a 12W LED light bulb
Fig. 1: Schematic diagram of the 12W LED light bulb

The heart of the circuit is a PT4554D high precision non-isolated step-down LED constant current IC. The IC has an integrated 500V power MOS and requires only a few peripheral components, which greatly saves system cost and size. It also offers comprehensive protection features such as LED short-circuit protection, over temperature drop current protection, etc.

The only active discrete components are the rectifier bridge and a diode. There are two high voltage electrolytic capacitors, one non-polarized capacitor on the AC line side, two inductors, one fusible resistor and a few surface mount resistors.

On a separate PCB connected through a connector you'll find 16 (double) LEDs connected in series, generating a bright, warm (3000K) light.

Disassembled LED bulb pictures

12W LED light bulb PCB back side
Fig. 2: 12W LED bulb PCB - back side
12W LED light bulb PCB component side
Fig. 3: 12W LED bulb PCBs - component side
Disassembled 12W LED light bulb
Fig. 4: The disassembled LED light bulb