LM25017: Issue to use LM25017 for DALI power Supply

Davide Dalla Valle

Other Parts Discussed in Thread: LM25017

Hi,

We have design a schematic with LM25017 with 24VDC input 3W ( Meanwell IRM 03 -24 ) and we set the feedback resistor to have 16V out.

We set Fsw at 890Khz with 200K at RDON pin.

We set UVLO to 20VDc.

So, we use 16Vout for DALI Power supply with a current limiting circuit at 150mA.

So, when we do a short circuit in the DALI line, the LM25017 broken and we don't understand what's wrong.

We test the current limiting circuit with an external 16Vout and it's work well, if we use a LM25017 it's broken when DALI line is shorted.

I attached a schematic of power supply and a limiting circuit.

Thank you for your support.

over 6 years ago

0 Davide Dalla Valle over 6 years ago

Prodigy 50 points

Q2 is a wrong schematic component, we use a channel P mosfet FDD4243. Sorry..

0 Frank De Stasi over 6 years ago in reply to Davide Dalla Valle

TI__Guru 72685 points

Can you give more detail as to what you are seeing when you apply the load.
Does the system function correctly with the normal load?
Do you have switch and Vout wave-forms during normal and abnormal behavior?
What is the value of your inductor?

0 Davide Dalla Valle over 6 years ago in reply to Frank De Stasi

Prodigy 50 points

Hi and thank you so much for you reply.
So, the system fucntion correctly, we load a 16Vout with resistor load to have 170mA and it is ok. We check the switch pin and it's work fine. The inductor is a 33uH transforme 1:1

0 Frank De Stasi over 6 years ago in reply to Davide Dalla Valle

TI__Guru 72685 points

So, when you short the output of the current limit it is OK ??

When you short the output of the LM25017 it is not OK??

0 Davide Dalla Valle over 6 years ago in reply to Frank De Stasi

Prodigy 50 points

Hi, we have resolve the problem. The problem is the diode for VCC from Vout, when we short bus DALI, probably damage the internal regulator.

So, during the test we see that Vref of feedback isn't 1.225V but is 1.25V and this difference is very important for Vout.

Thank you so much for the support.

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LM25017: Issue to use LM25017 for DALI power Supply