I'm using a M48Z02, a 5 V 16 Kbit ZEROPOWER SRAM.
In absence of power, according to datasheet information, this device can hold data for years:
A [...] package houses the M48Z02 silicon with a long-life lithium button cell to form a highly integrated battery-backed memory solution.
The M48Z02 button cell has sufficient capacity and storage life to maintain data functionality for an accumulated time period of at least 10 years in the absence of power over commercial operating temperature range.
What I'm experiencing is a problematic data loss that make this chip untrustworthy.
I've created a small circuit using a stripboard to only read the M48Z02. I manage the circuit through an ON/OFF switch that connect the power source.
This schematic should explain:
About 5 hours ago I've programmed my SRAM and than inserted it into the stripboard manager. Now, when I wake it up it shows wrong data in some addresses.
Is possible that the battery failed and data were corrupted?
Is possible that some data were corrupted switching it on and off because of power pins are directly connected with control pins? If yes how avoid that?
NOTE: I presume that this isn't a problem about a buggy chip because 3 M48Z02 of mine have this problem.
What is a stripboard manager?
A "case" for the chip that helps to manage it:
b) When I say switch on/off I mean:
- my power source is OFF and the chip is in his case.
- I power ON the circuit
- after reading data I switch OFF the power source
- the chip is disconnected and (maybe) programmed again
c) About the heat:
I've noticed that when it fail or if I switch on/off power source frequently it becomes hot. Also it becomes very difficult to write new data on the device... but not impossible.
Any help you can provide will be really appreciated.