I decided to try a little experiment on my 3457A, When on mains the SRAM gets 4.8 ~ 5 V. This does not seem to be well regulated, so I assume depends on mains voltage. Once power is removed, the voltage on the SRAM stays well above the battery voltage for some considerable time, which I assume is due to a decoupling capacitor. My 10 M Ohm input Z multimeter is loading the circuit too much to continuously monitor the voltage, but a few checks indicated the voltage across the SRAM is falling quite slowly. Starting at 4.8 V from mains power, after 23 minutes of no mains power, the voltage on the SRAM was at 3.4V, which is above the battery voltage (3.03 V). and well above the 2.0 V needed to hold the SRAM contents. Assuming the SRAM takes a constant current one would expect the voltage to fall linearly with time. If so, it would take 46 minutes to fall to 2.0 V even without battery power.
ESD and leakage of the human body would probably make screw this up, so I'm not suggesting replacing the battery that way if you want to preserve the contents of the SRAM, but there's a fairly good chance the contents would remain in RAM if one was reasonably quick, especially if you topped the voltage up from the mains just before removing it from the chassis. Dr. David Kirkby Ph.D CEng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK. Registered in England and Wales, company number 08914892. http://www.kirkbymicrowave.co.uk/ Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please) _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
