[SI-LIST] Re: Query on ESD protection for USB 2.0 signals
- From: "Pommerenke, David" <davidjp@xxxxxxx>
- To: "Charles.Grasso@xxxxxxxxxxxx" <Charles.Grasso@xxxxxxxxxxxx>, "chundis@xxxxxxxxx" <chundis@xxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
- Date: Wed, 25 Feb 2015 16:16:26 +0000
Srikanth,
Of course, you can select a TVS diode that has the lowest "turn on" voltage and
the lowest dynamic resistance for both polarities, having a capacitance that
will not affect SI too much. But a much better process is to understand the
interaction between the transient behavior of the TVS diode, the connecting
traces and the transient behavior of the ESD protection (including its damage
limit) of the IC. If you have the information and run some SPICE simulations
you will be able to optimize the design and you can be sure it works.
The main risk in just selecting some TVS is that the ESD protection of the IC
may "protect" the TVS, as its VI curve of the IC maybe above the VI curve of
the TVS diode, so the IC takes the current and limits the voltage. For that
reason many varactor's and most non linear polymer devices will not be suitable.
David Pommerenke
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Grasso, Charles
Sent: Wednesday, February 25, 2015 9:48 AM
To: chundis@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Query on ESD protection for USB 2.0 signals
Hi Sritkath, One characteristic to look for is the dynamic resistance of the
diode (amongst others). The lower the better.
Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042974@xxxxxxxxx
(e) charles.grasso@xxxxxxxxxxxx
(e2) chasgrasso@xxxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Chundi Srikanth
Sent: Tuesday, February 24, 2015 10:50 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Query on ESD protection for USB 2.0 signals
Hi Techies,
I have a question on USB2.0 ESD protection. What is the main criteria to see in
selecting a ESD protection device? There are lot of vendors who are providing
these solutions with VBUS up to 15V clamping, Data signals upto 5.5V clamping
and some other mentions that they have the Lowest clamping voltage of 6V and
with lowest capacitance. Which one to choose? whether with lowest clamping
voltage or with the highest one?
Please clarify.
Thank You.
Regards
Srikanth
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