LM7310: About OVOL Operation

Hi Ryu,

Can you please share schematic. What is the output capacitance value?

Best Regards,

Rakesh

Hi Rakesh,

Thanks for the reply.
Sorry I forgot to tell you.
This one is using EVM's U2.
J9 is connecting 2 and 3.

Sincerely.
Ryu

Hi Ryu,

Please add a 10uf cap at input and repeat the test. What is the load at output?

Regards

Kunal Goel

Hi Kunal,

Thanks for the reply.
What is the reason why adding an input capacitor would be better?
I tried the output load with 40 ohms electronic load and 40 ohms resistor respectively and the result was the same.

Sincerely.
Ryu

Hi Ryu,

I am thinking that transients on VIN and VOUT pin maybe causing something. Using cap will suppress those transients. Also please check if without the load you are seeing the issue? Please share waveforms also.

Regards

Kunal Goel

Hi Kunal,

Thanks for the reply.
It worked correctly when an input capacitor was added or no load was applied.
Thank you very much.
However, I do not know what principle solved the problem.
I would like to know.

Sincerely.
Ryu

Hi Ryu,

Please share waveforms showing VIN,VOUT,IIN,OVLO pin at zoomed out and zoomed in settings. I can comment more after looking at waveforms.

Regards

Kunal Goel

Hi Kunal,

Thanks for the reply.
What is IINpin?
Also, do you think that continuing to pull in constant current mode with an electronic load would cause problems?

Hi RYU,

IIN means input current to device. We don't recommend CC mode for current limit test. It may not be a problem during OVLO test. While you are doing test device is in current limit?

Regards

Kunal Goel

Hi Kunal,

Thanks for the reply.
It is not in a current limiting state.
When I increased the current value (1.5A), the same problem appeared again, but the problem improved when I increased the input capacitor.
Are there any design standards for input capacitors?

Sincerely.
Ryu

Hi Ryu,

You mean recommended value of input cap?

Regards

Kunal Goel

Hi Kunal,

That is correct.
Please let me know if there is any difference depending on voltage or current.

Sincerely.
Ryu

Hi Ryu,

Let me check and get back.

Regards

Kunal Goel

Hi Kunal,

Thanks for the reply.
I'll be waiting to hear from you.

Sincerely.
Ryu

Hi Kunal,

How are things?
I'll be waiting to hear from you.

Sincerely.
Ryu

Hi Ryu,

We generally recommend 1uf at input and output to suppress transient. But in your case may be wire length is large so large inductance so more cap is needed to suppress transient. I think transients are happening in your evaluation at input and output which is causing device to misbehave at low cap.

Regards

Kunal Goel

Hi Kunal,

Thanks for the reply.
OVLO is known to stop working under the following conditions
The problem disappears when the capacitance of the Vin capacitor is increased.

When the voltage of Vin is high
When the load current is high.
When the output slew rate is too fast

I understand the recommended value, but is there a limit to the capacitor capacitance?

Sincerely.
Ryu

Hi Ryu,

From our device working there is no limit. It is decided based on application and system. Is high cap a issue for customer?

Regards

Kunal Goel