How to increase the voltage by using CS5173?

[ling1995]

Hello~all,thanks for taking time to read my thread. I'm in hot water now,Can anybody here help me out?
Please look at the following picture,I would like to rise the voltage from 24V to 36V. And I did it according to the datasheet of CS5173. However,the chip always burned out ! I can’t understand what occurred ? Does anyone know ?Are the two parts in the picture of 22uH coupling transformers? Or they are absolute inductance?

Thank you in advance!
Wishes~

 

[lewando]

Per the datasheet that you have referenced, the absolute maximum rating of Vcc is 35 V. You can exceed that at your peril. Never operate at the absolute maximum rating. All test conditions in the datasheet indicate a 30 V maximum, that is probably a good maximum operating point for long term reliability.

Those dots are for reference when using coupled inductors. If the 2 inductors are coupled, then the polarity dots should be observed. If not coupled then it does not matter.

 

[CWatters]

Put a few diodes or zenner in series with VCC before the capacitor?

 

[davenn]

I would like to rise the voltage from 24V to 36V.

which voltage ?

 

[ling1995]

Per the datasheet that you have referenced, the absolute maximum rating of Vcc is 35 V. You can exceed that at your peril. Never operate at the absolute maximum rating. All test conditions in the datasheet indicate a 30 V maximum, that is probably a good maximum operating point for long term reliability.

Those dots are for reference when using coupled inductors. If the 2 inductors are coupled, then the polarity dots should be observed. If not coupled then it does not matter.

Ｂｕｔ　ｈｏｗ　ｄｏ　Ｉ　ｋｎｏｗ　ｉｆ　ｔｈｅｍ　ａｒｅ　ｃｏｕｐｌｅｄ　ｉｎｄｕｃｔｏｒｓ？　Ｃｏｕｌｄ　ｙｏｕ　ｅｘｐｌａｉｎ　ｉｔ　ｍｏｒｅ　ｃｌｅａｒｌｙ？Ｔｈａｎｋ　ｙｏｕ！

 

[CWatters]

An ordinary single inductor isn't polarised, you can fit it either way around. With two coupled inductors (aka transformer) the polarity of one inductor with respect to the other matters. That's why they put a dot. Google transformer dot convention.

 

[lewando]

Here is an example of coupled inductors:
http://www.coilcraft.com/pdfs/msd1260.pdf

The circuit you provided in your OP shows polarization if you choose to use coupled inductors. You do not need to use coupled inductors. Since you have built something already, why don't you tell us what specific components you are using. Also include what diode are you using.

However,the chip always burned out !

Does this mean it never worked? Even at 24 V? Or is there a specific input voltage that makes it fail? What output current are you trying to provide when it fails?