MAX1044 charge pump - 10.5V!?

[zpyder]

Reading the data sheet for the MAX1044 charge pumping chip at http://www.ortodoxism.ro/datasheets/maxim/ICL7660-MAX1044.pdf, I see under ABSOLUTE MAXIMUM RATINGS that supply voltage is listed as max of 10.5V

I guess I'm just surprised as this is so close to 9v that I'd be worried about using this in a 9vdc-supplied circuit.  A Battery shouldn't give more than 10.5, but a lot of wall warts out there sure do...

Any ideas!?

zpyder

[boogietube]

I use a boss regulated supply (the red one) and have no problems. They're not expensive.

[Processaurus]

They were meant for 5v circuits originally, running them on 9 is cutting it close.  I made a thing for a friend that had one in it that died after a while (hard to say what killed it), but I stuck a new one in and put a series low value resistor and a beefy 10v Zener diode on its input, to try and keep it from getting fried again.

Also note it's only rated to put out about 10mA.  So if its doing the negative supply in a pedal the total current has to be less than 20mA to be safe.

Is there a beefier charge pump that works above audio frequencies like the MAX1044 available?

[Cliff Schecht]

They were meant for 5v circuits originally, running them on 9 is cutting it close.  I made a thing for a friend that had one in it that died after a while (hard to say what killed it), but I stuck a new one in and put a series low value resistor and a beefy 10v Zener diode on its input, to try and keep it from getting fried again.

Also note it's only rated to put out about 10mA.  So if its doing the negative supply in a pedal the total current has to be less than 20mA to be safe.

Is there a beefier charge pump that works above audio frequencies like the MAX1044 available?

I'll ask my dad, he's an electrical engineer that specializes in power, so he's the man to ask.

I just recently finished up my flanger, I was going to try to run it off of my 9v supply that I built but I couldn't find an effecient way to get the thing to 12v and frankly, using a charge pump to get to 18v and running that through a 12v regulator seemed excessive and redundant, so I'm just using a wall wart for now. Again, I'll get back to you on this, I'm really curious myself.

[Paul Perry (Frostwave)]

LT1054 good to 15V, I think.

[boogietube]

Here's some specs on the LT1054:

  Switching Frequency(Max)(kHz)   35 
Iq(Typ)(mA)   2.5 
Vin(Min)(V)   3.5 
Vin(Max)(V)   15 
Iout(Max)(A)   0.1 
Pin/Package   16SOIC,8PDIP 
Vout(Min)(V)   -5 
Vout(Max)(V)   -5 
Preset Vout(V)   -5 
Priority   3 
Approx. 1KU Price (US$)   1.44   
Operating Temp Range(Celsius)   -40 to 85,0 to 70

Here's a pcb layout that is included in the Clone theory PDF file:

http://topopiccione.atspace.com/PJ12EHCloneTheory.html

[Processaurus]

Vout(Min)(V)   -5 
Vout(Max)(V)   -5 

Are you sure about that? it looked in the app note like when its used as a voltage inverter it could invert whatever voltage was going in.  The bit about having an adjustable regulator is intreguing.  It looks cheaper than the Maxim chip too.

Its weird, I'd been looking at the Line 6 modeller pedals power supply recently and it cuts 9 v down to 6v with a zener diode, regulates that to 3.3v, charge pumps that back up to 6v, regulates it to 5v, and charge pumps it to invert it to -5v.  I want what they were smoking when they decided on that scheme, even if it was probably mountain dew and fritos.

[Cliff Schecht]

Vout(Min)(V)   -5 
Vout(Max)(V)   -5 

Are you sure about that? it looked in the app note like when its used as a voltage inverter it could invert whatever voltage was going in.  The bit about having an adjustable regulator is intreguing.  It looks cheaper than the Maxim chip too.

Its weird, I'd been looking at the Line 6 modeller pedals power supply recently and it cuts 9 v down to 6v with a zener diode, regulates that to 3.3v, charge pumps that back up to 6v, regulates it to 5v, and charge pumps it to invert it to -5v.  I want what they were smoking when they decided on that scheme, even if it was probably mountain dew and fritos.

Wow, that's weird as shit and quite redundant. Like I was saying, I was facing a similar problem trying to power a 12v circuit off of a 9 volt source. I didn't want to use a charge pump into a regulator, but it looks thats my only option right now.

[Paul Perry (Frostwave)]

There's usually a reason for stuff. That 3.3 is doubtless for some damned modern analog or DAC chip designed to run at 3.3 (a suprising amount are).
And there are some high efficiency 3.3 to 5 converters, so might as well use that.
As for the 9 to 6 with a zener followed by the 3.3 reg, a problem might be that the Line 6 is very power hungry and if you ran the reg from 9 (or whatever overvoltage) to 3.3, you would exceed dissapation of the reg.
In fact, if the 3.3 is digital, it makes some sense.......the following reg isolates the analog & digital sections.
Power supply for hybrid (digital/analog) can be quite a hassle, believe me

[boogietube]

Are you sure about that?

That's a cut and paste from the manufacturers website, so, yes I'm sure.