43mA current from batteries?

[arrow]

Hi

I am working on a project with an MMC card and my circuit requires 43mA of current at 3.3V.
I have been using a Vregulator: LP2951 3.3V and things are working.

The next step is to get batteries to power the circuit.
We would like to use coin cell batteries say CR2032 3V, or the 12V mini batteries.
However I do not know whether these batteries can provide this amount of current?
Someone told me about a dc-dc converter. But I do not know what these are, and indeed whether I can boost current with these?
Do dc-dc converters replace the Vregulatr?

If someone could guide me, I would greately appreciate it.

Thank you
a.

 

[on1aag]

Hi Arrow,

With this current consumption you should forget about using
batteries, especially the button cells and the little ones. I think
you will be far better off with rechargeable cells. Three cells will
be enough. Take the capacity of one cell, divide it by the current consumption of the circuit and you will get the time that your
rechargeables will be able to power the circuit.

on1aag.

 

[hjames]

For a 6V input and a 3V output, a linear regulator will be <50% efficient, a typical switching regulator will be ~80%, a good one will be >90%. At 12V, the linear will be 25%, while the switching regulator efficiency won't change too much.

www.linear.com has a couple nice small stepdown regulators, as does www.national.com, www.maxim-ic.com, just look for "switching buck regulators"

The large lithium coin cells may be sufficient for a couple hours of operation at 50mA, and I'm not sure what you mean by 12V mini batteries.


James

 

[audioguru]

Your 3.3V regulator needs a minimum input of about 3.6V, so you can't use a single 3V lithium cell. The 8 cells inside a car remote's mini 12V battery are so small that they might not be able to supply 43mA for even only 1 second.

What draws such a high current in your circuit? Hard drive?? Fan motor?? Lights?? Heater for it to keep warm in winter??

 

[TKS]

Maybe a 3.3 regulator is not rentable for your ap because of the low powerconsumption.. search on the TI site and sample some regs that are there for battery powered aps..

for example the REG1117 you can take a 3.3vols version or a adjustable one..
max 800ma max

i copy:
APPLICATIONS

SCSI-2 ACTIVE TERMINATION

HAND-HELD DATA COLLECTION DEVICES

HIGH EFFICIENCY LINEAR REGULATORS

BATTERY-POWERED INSTRUMENTATION

BATTERY MANAGEMENT CIRCUITS FOR
NOTEBOOK AND PALMTOP PCs

CORE VOLTAGE SUPPLY: FPGA, PLD, DSP,
CPU


this is your number: REG1117F-3.3

downside is 4,8volts minimum input.. but it last for ages on batteries

Tks

 

[RODALCO]

Mini 12 volt batteries

These are used in remotes for garage doors.

They look like a 2/3 size AA battery and put out 12 volts. obviously they have 8 x 1.5 volt cells in series.

Forget using one of those, they have not got the capacity