ICL7660S for bipolar supply.

[fvjake]

Hello all, I'm new to the forum so thanks in advance for any and all help and my apologies for any and all newb mistakes.

I am attempting to create my own clean boost from scratch using a single OPA134 op amp. In doing so have come across a lot of mentions of using an ICL7660 as a voltage doubler for more headroom. I was wondering if anyone uses the same chip to achieve a +/- 9v supply (the chip, besides doubling voltages, can create a negative voltage the same as the input voltage), and if anyone has experienced any pros or cons to using a bipolar supply instead of a single supply in their own pedals.

My thought is that I can do away with the biasing voltage divider circuit and the coupling capacitors found on most designs I have come across. Adding an additional IC to remove a couple resistors and capacitors also seems kinda silly, but I'd like to know any opinions if anyone has any.

Thanks a lot!

[R.G.]

Yes. It's a fairly common practice. See  http://geofex.com/circuits/+9_to_-9.htm for an early version I did back in 2000. I would change out the MAX1044 for another chip if I did that today.

There are several chips that are used to do similar things: ICL7660, ICL7660S, MAX1044, LT1054

The MAX1044 can run at above audio speeds and does not induce whine as the 7660 can if everything is not perfect. The7660S may run at higher speeds - look at the datasheet. The 1054 runs at high speeds. The MAX1044 dies if its input voltage is over 10.000000000V, so it's a bad choice in "9V" powered pedals. The LT1054 is the one I tend to use. The ICL7660S may be fine. Check the datasheet.

[roseblood11]

I always use the ICL7660S as inverter because of the higher input voltage range (up to 12V). It runs at higher speed, I never had any troubles with whine etc. And its MUCH cheaper than the MAX1044/54...
http://uk-electronic.de/onlineshop/product_info.php?products_id=1252&osCsid=d79047e7de07206ec377f4e1be73b85e

[armdnrdy]

I always use the ICL7660S as inverter because of the higher input voltage range (up to 12V). It runs at higher speed, I never had any troubles with whine etc. And its MUCH cheaper than the MAX1044/54...

I use the LT1054CP as my "go to" charge pump. The 1054 is rated for a much higher output current and a higher input voltage than the 7660.

[thelonious]

The ICL7660SCPAZ from Mouser is what I tend to go to. I have occasionally had problems with (supposedly exactly the same, but possibly fake) chips that I've ebay ordered from China because they were cheaper, so let the buyer beware.