Real Time Clock

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I am looking for a RTC Chip, maybe with SPI for communications with
68HC908GP32. Any suggestions?

TIA,
David



Re: Real Time Clock
I found the thread dated April 1st 2004, in a Google Groups search for SPI
RTC.

Thanks,
David

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Re: Real Time Clock
Hi,
Be careful if you choose DS1305 !!!
I'm waiting for 100 pcs since 1.5 months...

--

Yvan
http://www.ybdesign.fr




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Re: Real Time Clock
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Depending on your battery current budget, MCUs may not be a good fit.
They normally use a lot more power than a standard RTC which is designed
to run from a watch battery for years, just like watches.  

One exception is the MARC4 (4 bitter) from Atmel and a line of 4 bit
MCUs from EM owned by Swatch (surpise!).  These are both designed to run
from a watch battery at just 1 or 2 uA currents.

--

Rick "rickman" Collins

snipped-for-privacy@XYarius.com
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Re: Real Time Clock
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What about the MSP430? I have one in an application that runs a 32KHz
watch xtal and wakes each second to count time, using an average current
of 0.7uA. The advantage of the MCU is that you can make it do things
when it wakes other than just increment the time.  My app wakes on NVRAM
IButton contact and records its time (32bit seconds or YYYYMMDDHHMMSS)
into the button - reliably! (CRCs, scratchpad readback, all the good
stuff).

Clifford Heath.

Re: Real Time Clock

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You could try Maxim's MAX6902. It is an SPI compatible RTC, with timekeeping
current
consumption of 400nA at 2V. It also operates from 2v -> 5.5V. However it comes
in a
TDFN form factor (3mm x 3mm x 0.8mm).

Accidently flick it with the tweezers and it's gone.

However I understand that Maxim's delivery schedules leave something to be
desired.
Sample deliveries are ok though. Today I received a MAX1811 Li+ charger ic about
a
week after I requested a sample.


Re: Real Time Clock
Hi David,

Some folks have suggested a uC with realtime clock. Here is a good one:
MSP430. Has an internal clock and when shut down with only this RTC
running it consumes just a few micro amps.

Regards, Joerg

http://www.analogconsultants.com

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