Hello. I have a few connectors on a design I am doing. I have put on TVS diodes on the pins of these connectors to protect them from ESD or other transients. However, my management wants me to put protection on the pins in case someone connects a constant voltage that is too high for the connector. For example, we have a USB connector with a maximum voltage of 7V before it damages the circuit. We have a TVS diode on it to protect from the ESD. However, we want to be able to protect it if someone connects a 12V constant supply to it. We want the voltage to not exceed 7V so that it would not damage the design. Are there any TVS diodes that I could get that would protect me from both transient voltages and constant voltages, or would I need to use both a Zener and TVS diode in my design?
Both MOVs and TVS diodes are adapted for dealing with events of short duration; they respond to hard-wired fault conditions like those described by changing color and releasing smoke.
Devices such as the TPS2400DBVT and NCV360SNT1G exist which are designed to help with this sort of thing. There are of course other options in that product family, as well as some (like these) in the specialized power management PMIC family that may also integrate further functionality.
A more rudimentary approach might incorporate a PTC resettable fuse in conjunction with a clamping-type OVP device, such as one based on thyristor technology. Given the limited margin between normal operating conditions and allowable maximums though, a solution with relatively precise characteristics (e.g. something integrated) would seem likely to be a good tradeoff.