# RE: [SI-LIST] : Any standards of the derating of Capacitors,Resit ors, and inducto rs?

From: ªL´Â·× ([email protected])
Date: Sun Mar 25 2001 - 19:50:53 PST

Dear Steve,
Could you please suggest how to derive the equation, you show below?

Series R power = ( ( Vswing / 2 ) ^ 2 / Rterm ) * Tflight * Symbol_rate. (
2 * Tflight cancels Symbol_rate / 2 )

Does somebody have any clues about the derivation of the equation?

Best Regards,

John Lin
Senior SI Engineer, Server Team, ARD4
Quanta Computer Inc.,Taiwan, R.O.C.
Email: [email protected]
Tel: 886+3+3979000 ext. 5183

-----Original Message-----
From: S. Weir [mailto:[email protected]]
Sent: Monday, March 19, 2001 4:47 PM
To: John Lin (ªL´Â·×)
Subject: Re: [SI-LIST] : Any standards of the derating of
Capacitors,Resitors, and inducto rs?

There are, but it depends primarily on the material and method of
construction. For example, tantalum capacitors voltage deratings are
typically 50%. You will have to get the data from the component mfg's that
you are qualifying.

Damping resistor power calculations depend on the circuit configuration.
For series termination schemes:

Series R power = ( ( Vswing / 2 ) ^ 2 / Rterm ) * Tflight * Symbol_rate. (
2 * Tflight cancels Symbol_rate / 2 )

Regards,

Steve.

At 03:46 PM 3/19/01 +0800, you wrote:

Dear SI gurus,

Are there any industrial standards for derating of capacitors and resistors,
as well as inductors?

For example, a capacitor rated as 10V, what shall be the proper operating
voltage applied to this capacitor in term of reasonable voltage stress
ratio? As we know, the higher operating voltage will cause lower MTBF (Mean
Team Between Failure). Thus, lower the reliability of products. However,
using higher rated capacitor will increase cost of products. The same things
happen to resistors and inductors.

Talking about the damping resistors, how do we calculate the power consuming
on them so that we can calculation power stress ratio, operating power
divided by rated power?

John Lin
Senior SI Engineer, Server Team, ARD4
Quanta Computer Inc.,Taiwan, R.O.C.
Email: [email protected]
Tel: 886+3+3979000 ext. 5183

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