+/-15V with MAX1044

[R.G.]

Don't let anyone tell you MAX1044's won't run on 12 volts - they do.

OK.

Here's what the guys who make that chip say. From http://datasheets.maxim-ic.com/en/ds/ICL7660-MAX1044.pdf

ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V+ to GND, or GND to VOUT)....................10.5V

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

I don't think they could be any clearer at saying "Although one or more of these devices might work at higher voltages, we will not guarantee them to work over 10.500V. If you use them over that and they fail, don't say we didn't tell you so and don't come crying to us for replacements."

So you may well have one or more running on 12V. Whether the next one runs on 12V or not, or the one you buy in two months will is pure conjecture. Or it may fail as soon as it gets hot. Or after running for six months.

Although most devices do work a bit over their maximum rating, it is silly to expect them all to. In my last job, we would have reprimanded and given remedial instruction to a junior engineer for doing that, and fired a staff engineer or above for it. For you to do it, you only have to answer to yourself, so best of luck.

[Dimitree]

btw..I'd use it with a common 9v adapter, such as 1spot or godlike power all..

[ClinchFX]

It puzzles me that so many folks still use the MAX1044 when the LT1054 has an input voltage spec of 3.5V to 15V, higher output current capability and a native switching frequency of 25KHz for higher efficiency.

If you look at the LT1054 data sheet from TI,http://focus.ti.com/lit/ds/symlink/lt1054.pdf there are some included application schematics, including one that produces doubled +/- outputs with one chip.

Peter.

[R.G.]

Yep. The LT1054 is what I use in later designs.

[The Tone God]

I too have used LT1054s. Nice for what they are. I'm still kind of surprised people haven't caught on to them.

Andrew

[frequencycentral]

I don't think they could be any clearer at saying "Although one or more of these devices might work at higher voltages, we will not guarantee them to work over 10.500V. If you use them over that and they fail, don't say we didn't tell you so and don't come crying to us for replacements."

So you may well have one or more running on 12V. Whether the next one runs on 12V or not, or the one you buy in two months will is pure conjecture. Or it may fail as soon as it gets hot. Or after running for six months.

Although most devices do work a bit over their maximum rating, it is silly to expect them all to. In my last job, we would have reprimanded and given remedial instruction to a junior engineer for doing that, and fired a staff engineer or above for it. For you to do it, you only have to answer to yourself, so best of luck.

Ouch! Ok, busted! I'll clear my desk and be gone by lunchtime.

Thanks ClinchFX, I'll definately be getting some  LT1054 - the datasheet says they're pin for pin compatible with MAX1044.

Things have a way of working themselves out for the best. I'm using MAX1044 from the Geofex tip - thank you R.G. I'm powering at 12 volts because I had no other options at the time - the circuit I'm working on has tubes and I need 12 volts for the heaters, and I need to give the plates considerably more than 12 volts to get symmetry from a cathodyne phase inverter stage. If I hadn't mentioned that I'm doing it the wrong way (MAX1044 @ 12 volts) I wouldn't have found out about the right way (LT1054 @ 12 volts). I love this forum.

[Dimitree]

seems like I can't use these ICs..    I need about 150mA..and the LT1054 give 100mA

[R.G.]

You can put them in parallel for more current.

[Dimitree]

good! so you think I can get +/-15V from 2 LT1054 using a 9VDC adapter?

[zeeman]

This is working on my breadboard right now. I've had it running for many hours over a few days.

With a load and in use? If not, try powering up a pedal with it and play for a while and lets see what happens.

zeeman

[ClinchFX]

the datasheet says they're pin for pin compatible with MAX1044.

The data sheet says they are pin for pin compatible with LTC1044/7660, but be aware that pin 1 has a completely different function from a MAX1044.  Grounding pin 1 on a LT1054 will shut it down.  Pin 6 also has a different function from MAX1044.

seems like I can't use these ICs..    I need about 150mA..and the LT1054 give 100mA

Do you mean a total of 150mA from both, or 150mA for each of the + and - supplies?  If it's 150mA from each, that's a total of 300mA and even two LT1054s in parallel won't do it.  You'd need three, and even then you'd be right on the limit.  The MAX1044 would be completely out of the race either way.

Peter.

[soulsonic]

You can get a bipolar voltage-doubled supply from a MAX1044; you just have to use two of them.
Here is design I did for it. This has been tested on breadboard and it works fine.
http://www.aronnelson.com/gallery/main.php/v/soulsonic/Double+Chip+Doubler+copy.gif.html

[Processaurus]

Yeah, I've read the notes. all I can say is that I know from experience that they work at 12 volts over extended periods.

My experience has been the dismal opposite  .  Also they have mediocre current sourcing abilities (10mA). There are more robust charge pump IC's out there, for sure.

However, a lot of projects would run fine on +/- 9v.  That's tons of headroom, an 18v peak to peak signal is HUGE.

[Dimitree]

No I need 150mA for the entire pedal..but maybe 100mA are more than enough.. I'll try.. Now I try to draw a circuit 9vDC to +/-15V with the LT1054 and post it here to let you check it.. 

[frequencycentral]

This is working on my breadboard right now. I've had it running for many hours over a few days.

With a load and in use? If not, try powering up a pedal with it and play for a while and lets see what happens.

zeeman

At the risk of getting shot down (again), I'm powering the plates of two 6111 submini tubes, and a couple of transistors. I'm playing through it. No blue smoke or flames yet! I'm taking advice and ordered some LT1054 though.

the datasheet says they're pin for pin compatible with MAX1044.

The data sheet says they are pin for pin compatible with LTC1044/7660, but be aware that pin 1 has a completely different function from a MAX1044.  Grounding pin 1 on a LT1054 will shut it down.  Pin 6 also has a different function from MAX1044.

Thanks again for the tips Peter.

[Dimitree]

it seems that the frequency of this LT1054, which is 25KHz and a max of 35KHz, will cause whine in audio.. How can I repair that?

[Paul Perry (Frostwave)]

A 'brute force' way to get any hum & noise out, would be to use voltage regulators (if there is enough headroom to run the regulators).
There would certainly be enough output voltage to run + and - 12V regulators, maybe enough for + and - 15V regs.

[ClinchFX]

it seems that the frequency of this LT1054, which is 25KHz and a max of 35KHz, will cause whine in audio.. How can I repair that?

Man, if you can hear 25KHz, you musn't be human.  25KHz is beyond the range of human hearing.  It's possible to get a beat frequency, the difference between your signal frequency and 25KHz ripple on the power supply, but 25KHz ripple is very easy to filter out with just a capacitor.  There's really no need for elaborate sub-regulation.  The other point is that the response of most guitar amps and pedals doesn't go much higher than 8 or 9KHz.

Those of us who have been using the LT1054 haven't experienced any whine problems.

Peter.

[Dimitree]

Good.. Thanks Peter!

[flo]

The ICL76606S is also interesting, for supply voltage up to 13V, and is pin2pin compatible with MAX1044 including the frequency boost:
http://www.datasheetcatalog.org/datasheet/intersil/fn3179.pdf
Make sure to use the *S type!