Charge pump tripler ,will it work ?

[Kevin.D]

Please help guys.
While searching for information about using the icl7660  voltage converter to
use as a positive voltage multiplier (using cascaded devices to triple  + input voltage).
I found this interesting little snippet .
http://www.maximintegrated.com/app-notes/index.mvp/id/297
It shows a way to use a single max1683 voltage doubler as a tripler .I am not sure 
 how this works ,my head is fried . 
Anyway do you think  this could be done with a icl7660 using a single device to triple input voltage. .
 The icl7660 is slightly different in the way it works to the max IC by the look of it  .
here's data sheet to  icl7660
http://www.intersil.com/content/dam/Intersil/documents/fn30/fn3072.pdf
here the max1683
http://datasheets.maximintegrated.com/en/ds/MAX1682-MAX1683.pdf

[Bored@Work]

It is an old trick. A cascade driven by a charge pump or smps.

[Marco]

You could, but essentially you're just using the ICL7660 as an oscillator (even with the doubler in the datasheet that's already the case). With the Maxim you're saving one diode drop compared to a full tripler.

I'm surprised there are no general charge pump triplers available ... what you can do though is have two voltage doublers and simply use the doubled voltage as the supply voltage for the second and the original voltage for it's "ground". That way you have a fully synchronous voltage tripler (ie. no diode drops). I wish I could claim I immediately realised that myself ... unfortunately I ain't that smart

Read it here : http://ww1.microchip.com/downloads/en/devicedoc/21516c.pdf

[Kevin.D]

Thank you marco for that reply .
If you look  at the icl7660 data sheet  you will see in the example of
the positive voltage doubling example requires two diodes in the output so you get 2 Vf diode drops , and then  you'd get another two Vf drops if your cascading them again I think .
The maxim chip and the one you linked to don't seem to  need diodes  on their output in order to double voltage .  That's why I asked ,because of this difference in the way the caps and diodes are connected on the icl76660 chip , I don't think
that the trick of using one device to triple voltage will work  . ?

[Marco]

It can work, but you're looking at 4 diode drops with the ICL7660 ... hardly ideal.

[codeboy2k]

also as you start cascading icl7660's the final impedance goes up, so you need to be sure that you don't end up with such a high output impedance that you can't drive the load anymore.

Just something to watch out for with charge-pumped voltage doublers and triplers, and cascades of these.