LM3530: OVP pin has 0 V

Mahdi Khalili

Part Number: LM3530

Hi,

I used the LM3530 for my display LED driver. I produced 8 pieces and 2 of them working fine. In other 6 PCB, I have the same voltage from SW pin to OVP. On normal PCB, the OVP pin voltage is 40V. But here I measure the same voltage as SW pin. Is there any possibility for OVP pin to have 0 Volts? Or it is just these PCBs are damaged or the OVP pin doesn't have good contact to the PCB.

Thanks

over 2 years ago

0 Mason Wang over 2 years ago

TI__Genius 9630 points

hi Mahdi

What is your operation condition, Vled? Iled?

The min. OVP threshold is 40V, from your description OVP is triggered, please confirm.

Besides, in mentioned abnormal PCB, you mentioned "measure the same voltage as SW pin", do you mean Vsw=40V? It would be helpful to provide waveforms of SW, OVP, LED current.

0 Mahdi Khalili over 2 years ago in reply to Mason Wang

Prodigy 55 points

Hi, I use Iled. The voltage on the OVP is about 3.3 Volt. same as the input voltage. There is a possibility that during the fabrication, the enable pin isn't correctly connected to the board. Because it has a Via in pad. If the enable pin is not connected, can it have the same condition as I see?

+1 Mason Wang over 2 years ago in reply to Mahdi Khalili

TI__Genius 9630 points

From you description, voltage of OVP is same as input voltage, This means the device does not work and input voltage directly go through to output side. So it is possible that enable pin is not properly pulled up due to what you mentioned connection issue and device cannot work normally.

0 Mahdi Khalili over 2 years ago in reply to Mason Wang

Prodigy 55 points

Thanks. I sent back the PCBs to supplier and will inform here about the results.

0 Mason Wang over 2 years ago in reply to Mahdi Khalili

TI__Genius 9630 points

OK, feel free to discuss here.

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LM3530: OVP pin has 0 V