Battery Voltage Boost

[S. Ethier]

I have a circuit that requires 3.3V DC (typically) to operate. It also
has a minimum required voltage of 2.97V DC.
Because of design size restrictions, I was hoping to use 2 AAA batteries
to power the circuit. This would give me a maximum voltage of 3.0V DC
(ideally conditions).
Is there anything out there capable of generating a higher output
voltage than the input source, so that even if the voltage drops below
2.9V my output voltage for my circuit remains constant at 3.3V?

Steph

 

[Chris W]

S. Ethier wrote:

I have a circuit that requires 3.3V DC (typically) to operate. It also
has a minimum required voltage of 2.97V DC.
Because of design size restrictions, I was hoping to use 2 AAA
batteries to power the circuit. This would give me a maximum voltage
of 3.0V DC (ideally conditions).
Is there anything out there capable of generating a higher output
voltage than the input source, so that even if the voltage drops below
2.9V my output voltage for my circuit remains constant at 3.3V?

Steph

How about a
http://rocky.digikey.com/WebLib/Linear%20Tech/Web%20Data/LT1300.pdf
I found the data sheet at digikey, their pn is LT1300CN8. search the
site for step up, and you will find lots of chips.

--
Chris W

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[Mac]

On Sat, 16 Apr 2005 23:21:30 -0400, S. Ethier wrote:

I have a circuit that requires 3.3V DC (typically) to operate. It also
has a minimum required voltage of 2.97V DC.
Because of design size restrictions, I was hoping to use 2 AAA batteries
to power the circuit. This would give me a maximum voltage of 3.0V DC
(ideally conditions).
Is there anything out there capable of generating a higher output
voltage than the input source, so that even if the voltage drops below
2.9V my output voltage for my circuit remains constant at 3.3V?

Steph

If you are going to use a boost regulator anyway, consider starting with
one AA cell. It appears to me that there is more energy available in a
AA cell than there is in two AAA cells.

See the relevant datasheets at:
http://www.duracell.com/oem/productdata/default.asp

In particular, the Amp-hour rating of the AAA cell when discharged at
250 mW is around 0.78 Amp-hours. This uses 0.8 V as the cutoff threshold.

For the AA cell under the same conditions, the Amp-hour rating is around
2.2 Amp-hours.

By the way, how much current do you need at 3.3 V? If you need very low
current for a very long time, I don't think typical boost regulation
schemes will be feasible, but I'm not an expert.

--Mac