BeagleBoard current consumption

Hi

Before I start looking at the TRM does anyone know if the BBxm power consumption
can be reduced significantly I have a BBxm here that is running the desktop
and its takes around 660-700mA, I have tried reducing the CPU speed from 800MHz
to 300MHz but its makes little difference (less that 100mA). Connected to
the BB I have a keyboard, mouse , USB stick , I have unplugged these and the current
taken by these devices is quite low.

I am looking to battery backup the BB so any reduction in current will increase its
battery life if the mains fails.

I have one power supply that powers the monitor, charges a lead acid battery, this
power supply has to be 12 Volts for the monitor, so I am dropping 7 Volts to supply
A regulated 5v to the BB, I am finalising the hardware at the moment so it might need a
more powerful 5v regulator to handle the heat generated if the BB current cannot be
reduced in anyway.

This maybe an option for using a Raspberry PI in the future as I think it has lower
power requirements?.

TIA

Terry

Are you using a linear regulator? (Your comment about handling the heat generated suggests so.) If so, swapping to a switched mode one will immediately double the run time you can get from any given battery charge.

Hi Dave

I realise that I could use a switching regulator but my main interest
is reducing the current of the BB if possible to increase the battery
backup time, at the moment I am using a 7 Amp lead acid backup battery
to give the backup time I require, I am trying to get RISC OS into the
commercial world but as aways cost is an issue so reducing power requirements
is aways of interest.

Also the system is radio based so linear regulators give much better noise
reduction when dealing with radio power supplies, we can only transmit very
low powers 1mW to 10mW so making the receiver as sensitive as possible
is always a good idea.

I have added an extra heatsink area to the PCB and now the regulator is running
at 70C which is well within its operating range.

Cheer’s

Terry

Radio is what originally hooked me on electronics, at the age of 10, well over 50 years ago now :-)

As with any other electronic circuit, the practical design – including the “stray” components introduced by the PCB layout – can have a major influence on EMC. I can see no reason why a switching regulator should generate any more noise than the BB itself. If it is a problem, filtering and screening are easy in principle to add. Remember, you win by a factor of 2 in power consumption, and therefore battery life, in your case.

I used to worry about noise generated by switching power supplies years ago. Having taken numerous pieces of equipment through EMC tests in the last 20 years, I am far less worried about it.