Rectifier and EMI filter for multiple led drivers

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Thread Starter

Teddy Doloir

Joined Feb 9, 2019
I try to make a power supply stage for 2 offline led drivers insted of making 2 different boards. Find in atteched file the design A and B. Could you explain and suggest me what is the best design to follow ?



Joined Jul 11, 2016
since the transformers are !usually! not too expensive the option A
(-1-) you'll loose only one OUTP shoulder at output fault
(-2-) you have lesser voltage drop on rectifier diodes
(-3-) you can use lower power transformers = lower reactance line filters

IF the LED-s are cheap and won't consume too much power the Opt. B would likely be more compact

+ you should in either case limit the inrush currents to transformers and/or to filter capacitors (at startup)
IF your rectifier bridges have parallel protection resistors to diodes you should protect the filter caps from "AC" at no load condition


Joined Feb 24, 2006
You have the transformer shown incorrectly. Wired this way is unsafe, hazardous, and potentially fatal. As such it violates the TOS for this site.

Thread Starter

Teddy Doloir

Joined Feb 9, 2019
Yes i know it is unsafe , but the HV9961 led driver can run with a rectified main voltage. The transformers are choke common mode used as EMI filters, not for voltage isolation.


Joined Aug 23, 2012
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