galahad

Current injection / Port pins HC08 HCS08

Discussion created by galahad on Jan 11, 2008
Latest reply on Jan 20, 2008 by galahad
Hello,
 
it was some kind of a shock for us  to see that newer chips of the HC08 (QC) and most (all?) of the HCS08 have a much smaller limit for current injection on port pins.
 
The limit for HC08 was usually +-2mA
Newer chips now tolerate only 0.2mA
 
We used 220..470 Ohm resistors to protect ports for years, we never had problems. In many of our our applications you might reverse a connector, and then about 5V are at the port pins without any supply to the MCU. Again, so far no chip failed.
 
But with 0.2mA this seems to be far more dangerous. We stopped a MC9S08GT16 design already and will use a good old (but expensive) MC908GR16 instead.
 
Any comments or experiences? Thank you!

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