Re: [uCsimm] Battery Backup RTC

From: SZ (
Date: Thu Jul 06 2000 - 22:07:59 EDT

Actually I have cut out the power supply path of the DragonBall isolated
from the peripherals. Regarding peripherals, I have switched off the Vcc. I
have set the register of DragonBall to Sleep : PCTRL to 0x80h and the
current for the Dragonball can be instantly turn to uA. But when I cut the
peripheral power, it jump back to 4mA.


----- Original Message -----
From: Tom Walsh <>
To: <>
Sent: Thursday, July 06, 2000 7:04 PM
Subject: Re: [uCsimm] Battery Backup RTC

> SZ wrote:
> >
> > Unfortunately there is current leak to the peripheral chips such as
> > 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
> > 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: '').
> 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
> '', ''
> "Windows? No thanks, I have work to do..."
> This message resent by the list server

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