Fran,
What do mean by "Letting the current settle will help a lot getting to
the 2uA state in these ram chips." ?
I am not following what you're saying.
Mike.
--- In korgpolyex@yahoogroups.com, "narfman96" <narfman96@...> wrote:
>
> Mike,
> Button cells are available in larger sizes too. Some of the gear I
> have uses a CR2450 which has 620 mAh of storage. I have a problem
> with some of the rechargeables especially the NiCad nightmares I've
> seen in the Peavey equipment. I replace them with cell phone
> batteries mounted in a remote location away from all boards and
> switches.
> Letting the current settle will help a lot getting to the 2uA state
> in these ram chips.
> Fran
> --- In korgpolyex@yahoogroups.com, "korgpolyex800"
> <korgpolyex800@> wrote:
> >
> > Hi Atom,
> >
> > I will see if I can measure the current but at low current draws the
> > meter may not be entirely accurate. I'll give it a go though.
> >
> > According to the datasheet, if I take CS1 high or CS2 low before the
> > power supply drops from 5V to battery 3V, then the current draw will
> > be 2uA (typical) up to 100uA (max). But the datasheet seems a bit
> non
> > specific about the timing of the chip select lines being at correct
> > levels prior to the supply dropping to 3V.
> >
> > So I have a couple of theories as to why the battery is going flat
> > fast. First, the CS2 chip select line was not being pulled down to
> 0V.
> > I've placed a 10K pull down on that line. I am hoping that this,
> easy
> > to install, extra resistor will fix the problem.
> >
> > Second, perhaps the timing of the shutdown of power from 5V to 3V
> (on
> > battery) is critical. If that is the case, then I can see a
> situation
> > where the chip select lines could be in the wrong state when the
> power
> > down occurs. In that circumstance, the battery will pull alot more
> > current while on battery. As I said though, the datasheet is doesn't
> > explain the timing very well. Nevertheless, if the one pull down
> > resistor doesn't fix the problem then I'll add a capacitor on the 3V
> > battery side of the power supply to the two static RAMs. This will
> > ensure that the chip select lines settle into their correct state
> long
> > before the memory power supply falls from 5 to 3V.
> >
> > So I don't think this is a big problem, it is just going to take a
> > while to work out exactly what has to be done. I am hoping that the
> > single 10K ohm pull down resistor is all that is needed.
> >
> > Zoinky makes a good point though. The button cell most certainly can
> > be replaced by two AA batteries. I like the button cell because it's
> > guaranteed not to leak all over the insides of your precious
> synth's.
> >
> > I cringe thinking about the number of Poly's that have been sitting
> in
> > storage with batteries slowly decomposing all of the PCB's. I bought
> > one on ebay specifically because the case, joystick etc was in
> perfect
> > condition while the insides were completely acid wrecked.
> >
> > I think the button cell should be OK in the long run. It is just
> going
> > to take a few months to be certain that it is set up just right.
> And I
> > wanted to warn everyone before they lose their patches.
> >
> > Mike.
> >
> > --- In korgpolyex@yahoogroups.com, Atom Smasher <atom@> wrote:
> > >
> > > On Tue, 27 May 2008, korgpolyex800 wrote:
> > >
> > > > So, I had a look at the design and think I might have missed a
> > pull down
> > > > resistor that would reduce the current by about half. I've
> added the
> > > > pull down onto both of the HAWK-800 kits and I guess in about
> six
> > weeks
> > > > I'll know if it made any difference at all.
> > > =================
> > >
> > > do you have a multi-meter? measure how much current is moving
> > through the
> > > battery...
> > >
> > >
> > > > A single 6264 static RAM in standby mode uses between 2 and
> 50uA.
> > > ==============
> > >
> > > that's a big range... what determines the actual current?
> > >
> > >
> > > > The longer term solution is now being looked at. There are two
> > ways to
> > > > go about this. One way would be to use a rechargeable battery
> > scenario.
> > > > The other, would be to write patches into flash memory. I'll
> post
> > again
> > > > as soon as I come up with a solution.
> > > ================
> > >
> > > a slightly larger rechargeable battery (1/3 AA) would have a
> better
> > > amp-hour rating, and would last longer than a 2032. i've seen
> gear with
> > > original 10-15 year old lithium batteries running strong.
> > >
> > >
> > > --
> > > ...atom
> > >
> > > ________________________
> > > http://atom.smasher.org/
> > > 762A 3B98 A3C3 96C9 C6B7 582A B88D 52E4 D9F5 7808
> > > -------------------------------------------------
> > >
> > > "In peace, sons bury their fathers.
> > > In war, fathers bury their sons."
> > > -- Herodotus
> > >
> >
>