max1044 charge pump layout, can you guys look it over?

[Barcode80]

i'm not sure about the electro orientation, so i was wondering if you guys could help me with extra eyes to look this over...

it is from the article on geofex.com describing how to pump 17 volts from a 9 volt supply

[soulsonic]

You need to have a 10uF cap between pins 2 and 4 or it wont work.

[DiamondDog]

You could try this for a reference source.

Cheers,

DD

[Auke Haarsma]

Looks correct to me Barcode.

You need to have a 10uF cap between pins 2 and 4 or it wont work.

From the Geofex site:

The MAX1044 is a charge pump converter - it uses a capacitor as a "bucket" to pump charge from one place to another. Normally, there is a capacitor connected from pin 2 of the 1044 to pin 4. This capacitor is charged between +9V and ground, and then switched in parallel with a capacitor from pin 5 to ground in a way that makes a negative voltage on the second cap.

In this UPverting use, the 1044 still switches pin 2 between +9V and ground just as it would for a voltage inverter. However, we ignore the pin 4 and 5 connections that would make an inverter from it. Instead, we connect two capacitors and diodes as shown (D1, 2, and C1, 2). The voltage on pin 2 of the 1044 is switched from +9V to ground. When it switches to ground, C1 fills with voltage through D1. When it then switches to +9, it pulls the negative terminal of C1 up to +9V. D1 now blocks any flow of current back into the battery, so the charge in C1 flows through D2 into C2. So at C2, we now get almost 18V!

I understand this as that there's no cap needed between pin 2 and 4.

[Auke Haarsma]

You could try this for a reference source.

Cheers,

DD

+1

[Paul Perry (Frostwave)]

http://www.maxim-ic.com/appnotes.cfm/appnote_number/725
another good reference 

[soulsonic]

Okay, I see - C1 is performing that chore. Nevermind then, it's fine.

[grolschie]

n00b question: Could this circuit be used to power a Ruby mini amp at higher voltage off a 9v supply? Providing higher rated components are selected. People mention using higher voltages in the Ruby for more headroom.

[soulsonic]

I don't think it can really push enough current to do a good job with an amp - even a small one like a Ruby.

[Barcode80]

i think it could do the ruby, but you don't want to do it off a battery this way, battery would be dead in 5 minutes