Looking to build a board for a cool new project. I'm not too familiar with chips, I usually use 27C322 chips, but I need something smaller to fit in the case I'm building, as the 27c322's height is too high. Is there any chip I could use with a lower height, flash maybe? The current PCB I have runs a 27C322 pinout and the file is 4MB, I don't want to have to send out and get another board made.
Maybe a MX 29L3211? I know I'd have to wire it by hand, or make another adapter by hand (Scratch board).
Thanks,
Looks like both can do [4M x 8/2M x 16], so, I should be able to. Looks like I would need a 3.3 regulator for the ML eeprom. Thanks guys/girls.
Do not use a 3V part on a 5V system without adding voltage translation! It will damage the part and/or the system.
There are no currently-manufactured 4 MiB 5V PROMs. You might be able to get some older ones (either New-Old-Stock or part pulls) but I'm not having much luck finding them.
The largest 5V parallel NOR PROMs made right now is Micron's 2 MiB M29F160 and Macronix's 1MiB MX29F800; both are surface mount.
The cheapest overvoltage protection seems to be the GTL2000 series of MOSFET voltage clamps.
lidnariq wrote:
Do not use a 3V part on a 5V system without adding voltage translation! It will damage the part and/or the system.
There are no currently-manufactured 4 MiB 5V PROMs. You might be able to get some older ones (either New-Old-Stock or part pulls) but I'm not having much luck finding them.
The largest 5V parallel NOR PROMs made right now is Micron's 2 MiB M29F160 and Macronix's 1MiB MX29F800; both are surface mount.
The cheapest overvoltage protection seems to be the GTL2000 series of MOSFET voltage clamps.
Correct, with a 3.3 regulator between the chip and the PCB, it should take care of that correct?
Similar to what mmmonkey did here?
http://www.mmmonkey.co.uk/star-ocean-translated-cart/
Nope! You need to add voltage translation, not just the voltage regulator. Otherwise the SNES's address and data lines will be constantly stressed by sourcing current into the 3V part, and the 3V's overvoltage protection diodes are constantly being used. (Depending on the exact topology of the 3V regulator, it may also raise the operating voltage of the ROM above its rated range, in which case it will cause much more rapid failure of the ROM) This is bad for both the ROM and the SNES, so don't do that.
The 3V voltage regulator only supplies 3V to the positive voltage supply of the chip. It also sets the output-high voltage of that chip. What it *doesn't* do, is change the input-high voltage (aka, the voltage generated by the other parts in the system when they are output-high). So any time the system outputs a high bit, you are applying 4.5-ish volts to that I/O pin, which is too high for the chip. Also, if the chip contains clamping diodes, the excess voltage gets fed back onto the 3V power rail, which can then blow the whole chip. There is also the issue that for some 5V systems, 3V is not high enough to consistently be read as a 1 (or rather, 3V is the bare minimum threshold for a valid 1, but the 3V chip might be outputting as low as 2.4V). So you have to step down the 5V logic signals in order to not blow up the 3V chip, and you also have to step up the 3V signals in order for them to be read properly. You have to do that for every I/O pin.