At 10:41 1999-01-11 -0700, you wrote:
>>When a spike enters on a pin the internal chip«s protection diodes will
>>deliver current to IC the supply; that might (will probably) cause a
>>damaging high voltage in the chip.  The zener is there to absorb that.
>>
>>(The chip will enter latch up first on currents above tens of mA through
>>the diodes, or mayby at hight overvoltage.)
>>
>>
>>Oh, I forgot to mention that you need serial resistors on the control
>>signals, of course, approx 10kohm.
>
>
>What would these be for?

When/if the 4051 go into latch-up, or get destroyed, the 4051 would else
draw much current through the control lines.

Another scenario is that a strong spike goes througt the 4051 into the
controller, maybe not damaging it, but confusing it, or througt the
controllers protection diodes delivering a spike to that one«s Vdd.

/Morgan

>Gabriel
>
>>
>>/Morgan
>
>
        Morgan Olsson                   ph  +46(0)414 70741
        MORGANS REGLERTEKNIK            fax +46(0)414 70331
        H€LLEKS           (in A-Z letters: "HALLEKAS")
        SE-277 35 KIVIK, SWEDEN               mrt@iname.com
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