Looking for a voltage clamp IC.

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Pheetuz

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Hi folks, I am looking for an IC that I can use to protect a data bus from the outside world so to speak.
Basically the data bus is going to be connected to a possibly unstable environment and I need to protect against voltage spikes upto roughly 40V.

The data bus is connected to a PIC and therefore needs to be able to swing upto +5V and down to 0V.

So basically what I'm looking for is a voltage clamp from 0V to 5V that will not get damaged by voltages as high as 40V.

Any ideas are very much appreiciated.

/Pheetuz
 

The easiest way is to connect a pair of diodes from the data line to +5v and earth. one anode to earth, the other cathode to +5V. This way the energy is dissipated via the diodes/5V decoupling components. I would also put in series resistors (10 -100 ohm)from the input to the diodes. The problem is that your "40v spikes" could come from a low impedance source and their energy content could see off a diode. Same argument for an IC. Needs to dissipate real power and be "fast". You have not stated any speeds or durations of the spikes.
Frank
 
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