Dissipation in damper circuit of Triac dimmable ~10W light bulb
Hello,
As you know, all triac dimmable, switch mode led light bulbs need damper circuits so that the triac's violent switching dont damage the components.
What dissipation is typical in the damper circuits of say a 10W led light bulb circuit?
If a led bulb was not meant for triac dimming, then really, as you know, it still needs the protection, as it may accidentally be connected to a triac dimmer. In this case, would you recommend instead, a simple potential divider and comparator and series FET which literally switched the led driver circuit out of the mains for the duration of the high voltage transient due to the triac dimmer?
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Thanks,
2W sounds like an appalling amount of wasted power for a 10W bulb..of course, I appreciate that this is in all bulbs, and not just powerint ones.
Supposing that the bulb of DER350 is connected to a mains supply with no wall dimmer, then how much dissipation (if any) would you expect in the damping resistor , R8?
Hi,
The damper resistor in DER-350 is directly proportional to the product of input RMS current and the conduction resistance of the MOSFET (Q1). Approximated loss is less than a quarter watt at non dimming operation.
Highest lost occurs at 90 degree conduction of the TRIAC, always consider this condition and evaluation in your design.
During dimming, the power loss is higher as compared to the non-dimming operation.
Regards,
PI-Jono
Hi,
The power dissipation in a damper resistor is around 2 to 3W depending on the total input capaciance and operating input voltage. You are correct, you need a proper power management for this scenario. Plese refer to this reference design as an example in minimizing the power loss in a cheaper way than using a comparator.
http://www.powerint.com/sites/default/files/PDFFiles/der353.pdf
or by:
http://www.powerint.com/sites/default/files/PDFFiles/der350.pdf
Regards,
PI-Jono