Timeline for Unidirectional or Bi-directional TVS diodes - Which one to use?
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
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| Sep 12, 2023 at 10:56 | comment | added | Kartman | @Freshman theoretically no more than -0.7V but if you look at the specs it is dependent on the current. Similarly with the positive voltage the clamp voltage can be much higher than the advertised voltage. Real components are rarely as good as you’d hope them to be, this is why you need to read the datasheets closely. | |
| Sep 11, 2023 at 8:55 | comment | added | Freshman | @Klas-Kenny, in that case, if the TVS is placed on the power supply VBUS line, in the case of negative transient on the power supply line, the voltage on the line would not be more than the forward voltage drop of the diode right, (say Vf of TVS diode is 0.7V. Since, it is for negative transient, the voltage would not be more than -0.7V on the power supply line, right)? | |
| Sep 11, 2023 at 8:51 | comment | added | Freshman | @Klas-Kenny, thank you for the comment/clarification for this answer. So, for power lines or , to be more general/specific, if the voltage on a line is positive, then unidirectional diode is sufficient. If the voltage on a line can be positive or negative wrto ground, the bidirectional diode is required. Am I correct? | |
| Sep 11, 2023 at 8:49 | vote | accept | Freshman | ||
| Sep 11, 2023 at 8:50 | |||||
| Sep 11, 2023 at 8:42 | comment | added | Klas-Kenny | I don't agree with this answer. It is not whether the overvoltage can occur as both positive or negative (since we are mainly talking about ESD here, that would always be the case, rendering unidirectional pretty much useless). It is whether the signal voltage can be both positive and negative or not. For USB, that would not be the case, signal voltages are always positive with regard to ground so unidirectional TVS is sufficient (unless you intend to place it between D+ and D- for whatever reason). | |
| Sep 11, 2023 at 7:53 | comment | added | Antonio51 | I think the pin's voltages are always "positive", although it can be 5V ... 12 V, or perhaps "more". | |
| Sep 11, 2023 at 7:41 | comment | added | Freshman | Thank you for the answer. So, since, for USB connectors/receptacles, we do not know whether we will get a positive overvoltage or negative overvoltage on the pin, you say a single unidirectional TVS diode would be sufficient? | |
| Sep 11, 2023 at 7:32 | history | answered | Antonio51 | CC BY-SA 4.0 |