Re: [uCsimm] Battery Backup RTC

From: Tom Walsh (tom@cyberiansoftware.com)
Date: Thu Jul 06 2000 - 07:04:06 EDT


SZ wrote:
>
> Unfortunately there is current leak to the peripheral chips such as Flash
> and DRAM. This will drain out the battery in short time. From my
> observation, if I separated the power of DragonBall from main Vcc and off
> the main Vcc with Dragonball on power, it drains about 4mA. This is not
> acceptable for backup battery.

Exactly why I used an external RTC for my design, the DS1306 uses about
1ua of current when on powerdown and with a Lithium cell powering it
(see: 'http://www.openhardware.net/ez328simm/').

Are you absolutely sure that you placed the controller into a DEEP sleep
mode? There is two modes of powerdown, with & without dram refresh. As
for the leakage, that sounds high, did you place the ethernet chip into
SLEEP mode as well? You might be observing the idle current of the
CS8900?

TomW

-- 
Tom Walsh - WN3L - Embedded Systems Consultant
'www.openhardware.net', 'www.cyberiansoftware.com'
"Windows? No thanks, I have work to do..."
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