Some charge pump questions and considerations

[midwayfair]

I'm making a handful of layouts for circuits that run "best" on 18v. So I'm making myself a generic little charge pump so I don't have to redraw the same thing several times.

My first instinct is to use a 1044SCPA, but is there a better overall choice all other things being equal?

[jkokura]

There isn't a less expensive option than the TC1044scpa from Mouser. Get 10 of them and they're less than $1 each. I haven't seen anything cheaper that does the same thing.

Jacob

[stecykmi]

the lt1144 is a hardier version of the 1044, it can handle an input of 18V and can sink 50mA. you may consider using that instead.

[RobA]

I did some testing earlier with various charge pumps. There's a thread around here where I reported in a bit of detail what I found. But, the main upshot was that most of the TC1044SCPA's I tested had significantly lower oscillator frequencies than the specified typical value. Even when using the boost pin, several had audible whine.

On the other hand, the LT1054 parts all worked quite well and had no audible whine and a scope showed them to all be oscillating above 20kHz. I'm only using the LT1054's at this point.

Mouser's price on the LT1054 is pretty high, but Avnet has a much better price.
http://avnetexpress.avnet.com

Rob

[midwayfair]

I did some testing earlier with various charge pumps. There's a thread around here where I reported in a bit of detail what I found. But, the main upshot was that most of the TC1044SCPA's I tested had significantly lower oscillator frequencies than the specified typical value. Even when using the boost pin, several had audible whine.

On the other hand, the LT1054 parts all worked quite well and had no audible whine and a scope showed them to all be oscillating above 20kHz. I'm only using the LT1054's at this point.

Mouser's price on the LT1054 is pretty high, but Avnet has a much better price.
http://avnetexpress.avnet.com

Rob

I remember that thread. I soldered up the first of these; I'll see what happens with the TC charge pump. I only had one LT around and it's currently living in my permanent charge pump test unit. If there's a whine in the TC I used, it's not too hard to desolder pin 1 of the socket and change out the charge pump.

Thanks for the lead on the source. I do like the LT in general because it saves me having to make space for a 9.1v Zener, but the Mouser price was a bit of a turn off.