[SI-LIST] Re: ppm(parts per million)-Crystal OSC

• From: "Jayaprabakaran" <jayaprabakaran.k@xxxxxxxxxxxxxxxxxxx>
• To: "'vikas dhanda'" <vikasdhanda7@xxxxxxxxx>, <hilal@xxxxxxxxxxxxxxxx>
• Date: Thu, 15 Dec 2011 14:15:18 +0530

```Hi Hilal and Vikas,

Thanks for the clarification.

Regards,

Jp

_____

From: vikas dhanda [mailto:vikasdhanda7@xxxxxxxxx]
Sent: Thursday, December 15, 2011 1:14 PM
To: Jayaprabakaran
Cc: si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] Re: ppm(parts per million)-Crystal OSC

Frequency tolerance (in ppm)=>The Frequency Tolerance of a crystal or
oscillator is defined as the initial deviation of the crystal or oscillator
frequency as compared to the absolute at 25°C like it designed for 25Mhz but
measured is 24.999946Mhz So this is the frequency tolerance.

Where the

Frequency stability is the frequency deviation compared to the measured
frequency at 25°C over the defined operating temperature and voltage
range.Here we consider 24.999946Mhz as actual frequency (as Measured) and
calculate PPM with this Frequency but don't consider  25Mhzfor calculation.

Regards,

Vikas Dhanda

On Thu, Dec 15, 2011 at 10:25 AM, Jayaprabakaran
<jayaprabakaran.k@xxxxxxxxxxxxxxxxxxx> wrote:

Most of the crystals have two ppm values.
Frequency tolerance (in ppm) and Frequency stability (in ppm).
What are the difference b/w two parameters?

Regards,
Jayaprabakaran

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On

Behalf Of Mike Poorman (Cascade Engineering Svcs Inc)
Sent: Wednesday, December 14, 2011 11:22 PM
To: 'si-list@xxxxxxxxxxxxx'
Subject: [SI-LIST] Re: ppm(parts per million)-Crystal OSC

Think of PPM as a tolerance on the frequency.  The smaller the PPM number
the more accurate and stable the crystal frequency will be.

Mike Poorman
EMC Technician
Email:  v-mipoor@xxxxxxxxxxxxx

This email message may contain confidential and proprietary information.
Any unauthorized use is prohibited.  If you are not the intended recipient,
original message.

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of bala
Sent: Wednesday, December 14, 2011 2:17 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] ppm(parts per million)-Crystal OSC

Hi all,
I have a little confusion on PPM vs frequency of Crystal Oscillators.How
important is the term 'ppm' than frequency.Why all the datasheets have both
units,ppm and Hz.Please clarify,Also how much important is the value of ppm
on the Signal integrity side,if any.Thanks for your time.

--
bala

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