Charge Pump Voltage Low ?

HOTTUBES · February 20, 2014, 07:23:40 PM

I built a charge pump out of some vero board last night , and after it was
all fired up , i checked the output voltage with my DMM , and reads 16.52 volts ...

Is this normal or is this low ? The supply voltage is 9.11 volts ...

I used a Maxx1044CPA

Here's the layout that i fallowed ...

amptramp · February 20, 2014, 07:44:26 PM

You have a diode in series with the input that drops about 0.7 volts, so the 9.11 supply becomes 8.41 at the input to the device. You then have two diode drops at the output. The basic charge pump circuit takes a capacitor and connects it to the input voltage then uses FET switches to connect the capacitor in series with the input with timing set by an internal oscillator. Check Figure 9 of this data sheet for your circuit:

http://www.futurlec.com/Maxim/MAX1044CPAa.shtml

armdnrdy · February 20, 2014, 07:51:41 PM

Ron beat me to it.

The data sheet says to use schottky diodes to reduce the voltage drop.

So with the 4001s in the circuit you posted....you won't be seeing close to 18 volts.

PRR · February 20, 2014, 10:14:59 PM

Also: 1n400x diodes are slow, possibly slower than the pump rate. If the speed shortage is marginal, you might have slightly-low voltage.

HOTTUBES · February 21, 2014, 12:32:40 AM

That could be the culprit

?

Cause i did use standard 1N4001 diodes in all three locations ...

Does anyone know what schottky diodes to use ?

I have some BAT41 diodes here , would those work ??

armdnrdy · February 21, 2014, 12:50:50 AM

BAT41s will work fine.

I keep 1N60P as my "go to" schottky.

italianguy63 · February 21, 2014, 03:36:18 AM

I've been using 1N5817 with good results. MC

tonyharker · February 21, 2014, 05:32:22 AM

Are 1N60s Schottky diodes or Germanium? Many sellers on eBay disagree and either quote Germanium or Schottky.

Tony

bluebunny · February 21, 2014, 08:28:49 AM

Quote from: tonyharker on February 21, 2014, 05:32:22 AM
Are 1N60s Schottky diodes or Germanium? Many sellers on eBay disagree and either quote Germanium or Schottky.

I could very easily be wrong, but I think 1N60 is Ge and 1N60P is Schottky. And some vendors are none too picky about including the "P" or not. But I could be wrong...

Pojo · February 21, 2014, 12:50:05 PM

Quote from: bluebunny on February 21, 2014, 08:28:49 AM
Quote from: tonyharker on February 21, 2014, 05:32:22 AM
Are 1N60s Schottky diodes or Germanium? Many sellers on eBay disagree and either quote Germanium or Schottky.

I could very easily be wrong, but I think 1N60 is Ge and 1N60P is Schottky. And some vendors are none too picky about including the "P" or not. But I could be wrong...

^This^ has been my understanding as well.

On another note, I have a handful of TL7660's that I *cannot* get functioning as a 9V doubler on breadboard following page 12 of the datasheet. The negative supply generator works fine however.

armdnrdy · February 21, 2014, 12:58:19 PM

This manufacturer is listing both 1N60 and 1N60P as germanium.

http://www.taitroncomponents.com/catalog/Datasheet/1N60.pdf

The 1N60Ps that I have here have a .24 voltage drop. The 1N34As (germanium) I have read in the .4 range.

italianguy63 · February 21, 2014, 03:22:43 PM

Hey Mike-- are those the "S" 7660's? If so, I can trade you out for some MAX1044's if you are OK with those. I have quit using the MAX1044's and have switched to LT1054 and most recently TC1044S from Tayda. MC

Pojo · February 21, 2014, 04:33:32 PM

Not sure, I'll look when I get home tonite! I think I have 2 different suffixes

HOTTUBES · February 22, 2014, 12:37:18 AM

I went with the Maxx1044SCPA as i was told these run quiet . Some builders have reported the CPA to create a " whine " , with that said , i have built several Klon clone OD circuits using the CPA and never had a problem .

italianguy63 · February 22, 2014, 01:53:58 AM

I like the MAX1044. Yes, it is very quiet. There is a report that if you "overvoltage" them >9V, they will fail; and some wall-worts rated at 9V put out greater than 9V, hence causing failures. Mind you, I have never personally experienced a failure myself. But, armed with that knowledge (since you read it on the Internet, it must be true!) I just started buying the LT1054, and then the TC1044S. Both of these too have high operating frequencies and are quiet, and operate at slightly higher rated voltages. Since I found the TC1044S at Tayda extremely inexpensively-- it was a no brainer. I hope this is useful information. MC

Pojo · February 22, 2014, 03:10:19 AM

Mine are suffixed with IP and CP, no S unfortunately. I got them as free samples through TI just to have if needed for a future project...still really strange how I cannot, for the life of me, get the doubler functioning. Appreciate the offer though Mark! If you really do need some of these hit up TI and have them send you samples

italianguy63 · February 22, 2014, 04:44:36 AM

Thanks Mike-- since those don't have the "S" suffix, they will be lower frequency, and you will hear whine unless you filter the heck out of the circuit. MC

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Charge Pump Voltage Low ?