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Date: Tue, 26 Jan 2021 14:36:52 -0800
Subject: Re: [EE] RS485 ESD protection
Thread-Topic: [EE] RS485 ESD protection
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Well, the 7kV protection is HBM (Human Body Model) ESD, whereas the 60V
is ground differential, rather different things.

i would agree that some form of TVS unit is likely to be useful,
although I doubt it would be full protection against ground bounce
problems - that would only get cured by isolation.

As to what TVS devices to use, Bourns seem to be a major player in this
area, with devices for protecting USB ports and the like which would be
the sort of devices I would use.


On Tue, 26 Jan 2021 22:07:20 +0000
John Lawton <piclist@jle.co.uk> wrote:

> The LTC2862A has headline '7kV protection' but in fact only +/-60V
> for 'line faults'.
>=20
> Also, in the case of the lighting control board was there a common=20
> connection?
> If not then a large potential difference between the common lines
> could also cause failure.
>=20
> Some additional TVS diodes could be used to help protect against the
> above.
>=20
> John
>=20
>=20
> On 26/01/2021 21:25, Neil wrote:
> > Anyone have a favourite part or circuit-section for very good RS485
> > ESD/voltage-spike protection?
> >
> > I'm re-designing a lighting control board for someone and they've
> > fried a handful of RS485 interfaces in the past.  Those chips had
> > 7kV of protection.
> > We have no practical way to measure the ESD, but I want to make
> > this a protected as possible... only a handful of boards will be
> > built, so let's assume cost no issue for now.
> >
> > Any thoughts on this (LTC2862)?...
> > https://www.analog.com/media/en/technical-documentation/data-sheets/286=
2af.pdf
> > And with these, does it help to add TVS'es as well?  What about a
> > digital isolator between the RS85 interface chip and the
> > microcontroller?
> >
> > Thanks.
> >
> >
> > =20
>=20

--=20
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