In addition to what Markfrizb said...
No. It depends on context. The overvoltage protection diodes on a lot of parts are rated to exactly 0.3V, and not more, without damage.BennVenn wrote:for an average silicon diode [the forward voltage] is 0.6 volts.
[schematic showing a forward voltage of 0.6V on the overvoltage protection diodes inside a 3.3V part]
One clever trick [bootleg manufacturers] use is to add a diode inline with the supplyNewer releases, yes, after the initial kerfluffle. There were a large number of earlier carts manufactured using explicit 3.3V regulators, or stacks of diodes dropping the voltage down to 3.2-3.8V.
edit: And to be clear, your initial video showed exactly the problematic situation, putting a 3V flash and a 3V regulator on a daughterboard by itself without any care as to how that flash interacted with the outside world.
this drops the five volts down to 4.4 volts, which is just within the safe operating area of the flash chipThe MX29GL256 pictured on that board has an Absolute Maximum Rating of 4.0V for VCC and VI/O. 4.4V is not guaranteed to be safe for the flash chip. Furthermore, diodes make awful voltage "regulators" and the voltage seen by the part will swing from 4.4V to 5V depending on the instantaneous (or average, if there's a capacitor) current drawn by the flash.
Powering the flash at 4.4V means that a 5V input will conduct through this diode and no current will flow into the supplyOnly if the diode used externally is matched to the overvoltage diodes on the part.
So, can a cheap bootleg cart put your console at risk? The answer is no.The answer is "it @%&(!@$* depends" and saying "don't worry" is worse than saying "I'm confident that my design is safe".
In general, if there's no voltage regulator, the 3.3V-rated parts may die at some point in the future, but the console is probably safe. If there is a voltage regulator, and you aren't explicitly using parts that are 5V tolerant or adding 5V translation, it will damage the console.