Quote:
Originally Posted by ChrisOddy
I've just programmed a few more Tesla PROM's whilst monitoring the data lines.
For most of the time the lines do not exceed 5V, for a short time around 15uS, there is a pulse up to 5.5V but it never goes higher than that.
I've now programmed quite a few chips on this programmer and haven't seen any ill effects (to the 8255).
Chris
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Hi Chris,
Is this because the esd diodes in the 8255 are clamping the voltage down to 5v?
The 8255 spec doesn’t specify a current limit for voltages avove the supply voltage. Just that the max input voltage is Vcc. So I’m not certain the 8255 has internal diodes.
Mark