Minimizing sleep consumption

I'm looking to minimize sleep (off-mode) power usage on my
Beagleboard. From the software side of things, I'm working to get
regulators turned off and or set to sleep mode during sleep. But on
the board, there are a few things that consume quite a bit of power
even during sleep.

The Y1 oscillator (EP16E7E2H-26.000M_TR) uses 9mA@1.8V (16.2mW). It
has a power down mode, but the pin isn't connected to anything, and
anyway, it only gets it down to 4mA. It'd be ideal to connect the
power down pin to the CLK_EN of the TWL4030, but that pin isn't
brought out. So I'd like to connect it to another controllable pin.
I'd also like to replace the oscillator with something that has a
lower sleep mode power consumption. There is a variant of the EP16
that has a power down mode that only draws 30 microamps in power down
mode (EP16E7E2J), but I can't find it available anywhere. The Y1A part
(SG-210SEB 26.0000MF) has much lower power consumption and a low sleep
consumption. Does anyone know of a source where I can get small
quantities of either part?

Other things that consume power that I'm just rambling about...

The TFP410 uses up to 0.5mA@3.3V (1.6mW) during power down mode and
the RS232 transceivers use up to 1mA@3.3V (3.3mW). The transceivers
don't have the FORCEOFF pin tied to a controllable input. I'd like to
hook up the LDO_EN pin of the 3.3V regulator to a GPIO so that I can
power if off during sleep.

The power LED uses 10.6mA@4.2V (44.52mW). I'd like to move that over
to the 3.3V rail so that it turns off with the 3.3V rail.

I have no plans to make any changes to the board as you have suggested. We are into the next pahse of production and boards are already in the pipeline. I will take your suggestion under consideration on future spins of the board.

Feel free to modify the board as you choose with the understanding that it will violate the warranty and we will not be able to repair. If you like, you can make these changes and spin your own version of the board.

Gerald

I have no plans to make any changes to the board as you have suggested. We
are into the next pahse of production and boards are already in the
pipeline. I will take your suggestion under consideration on future spins of
the board.

Feel free to modify the board as you choose with the understanding that it
will violate the warranty and we will not be able to repair. If you like,
you can make these changes and spin your own version of the board.

Yes, I understand, my main goal of the email is to try to obtain some
lower power oscillators. When I complete my research, I'll post the
results including any hardware modifications and their effects on
power consumption.

The best solution is to use a crystal. When the board was designed, there was an issue in the OMAP3 that prevented it from working correctly, a ROM issue, so we had to use the external oscillator. That has sense been fixed. The PMIC also needs the 26MHz, so any solution should take that into cnsideration as well.

Gerald

You might make a project out of a lower-power Beagle and register it in the contest entries.