Egodriver Charge Pump

[teknoman2]

I just design egodriver using max1044 for voltage doubler but I am not sure
about the 18v supply section,

https://www.dropbox.com/s/e5q87ibmp8tc8gu/egodriver.png


I design my power supply using reference the max's datasheet.
I checked on other projects and I realize that many connect pin 1 with pin 8.
My main issue is do I have to change anything in my schematic on the power supply section?

[jkokura]

Couple small thoughts.

1. Don't use the MAX chip. It sucks. It's prone to blowing, and it's expensive. A very good alternative is to use a TC1044 chip. It's essentially the same, can run on a higher voltage (handy for keeping it from blowing), and is cheaper to boot (significantly).

2. Yes, you need to connect pin 1 and 8 using both the TC1044 and the MAX1044.

3. It's typical to use a value of 10uF for C12 and C13. While I think 1uF will do the job, consider using a 10uF/22uF/47uF value.

Jacob

[teknoman2]

Thanx jkokura for such a quick feedback,
do you know why we have to connect pin1 and 8?
I am asking cause on the datasheet of max1044
doesn't connect pin1 and 8.

http://www.taydaelectronics.com/datasheets/A-846.pdf

[jkokura]

Check out page 7, the upper right, of that datasheet.

Jacob

[teknoman2]

Thanks for your advices Jakob,
you were as always very helpful.
Last question do you recommend of using charge pump on the egodriver?
Some say it gives more headroom, is that true?

[jkokura]

Thanks for your advices Jakob,
you were as always very helpful.
Last question do you recommend of using charge pump on the egodriver?
Some say it gives more headroom, is that true?

I don't usually buy into the 18V makes an overdrive better philosophy. Most of the time, I can't tell the difference in casual playing tests. However, the Egodriver/OCD circuit was the first one where it was noticeably better using 18V for me. I don't know why, but it was really obvious. I think it's a great idea to put it on a switch like you're done - you'll really be able to tell.

Jacob

[GrindCustoms]

I would recommend using a 9.1V zener to protect your opamp IC and charge pump IC if you use a ICL7660S wich is also a great alternative to the MAX1044 but has a maximum input voltage of 9V

Maximum voltage rating of the opamp is 18V, if by any means you have more than 9V from your power supply, you'll be exceeding the IC voltage rating...on the long term run you'll fry it.

[Scruffie]

I would recommend using a 9.1V zener to protect your opamp IC and charge pump IC if you use a ICL7660S wich is also a great alternative to the MAX1044 but has a maximum input voltage of 9V

Maximum voltage rating of the opamp is 18V, if by any means you have more than 9V from your power supply, you'll be exceeding the IC voltage rating...on the long term run you'll fry it.

The OpAmp rating is 36V, it's +/-18V so in total, 36.

A series polarity protection diode with the power supply is probably sufficient to protect the MAX chips 10V max input, as long as you don't use a 12V supply and the 0.6V drop of a 1N400X Diode will hardly be a big deal with a doubled voltage.

[GrindCustoms]

I would recommend using a 9.1V zener to protect your opamp IC and charge pump IC if you use a ICL7660S wich is also a great alternative to the MAX1044 but has a maximum input voltage of 9V

Maximum voltage rating of the opamp is 18V, if by any means you have more than 9V from your power supply, you'll be exceeding the IC voltage rating...on the long term run you'll fry it.

The OpAmp rating is 36V, it's +/-18V so in total, 36.

A series polarity protection diode with the power supply is probably sufficient to protect the MAX chips 10V max input, as long as you don't use a 12V supply and the 0.6V drop of a 1N400X Diode will hardly be a big deal with a doubled voltage.

That is if he uses a Bi-Polar charge pump configuration, wich is not the case here...so it's 18V+ max....

Anyway....maybe i just over protect my circuits....

[culturejam]

Man op amps have a voltage differential of 30v (+/- 15v), while some have 36v (+/- 18v).

But either way, you can't hit either power rail with the full differential rating voltage.

[GrindCustoms]

Here's my charge pump configuration for 18V+.....

[Scruffie]

I would recommend using a 9.1V zener to protect your opamp IC and charge pump IC if you use a ICL7660S wich is also a great alternative to the MAX1044 but has a maximum input voltage of 9V

Maximum voltage rating of the opamp is 18V, if by any means you have more than 9V from your power supply, you'll be exceeding the IC voltage rating...on the long term run you'll fry it.

The OpAmp rating is 36V, it's +/-18V so in total, 36.

A series polarity protection diode with the power supply is probably sufficient to protect the MAX chips 10V max input, as long as you don't use a 12V supply and the 0.6V drop of a 1N400X Diode will hardly be a big deal with a doubled voltage.

That is if he uses a Bi-Polar charge pump configuration, wich is not the case here...so it's 18V+ max....

Anyway....maybe i just over protect my circuits....

Yes but we use a V.ref, the IC thinks 9V is 0V as far as it's concerned, Gnd is its -9V.

Zeners as shunt regulators aren't great and can fail unless the supply is current limited. Just think a series resistor and a diode in series should be in there anyway and should be enough.