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18 - 200 V dc input / 12 V @10-30mA ouput / Topology: Buck

Posted by: HansPferd on

Hello Support,

I want to create a buck converter from 18 to 200 Vdc input voltage.
Now I found your TopSwitch Family which can start from a voltage about 18 V.

My question right now is: Can I use one of the TopSwitches in a buck topology?
When I can use it as a buck converter, where can I find some application notes or something else to design my buck converter?
Where can I find calculations, so that the design would work?

Thank you very much.

Regards,
Hans

Comments

Submitted by VCastrellon on 01/06/2011

Hans:
When you have a buck converter design. the output voltage is in series with the Topswitch. So if you have 18 volts input and 12 v output, the controller will have only 6 volts from DRAIN to SOURCE. Your input voltage is too low for the TOPswitch to work. If you can increase your minimum Vin to about 30 Volts, It may be possible to design a solution.

Submitted by HansPferd on 01/07/2011

Hello,

thanks for the answer.

If I change the input and output voltage, lets say to:
Input: 23 - 200 V
Ouput: 5V
then I have a D-S-Voltage from around 18 V. Would it work within these changes?

Regards,
Hans

Submitted by HansPferd on 01/11/2011

Hello support,

I have another question.
If I adjust voltage range, I may use TOPSwitch in a buck converter topology.
If we assume that input voltage starts at 30 V and output stays at 12V @10-30 mA, it will works.
With this fixed voltage range I have another problem:
How do I have to connect control pin? Can I do it as you did in your application note an37 (a direct feedback resistor network)?
Or do I have to consider something else? A special compensation network, for e.g.
How does it look like, if I have to use a compensation network?

Thank you for helping me.

Regards,
Hans