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Quick TVS diode question. Vclamp < Vbreakdown

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T3sl4co1l:
Hmm, minimum rating is -60V, you'll have to do something about that. Can you not afford a series diode?

Tim

kellogs:
Is the LT4356 not going to survive -220 shocks because of its GND, TMR and FB connections ?

Series diodes get hot really quickly at my amperage, and device will be mounted in crammed hot place already.

T3sl4co1l:
Maybe just use the "passive" PMOS polarity protection thing in front, not integrating it with the LT chip.

Also, again, you're worrying about 220V like the terminal is going to reach -220.00V with respect to ground? You know what impedance means right?  It's not plugging into mains here.

Tim

kellogs:
220V PMOS @8A would be worse than series diodes... best I could find was Rds_on of 0.5 ohm (typical value)

Hmm, impedance, let me check - Ri = 50 ohm and Us = -220V, in series with all of the grounded surge stopper IC pins... no, in series with...  :-//
But why do they say protection up to -80V if the chip itself can only do -60V ? Page 21 here, first diagram titled "Overvoltage Regulator with Reverse Input Protection Up to –80V"
Side note, those IRLR2908 are rated to 80V.



 

T3sl4co1l:
Yeah like that. Note also 2N3904 rating. Or MMBT3904 more likely.  1N914 for that matter.


--- Quote from: kellogs on September 18, 2022, 01:41:16 pm ---But why do they say protection up to -80V if the chip itself can only do -60V ?

--- End quote ---

Vin doesn't directly touch any IC pins...

Tim

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