Greetings friends,

Has anyone had much time to investigate the 12C508?  I am doing some timing
with it (range 290mS to 4.4 Seconds) and have noticed that the internal RC
clock isn't even close to the 4 MHZ target.  That datasheet parameters say
that at 5 Volts, 25 degrees C the clock should be about 4.2 MHz, but my
results with a JW part are about 4.95 MHz.  Can anyone think of what might
cause this?  Of course, I can fib in the delay routines and make it delay
exactly what I want, but who knows if this is just an odd batch and the
OTP's will be on target?  Date code is 9648.  Are the JW's just faster than
the OTP's (this doesn't seem right to me as it is the same die exactly).  I
won't have any OTP's for several days so I can't test it that way, and YES I
have tried it with an opaque window covering. Vdd is 4.99 volts, room
temperature.  Chip is cold, so no self heating I believe.  I see that every
step in the Calibration Constant moves the perion 4nS, so there's no way
that can account for the deviation, even though I am moving this value into
OSCAL correctly.

In addition, anyone else finding the JW version hard to get ahold of?  I
guess they are moving pretty fast!  HAHAHA, get it? FAST?


        -Todd Peterson

P.S. - Even if the internal RC oscillator stayed within the specs in the
book, I cannot see the internal oscillator being used at any reasonable
speed for RS-232; anyone have any thoughts or opinions/data on this?  I
think I2C will work, as that is not so clock-speed critical, is it?