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LM3447-A19-120VEVM: Output current inconsistency with dimmer(Max setting) and switch.

Part Number: LM3447-A19-120VEVM
Other Parts Discussed in Thread: LM3447

Hello, 

I am testing the LM3447-A19-120VEVM evaluation board to check the performance with different triacs. The IC works well but has a one major issue which I am trying to resolve.

--> There is a mismatch of output current when the driver is connected to switch and a Triac dimmer at its max setting.(~28% difference).

As noted on in Data sheet of LM3447 page 19( image attached), there is feature which should keep the Vdim command to be set to 1V after a certain max phase angle of dimmer to ensure the consistent output current.

But during the tests I observed that the V_FLT2 for dimmers is not reaching close to 1.45V and hence stays in the linear region of the curve, however, when no dimmer is connected, it reached close to 1.47V which ensures that Vdim is held constant.

Therefore, I want to understand what could be done to make the driver more consistent in terms of output current delivery when Triac Dimmer and a switch is connected.

Please note: I am using several famous Triac Dimmer used in US such as Lutron, Control 4, Leviton and this mismatch is with every dimmer.

Regards,

Ketan

Page 19 Curve of datasheet