LM20323 spice model for TINA-V9 ...

Hi Nikhil,

thanks very much.

Best Reagrds,

Gabriele

I have tried the new LM20333 model but in this model is not possible to set the switching frequency.

How do I proceed?

Is there another compatible model ?

Gabriele

Gabriele,

Are you trying to use the SYNC pin to set the frequency?

> Are you trying to use the SYNC pin to set the frequency?

No, I have not tried. I have to drive this pin with an external clock ?

Gabriele

Gabriele,

My question as related to how you are trying to modify the frequency? If you leave SYNC floating this device operates at fixed 200KHz. Are you asking for an alternate part that allows you to change the frequency of the device (possibly by connecting an external resistor to a pin)?

I have the LM20343 that not have the Spice Model. You have advised me to use LM20333 to perform simulations but LM20333 always operates at 200 KHz although fits a square wave signal (0V Low - High 2V) with frequency of 1MHz on the SYNC pin.

How can I simulate the frequency of 1000 kHz ?

Thanks.

Gabriele

Gabriele,

I am sorry but LM20333 does not have an RT pin to set the frequency like LM20343. Using the SYNC pin may not help you since you will need to generate an external clock to synchronize the power supply to (which you may or may not have). I think it would be the quickest for you to use WEBENCH Designer to create your design and simulate it within WEBENCH itself. I have create a sample design that can operate at 1MHz. Have a look and let me know if you have any issues.

webench.ti.com/.../SDP.cgi

Thanks for your help.

I do not really like "WEBENCH Designer" especially because of very different results from excel sheets for the same chip. I had several problems with the values calculated using "WEBENCH Designer" so I prefer not to use it.

Maybe it would be appropriate to change the Lm20333 model and enter the frequency as a parameter does not believe?

I'll do some more testing.

Thanks very much.

debugasm

Gabriele,

The excel sheet gives a particular design for your specifications, but there can be several alternatives for the same specifications. It just depends on what you want to tune your design for. WEBENCH provides many more options than a static spreadsheet, with real world BOM, pricing, availability, ability to do electrical and thermal simulations, and also export your schematics and PCB to popular CAD formats for prototyping. This is not available in the excel calculator.

You mentioned you had several problems with the WEBENCH calculated values. Can you elaborate on what the issue was so that we can look into it?

Thanks,