Re: [SI-LIST] : Zener used to clamp Vcc?

About this list Date view Thread view Subject view Author view

From: Vinu Arumugham (vinu@cisco.com)
Date: Fri Feb 25 2000 - 14:56:31 PST


I have used such Zener diodes to protect the 5V devices against damage should an accidental short occur between 5V and a higher voltage supply during lab debug.

In one instance, we discovered that a lab DC supply was producing 12V spikes on its 5V output. After a few power cycles, the Zener diode would smoke. The 5V devices on the board were unharmed.

Vinu

Chris Bobek wrote:

> Hi,
>
> I was instructed to use a 5.6V Zener diode on the 5V Vcc plane of our
> board to clamp the voltage in the case of voltage spikes on the power
> supply. The Zener diode they chose is a 400mW diode. In your
> experience, is this the best way to handle power supply spikes? Is
> 400mW enough to accomplish anything? Our power supply is a 500W supply,
> I believe. The board typically draws 2A.
>
> I'm not sure what power supply spikes they are referring to. When I
> look at Vcc on a scope, the rising edge is a nice, quick, R-C charging
> curve. There's a lot of capacitance on our board and supply that
> dampens this response.
>
> Thanks for your help,
>
> Chris
>
> **** To unsubscribe from si-list or si-list-digest: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
> si-list archives are accessible at http://www.qsl.net/wb6tpu
> ****

**** To unsubscribe from si-list or si-list-digest: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
si-list archives are accessible at http://www.qsl.net/wb6tpu
****


About this list Date view Thread view Subject view Author view

This archive was generated by hypermail 2b29 : Thu Apr 20 2000 - 11:35:11 PDT