I'm trying to protect a component against ESD strikes - this component is particularly sensitive, so I am also trying to protect against sub-ns strikes. Forward voltage (max allowable) is 8V, reverse is 2V. Normally operated at 7V.
The normal approach would be to specify a ESD specific unidirectional TVS connected in parallel as close to this component as possible. One with vary fast transient response.
Another might be to use a high speed varistor (such as TDK Ceradiode, claimed <0.5ns response), however this is bi-directional and the clamping voltage may be a little high.
The addition of a ceramic capacitor in parallel may also help absorb some of the excess energy.
After chatting with someone on this topic, they insisted that schottky diode connected anti parallel is the best solution - their claim 'nothing is faster' might be true but I have three concerns:
- Schottky diodes may actually be damaged by these transients themselves.
- It will only protect against ESD strikes in the one direction.
- The forward voltage of a Schottky may be lower, but will it actually be quicker or perform (responsiveness / clamping below 2V) any better than a TVS diode built for the job such as this? (in the one direction).
The forward voltage of unidirectional TVS's don't seem to be specified either.
I'm interested to hear what people think about each of the points above - especially if there would be any benefit at all to using a Schottky in combination with the above.