Single bi-directional TVS = two uni-directional TVSs back to back ? - Page 1
Forum section: electronics / beginners

author: BravoV
author_rank: Super Contributor
timestamp: December 27, 2018, 08:58:44 am
content: I need 300V bi-directional TVS, but in hands only have the uni-directional version.As the forward voltage is insignificant compared to VBRwhich is at 300Volt, is this doable ?Max. power dissipation capability in that configuration is also doubled right ?

author: Zero999
author_rank: Super Contributor
timestamp: December 27, 2018, 10:06:15 am
content: A TVS diode behaves like an ordinary diode when forward biased so yes, connecting two unidirectional ones back-to-back will work.The maximum power dissipation is only doubled if the over-voltage is AC and has equal positive and negative components.https://www.mouser.com/pdfdocs/Semtech_Application_Note_TVS_Diode.pdf

author: tszaboo
author_rank: Super Contributor
timestamp: December 27, 2018, 11:30:42 am
content: Yes. I've seen people do this all the time. For example one chap was doing it for RS485, he had a 12V and a 7V TVS diode on it. Poor chap had no idea how to design circuits properly.

author: BravoV
author_rank: Super Contributor
timestamp: December 27, 2018, 05:38:48 pm
content: @Zero999 , thank you !Yes, its for AC , related to my other thread for building an AC soft starter for inductive load.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 27, 2018, 10:50:23 pm
content: In fact, the high voltage ones are typically stacks of ~30V parts -- they even build their SPICE models this way, and it gives more energy handling.Tim

author: BravoV
author_rank: Super Contributor
timestamp: December 28, 2018, 12:58:24 am
content: So each of them maxed out only at 30V ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 29, 2018, 01:34:36 am
content: Quote from: BravoV on December 28, 2018, 12:58:24 amEach of what?Each of the dies, it seems that way; but unless you're buying dies, I don't see that's a concern.Tim

author: BravoV
author_rank: Super Contributor
timestamp: December 29, 2018, 01:50:57 am
content: Quote from: T3sl4co1l on December 29, 2018, 01:34:36 amNo, not my concern, you just made me aware of it, thanks.Briefly at TVS datasheet, and looks like 30V dies stacking is at >= 200V.

author: spec
author_rank: Frequent Contributor
timestamp: December 29, 2018, 03:52:43 am
content: Hi BravoV300V bidirectional TVS here:https://www.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_p4sma_datasheet.pdf.pdfhttps://www.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_smaj_datasheet.pdf.pdfhttps://www.littelfuse.com/products/tvs-diodes/surface-mount/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_smcj_datasheet.pdf.pdfhttps://www.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_1_5smc_datasheet.pdf.pdfhttps://www.bourns.com/docs/Product-Datasheets/SMAJ.pdfhttps://www.bourns.com/docs/Product-Datasheets/SMBJ.pdf

author: BravoV
author_rank: Super Contributor
timestamp: December 29, 2018, 04:23:03 am
content: Spec, I am not looking for datasheets, thanks though.

author: spec
author_rank: Frequent Contributor
timestamp: December 29, 2018, 04:41:27 am
content: Quote from: BravoV on December 29, 2018, 04:23:03 amAh sorry. Misread your OP.