LM25011AMYE

Hello, Can you provide the schematic you utilized for your evaluation of the product?

In addition, do you have any waveforms to provide? I would like to see Vin voltage, SW voltage, and Vout voltage.

483_2021_V11_COMUS.pdf

this the schema for the power parts.

for signal it is not easy.

all parts are under the capacitor for 22mF .

Thanks, I hope to follow up with you on the review, Monday.

not quite like this.

when the output capacitor is discharged , the regulator works properly. Charge the capacitor to 8V, drive the coil all perfect.

I turn off power, no input voltage 0V , but the output capacitor has some voltage. if I turn on power input, if the output voltage is over 2V the IC do not restart.

the capacitor is 22000uF 0,022F 

it is more clear? this problem is only for LM25011AMYE , it works properly with  LM25011MY/NOPB

order the "A" version because waiting a lot of months and not get the normal parts.

Thank you for your help.

Oh, I see.

It seems like you are suggesting that the device does not start with pre-biased output.

I will see if we have encountered issues with pre-biased output on this architecture. From the datasheet alone and my understanding of the device, I do not see what would cause pre-biased output startup issues.

Allow me to get back to you.

Hello,

Can you please provide waveforms of Vin, Vout, and inductor current during the failure?

I will need to take a look if my understanding is correct to diagnosis the issue.

Vin and Vout no problem but how do you measure the inductor coil???? it is SMD and I do not have a device to read this. 

in the datasheet for the version "A" 

1) The LM25011A has a shorter minimum off-time than the LM25011

I do not think it is a problem

2) "Ripple voltage, which is required at the input of the regulation comparator for proper output regulation, is generated internally in the LM25011, and externally when the LM25011A is used." 

Not sure what it means but if must be externally , I do not have done?

3) "When the LM25011 operates in current limit, the on-time is reduced by approximately 40% (this feature is not present in LM25011A)."

What does this feature?

Hello, you could consider adding a series resistance and measure the voltage across it differentially to examine inductor current. It maybe a bit difficult without a clip-on current probe.

You can then measure Vin, Vsw, Vout, iL.

Maybe you can connect some leads to the capacitor to allow for easier measurement, as I understand the issue with board assembly.

2. The device requires ripple injection for stability. From your description, it does not seem to be the problem, but I can address the concern as well. The non-A version has the ripple injection needed for the COT architecture stability, emulated, internally, thus no need for additional circuitry.

See section 8.2.2 Output Ripple Control

3. The device has current limit, though, the on-time is not reduced. It will continue to operate at constant on time with peak current limit engaged.

ok thank you. 

1) measure current I will see but resistor is not one option  in serie with the coil, will try to see current on the power line because it is only the LM25011A to use current in the start up. 

2) ripple injection.

well, it is easy to solder these 2 cap and resistor for testing but if the output is not active the ripple circuit will have not to effect?! 

3) I will use a diode series with the capacitor of 22mF to see if it is my problem perhaps I can get the same problem with LM25011 for special situations.

we have not produced a lot of board it was a long design. først we try with a 5V capacitor with 33mF but the coil need 6V and the power on it was too low.

We have made 200 pieces with LM25011 and now only 12 of 100 with LM25011A ( stop production after testing the first panel). 

1) I think you will run into issues measuring the AC input current. It is supported by the caps. You maybe able to squeeze in power sense resistor in series with the output inductor, with positioning them at an angle.

2) the ripple injection ensures stability across Vin range, as well output loading. 

3). I am unsure that I am following your suggested debugging step. Maybe you can provide an illustration?

i hope you can see the new diode. I will try this week end. 

Hello Thierry, 

Let us know when you try restarting the circuit with the diode. 

Regards, 

Denislav

YOU WILL GET SOME INFO MONDAY. 

great, thanks.

Test with a serie diode like the picture you get.

it is working, well I must see more because I feeling it is slow. But I do not believe i feeling in electronics I will make some measure to see. 

but the problem was the voltage on the out capacitor with the LM25011A 

Good to hear. Let me know if additional support is needed.