1044scpa vs 7662CP vs 7660

[jessenator]

Ah, I've been meaning to ask the board about TC7660H, no downsides beside the max input voltage?

I'll admit, I haven't done anything especially engineering-y beyond testing in circuits requiring split rail. Eliminating the whine by putting the freq well out of the audible range was my only concern.

 

[BrooksBlackhawk]

Why?

Oh just because I’m dealing with a build that is “whining” and this was one of the more helpful threads on charge pumps here. I noticed the 7662 was mentioned but only briefly and wanted to contribute.

LTC3863
Higher current output and high voltage input and up to 350kHz
If you want to max spec it...

I hadn’t heard of this one, I’m checking it out now, thanks for the suggestion!

 

[BrooksBlackhawk]

While I hope it works out for you, what we sacrifice for maximum voltage is oscillator frequency. Personally, I find the latter more appealing.

From the TC7662 datasheet:


I mean, if VFE circuits aren't having squeal/heterodyne problems, that's something, but butter safe. I've just defaulted personally to the TC7660H, which has a frequency of 120kHz, but a max input voltage of 10V. Lower than the TC7660SCPA's 12V, but no pin bridging required, and nearly 3x the max frequency.

I totally agree with the frequency being the most important factor with a 9+/9- CP.
For preamp designs, when it comes to higher voltage split rails without whine I’ve defaulted to the big DC>DC converters in SIP packages like the TRACO, MEANWELL RECOM ones.

However for just wanting some headroom and to design in the dual rail bi-polar way for basic pedals, knowing about better CP chips is great! I will absolutely look at the 7660H!

 

[szukalski]

The more pressing concern is price. What’s the cheapest option?

 

[micmac]

h just because I’m dealing with a build that is “whining” and this was one of the more helpful threads on charge pumps here. I noticed the 7662 was mentioned but only briefly and wanted to contribute.

Hello, if you got charge pump whine I suggest to put some 470nF MLCC caps at the input and the output(s) of the charge pump to ground. Works every time for me. Have a look at the aion Straylight and Ember. That's where I first saw people doing it.

 

[micmac]

Here's a link from a few years ago where somebody looked into the charge pump noise and tried a lot of stuff and the extra filter caps killed the high frequency ripple: Link