Re: [uCsimm] Battery Backup RTC

From: SZ (
Date: Thu Jul 06 2000 - 04:03:33 EDT

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.


----- Original Message -----
From: David Williams <>
To: <>
Sent: Thursday, July 06, 2000 12:29 PM
Subject: Re: [uCsimm] Battery Backup RTC

> The Dragonball RTC uses the same power source as the CPU. Therefore you
> must ensure that VCC is powered at all times to ensure that RTC keeps
> working. To acheive low power operation you put the CPU into low power
> mode and RTC continues to run. To use a Lithium Cell or other such
> backup power it must be connected to VCC somehow (ie in parallel with
> main supply - obviously being careful not to charge or drain the Lithium
> Cell while running from the external power source.)
> Dave.
> SZ wrote:
> Does the uCSimm H/W does consider to make use of the Dragonball RTC ?
> Can it be backup by say, Li Cell such as CR2032? With
> the system shutdown and the RTC clicking?
> We've try to look into but seems it can't be. Does anyone ever tried to
> implement it?
> Regards
> CC
> This message resent by the list server

This message resent by the list server

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