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EN63A0 remote sense

MBaqu
Beginner
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Hello,

Is it possible to create a remote sense function using EN63A0 (perhaps by connecting feedback at the load)?

Regards

 

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31 Replies
Mostafa_Intel_AE
Employee
4,782 Views

Hello MBaqu,

Yes, you can implement the remote sensing using EN63A0 or any other Enpirion's regulator as shown below.

  1. The Ca branch and the Vsense pin must be connected at the last default output capacitor (Cout)
  2. Connect Ra branch at the load point to compensate for the voltage drop across the PCB
    • Make sure Ra placement is near to EN63A0 not near to the load side to avoid having a long trace for VFB pin (where it is so sensitive to the noise).

Capture.PNG

Thanks,

Mostafa

 

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MBaqu
Beginner
4,756 Views

Hello Mostafa,

1/ For the Vsense pin, we don't use it because we don't need the prebias feature, is it a problem?

2/ By connecting the Ra branch at the load point, how can I avoid any stability issue? Perhaps, using your stability tool anf adding trace RES and trace IND is sufficient but what about the parasitic capacitor of the trace?

Thanks

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Mostafa_Intel_AE
Employee
4,749 Views

Hello MBaqu,

No need to connect the VSENSE in your case since you don't use the pre-bias feature.

I only include that in my recommendation to make it general answer for any of Enpirion regulators.

 

Regarding the stability concern, based on the analysis that we did there is no worries in that connection where the control loop will not be effected.

Unfortunately the stability tool is not suitable for that analysis even if it shows that your system is stable where it always has Ra and Ca branches connected together at the same point and you can't separate them.

So i have attached EN63A0 LTSPICE (free spice tool from Analog devices, please click here to download) which will help you to do that analysis in time domain.

 

Thanks,

Mostafa

 

 

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MBaqu
Beginner
4,746 Views

Hello Mostafa,

Thanks, I'll make analisys based on simulation but is it possible to have a Pspice model because we are used to Pspice from Cadence and encrypted model from LTspice are not compatible.

Regard

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Mostafa_Intel_AE
Employee
4,740 Views

Hello MBaqu,

Sure, attached please find the pspice model of EN63A0 with a test example circuit.

Thanks,

Mostafa

 

 

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MBaqu
Beginner
4,733 Views

Thanks a lot Mustafa,

Can I ask you the same model for the EN6337?

Regards

 

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Mostafa_Intel_AE
Employee
4,728 Views

Hello MBaqu,

Attached please find the pspice model of EN6337.

Thanks,

Mostafa

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MBaqu
Beginner
4,647 Views

Hello Mostafa,

I have some issue running simulation with EN63A0. Running your test schematic, result are like image below :

MBaqu_0-1605869172283.png

If I replace input and output capacitors by ideal one (i.e. without ESL and ESR), simulation doesn't converge.

 

Could you help me please?

Final goal is to make stability simulation with long feedback track.

Thanks

 

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Mostafa_Intel_AE
Employee
4,634 Views

Hello MBaqu,

We don't recommend to use the ideal values but if you are facing Ltspice converge issue please adjust your LTSPICE setting as shown below.

Mostafa_Intel_AE_0-1605932678554.png

 

Regarding the stability simulation, i have updated the circuit to add AC analysis and the simulation result as below. you can adjust the circuit based on your actual component values

Mostafa_Intel_AE_1-1605932755921.png

Attached also is the simulation circuit with all the log and raw files, so you can have all same resulting and results as mine.

Thanks,

Mostafa

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MBaqu
Beginner
4,626 Views

Hello Mostafa,

My issue is related to the Spice model used with Pspice from Cadence not LTSpice.

We are familiar with Pspice so I prefer use it.

Thanks

 

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MBaqu
Beginner
4,622 Views

Hello,

 

Another question:

We use 3 EN63A0 in parallel. About the stability, do we need to add all capacitors on the Vout on the simulation or just total number of capacitors divied by 3?

Thanks

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MBaqu
Beginner
4,560 Views

Hello,

 

Any update about my last question.

In addition, is it possible to have the LTspice model of EN6337?

Thanks

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Mostafa_Intel_AE
Employee
4,550 Views

Hello MBaqu,

 

So sorry for late response.

Attached please find EN6337 LTSPICE model.

 

Regarding your question about the stability during the simulation when there are 3x EN63A0 connected in parallel:

Since the available simulation model doesn't support the parallel connection, then you can divided the total capacitance by 3 to make the equivalent system impedance close to what it looks like in actual life.

 

Thanks,

Mostafa

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MBaqu
Beginner
4,536 Views

Hello Mostafa,

I'm not able to simulate the EN6337 on Pspice or LTspice in AC mode in order to verify the stability.

In transient, all is OK but results in AC are very strange not like the EN63A0, could you help?

Thanks

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MBaqu
Beginner
4,527 Views

I made more test and all is like the model doesn't support AC simulation, any update?

Thanks

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Mostafa_Intel_AE
Employee
4,522 Views

Hello MBaqu,

 

I have reviewed the LTspice tool and it looks it is limited and can't find the DC operating point to do the AC analysis.

So the only way to fix that, i need to create a new model that only represent the regulator transfer function, and to build that will take time.

So to check the stability quickly, you can use the stability tool to do the loop calculation and use the DC ltspice model to validate that the time domain analysis looks stable and there is no oscillation.

 

Thanks,

Mostafa

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MBaqu
Beginner
4,516 Views

Ok, I will use the tool and the time domain.

Nevertheless, I'm interesting by the AC model when you will have build it.

Thanks

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MBaqu
Beginner
4,452 Views

Hello Mostafa,

First, I wish you an happy new year.

Could you give me an estimation time to build the Spice model (LTspice or Pspice) with AC behavior on the EN6337 component?

 

Thanks a lot

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MBaqu
Beginner
4,443 Views

Hello Mostafa,

More of that, I'm trying to correlate LTspice simulation with your Excel file using the EN63A0 component but I'm not able to have same result.

My LTSpice simulation is below:

MBaqu_0-1610635631518.png

Resut is phase margin around 90°C at 37KHz:

MBaqu_1-1610635708486.png

Same circuit with Excel tool, I add the same capacitor:

MBaqu_2-1610635792344.png

Resut is phase margin around 62°C at 71KHz, even the shape of the curve is different:

MBaqu_0-1610636256239.png

Could you help me, please?

Best Regards

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Mostafa_Intel_AE
Employee
4,139 Views

Hello @MBaqu ,

Happy new year to you too!

I trust more on the stability tool results, and i have created the AC model using PSPICE (OrCAD) as attached.

i have created a test circuit for the model so if you have OrCAD in your machine just open the .opj file and run the simulation from there.

Regarding the DC model: it is not good to do the small signal analysis with using the DC model because it is very hard for the simulation tool to get the steady state operating point so the tool can perform the small signal analysis.

So creating the small signal model as attached will help to do the stability analysis more accurate.

 

Thanks,

Mostafa

 

 

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