 If your Sega Saturn is anything like mine then it devours CR2032 cells like there's no tomorrow. This has the annoying result of wiping any save data that was held on the console. You can tell the battery has been drained when the console asks you to re-enter the time and date settings on power up.  The problem is that there is too large of a current drain on the CR2032 (backup battery). Two things are powered by the backup battery when the console is powered down: the backup SRAM and the system's real-time clock (RTC). As of now I can't tell which of the two is causing the major drain on the battery.  I recently stumbled upon a schematic of the Sega Saturn, I quickly searched to find the concerned areas (Backup SRAM and RTC). The Saturn's RTC is contained within the System Manager IC so there's no hope of swapping it for a lower-power version. Luckily however, the Backup SRAM is a discrete 28-SOIC chip. Whether or not the SRAM is the power culprit is unsure, but a quick investigation made me realize that this SRAM has a standard pinout and is pin compatible with a FM28V020-SG 32KB FRAM chip. FRAM, which stands for Ferroelectric RAM, is a random-access memory similar in construction to DRAM but uses a ferroelectric layer instead of a dielectric layer to achieve non-volatility. In layman's terms, it retains data without power - this particular chip is rated for 150+ years of data retention! I haven't yet tried to drop this chip in the Sega Saturn but all current investigation points to it working. There would be no other modification necessary to the circuit. For me, I would simply omit the battery from now on - I don't really care if my Saturn doesn't hold current time (as long as my save files are always present). FRAM is very expensive relative to other memory types. However, for a console mod which will save me headaches I think it's worth it. I'll be ordering one of these FRAM chips on my next Digikey order and will post the results on here. RPG's - here I come! |
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