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Re: DP Ram Emulator...
Eric Aos wrote:
>
> What about the battery? Would 2 3v coin cells be apropriate? (210mAh
> each, with a 5mW consumption by the DPRam = quite a bit of backup???).
> If so, how do I regulate it to 5v ? 7805? or ???
The Cypress DPRAMs want a standby voltage as low as 2 volts. The IDT
data sheet for the 64K DPRAM doesn't mention standby at anything other
than 5 volts - however, the data sheet for a smaller IDT DPRAM mentions
the same 2 volts. Try just one of those 3 volt cells.
To get the reduced power consumption of standby mode, all inputs to the
DPRAM must be at essentially GND or whatever the VCC voltage is. This
generally means that you need to have pulldown resistors on all bus
lines. (You could use pullups to the battery voltage, but then you'd
have leakage into a powered down ECM.)
--
Ludis Langens ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies: http://www.cruzers.com/~ludis/
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