DC-DC step-up converters... how do they work?

[Dan Lenski]

Hi,
I recently heard about DC-DC step-up converters, like this one from Maxim:
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1207

It seems like a cool idea: you can power a 3.3V or 5V device off a single
1.5V cell. I am wondering how they work. I see that all of the ones
that can operate off <1.5V input include inductors. (There are also
capacitor charge pumps that can double a voltage, but none of those can
operate off a single 1.5V cell).

Can anyone give me an explanation of how these inductive charge pumps work?

Thanks,
Dan

 

[PeteS]

Dan Lenski wrote:

Hi,
I recently heard about DC-DC step-up converters, like this one from Maxim:
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1207

It seems like a cool idea: you can power a 3.3V or 5V device off a single
1.5V cell. I am wondering how they work. I see that all of the ones
that can operate off <1.5V input include inductors. (There are also
capacitor charge pumps that can double a voltage, but none of those can
operate off a single 1.5V cell).

Can anyone give me an explanation of how these inductive charge pumps work?

Thanks,
Dan

Read this app note
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1142,C1114,P1134,D4162

(AN73 from linear tech at http://www.linear.com/)

It has a really great description of boost and buck converters.

Cheers

PeteS