The solution I used for my 2440 which I have discussed here a couple
of times was to use the SRAM and EEPROM based NVRAMs from Cypress
which as far as I have been able to tell in this case, can be used as
direct replacements for the Dallas/Maxim SRAM based NVRAMs. They are
not really any less expensive though than new Dallas/Maxim NVRAMs.
They only save the SRAM contents to the EEPROM when power is removed
or if specifically asked which is not going to happen without a
firmware change so continuous writes are not a problem.
I also considered reverting my 2440 to the earlier design where an
external lithium cell was used.
On Sun, 17 Mar 2013 15:21:13 -0700 (PDT), Gala Dragos
<gala_dragos@...> wrote:
You could add extra logic and a counter to switch between fram chips and increase the mtbf time, or even better make your own NVRAM.
Oh, and if you keep the fram at 25?degrees?Celsius?you will probably get 10 times more write cycles.
--- On Sun, 3/17/13, bravovb <vbingei@...> wrote:
From: bravovb <vbingei@...>
Subject: [TekScopes] Re: Replacement to DS1230AB Lithium backed NVRAM
To: TekScopes@...
Date: Sunday, March 17, 2013, 8:54 AM
Mr. Silva,
Its been a while. How is the 2465B going with FRAM ?
--- In TekScopes@..., "Victor Silva" <daejon1@...> wrote:
I have found that the FRAM devices are not a viable option in the
243X/40. Sadly I must report that what looked like a very promising
alternative to the DALLAS RAM/Lithium cell combo has turned out to be
a dead end.
I have been testing for over one month now on a 2430A, 2440 and 2465B
and everything seemed fine. My last test was to actually determine
the read/write frequency to the device.
It turn out a 2430A writes to the battery-backed devices as often as
once every microsecond. Since the FRAM device as a maximum of 10^10
read/write cycles (before it loses its NV capability) a quick
calculation reveals that the 2430A scope will render the FRAM device
a volatile device in one to three months.
For now I can only recommend the DALLAS (or other vendors)
RAM/Lithium cell combo pack device for use in Tek scopes.
Sorry for getting everyone's hopes up for a more inexpensive
replacement for NVRAM.
--Victor Silva
David Hess