Time to ask a question...
I have recently obtained some 5W LED lamp circuit boards.
They are "COB" - chip on board. Built on aluminum backed printed circuit boards.
I was skeptical at first, so connected them via an isolation transformer using a low current fuse in the circuit.
But they work very well, direct from a 240VAC supply. They have very few components on the board: a bridge rectifier, a couple of SMT resistors and a mystery integrated circuit. No inductors or capacitors.
What I want to know is: how does it work? What is the operating principal? Presumably not switchmode because there are no energy storage components. I realise the COB led is actually a lot of LEDs - about 24 I think. So in series that's about 72V. But how is the 240V dropped to this level? Or are they only switched on during the part of the cycle when the voltage is approximately this level?
Surely that would be a very low duty cycle?
Anyone got any data on the mystery IC?
Picture attached.
I have recently obtained some 5W LED lamp circuit boards.
They are "COB" - chip on board. Built on aluminum backed printed circuit boards.
I was skeptical at first, so connected them via an isolation transformer using a low current fuse in the circuit.
But they work very well, direct from a 240VAC supply. They have very few components on the board: a bridge rectifier, a couple of SMT resistors and a mystery integrated circuit. No inductors or capacitors.
What I want to know is: how does it work? What is the operating principal? Presumably not switchmode because there are no energy storage components. I realise the COB led is actually a lot of LEDs - about 24 I think. So in series that's about 72V. But how is the 240V dropped to this level? Or are they only switched on during the part of the cycle when the voltage is approximately this level?
Surely that would be a very low duty cycle?
Anyone got any data on the mystery IC?
Picture attached.