Measurement of quartz crystal unit parameters - Part 6: Measurement of drive level dependence (DLD)

IEC 60444-6:2013 applies to the measurements of drive level dependence (DLD) of quartz crystal units. Two test methods and one referential method are described. This edition includes the following significant technical changes with respect to the previous edition:
a) DLD measurement with oscillation circuit had the traditional method to detect the DLD abnormal modes at present time. Therefore, this method made the transition to the Annex B.
b) High reliability crystal unit is needed to use for various applications at the present day, in order to upgrade the inspection capabilities for DLD abnormal modes, the multi-level reference measurement method was introduced into this specification.

Mesure des paramètres des résonateurs à quartz - Partie 6: Mesure de la dépendance du niveau d'excitation (DNE)

La CEI 60444-6:2013 s'applique aux mesures de la dépendance du niveau d'excitation (DNE) des résonateurs à quartz. Deux méthodes d'essai et une méthode de référence sont décrites. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) La mesure de DNE avec le circuit oscillation utilisait la méthode traditionnelle de détection des modes anormaux DNE au temps présent. Donc, cette méthode fait la transition avec l'Annexe B.
b) La grande fiabilité de l'unité de cristal utilisé est nécessaire pour diverses applications actuelles, pour permettre de mettre à jour les capacités d'inspection des modes anormaux des DNE, la méthode de mesure de référence de multi-niveaux a été présentée dans cette spécification.

General Information

Status
Published
Publication Date
18-Jun-2013
Current Stage
DELPUB - Deleted Publication
Completion Date
01-Sep-2021
Ref Project

Buy Standard

Standard
IEC 60444-6:2013 - Measurement of quartz crystal unit parameters - Part 6: Measurement of drive level dependence (DLD)
English and French language
38 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

IEC 60444-6
Edition 2.0 2013-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measurement of quartz crystal unit parameters –
Part 6: Measurement of drive level dependence (DLD)
Mesure des paramètres des résonateurs à quartz –
Partie 6: Mesure de la dépendance du niveau d'excitation (DNE)
IEC 60444-6:2013
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2013 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form

or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from

either IEC or IEC's member National Committee in the country of the requester.

If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,

please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni

utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les

microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.

Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette

publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé Fax: +41 22 919 03 00
CH-1211 Geneva 20 info@iec.ch
Switzerland www.iec.ch
About the IEC

The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes

International Standards for all electrical, electronic and related technologies.
About IEC publications

The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the

latest edition, a corrigenda or an amendment might have been published.
Useful links:

IEC publications search - www.iec.ch/searchpub Electropedia - www.electropedia.org

The advanced search enables you to find IEC publications The world's leading online dictionary of electronic and

by a variety of criteria (reference number, text, technical electrical terms containing more than 30 000 terms and

committee,…). definitions in English and French, with equivalent terms in

It also gives information on projects, replaced and additional languages. Also known as the International

withdrawn publications. Electrotechnical Vocabulary (IEV) on-line.

IEC Just Published - webstore.iec.ch/justpublished Customer Service Centre - webstore.iec.ch/csc

Stay up to date on all new IEC publications. Just Published If you wish to give us your feedback on this publication

details all new publications released. Available on-line and or need further assistance, please contact the

also once a month by email. Customer Service Centre: csc@iec.ch.
A propos de la CEI

La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des

Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI

Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez

l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
Liens utiles:

Recherche de publications CEI - www.iec.ch/searchpub Electropedia - www.electropedia.org

La recherche avancée vous permet de trouver des Le premier dictionnaire en ligne au monde de termes

publications CEI en utilisant différents critères (numéro de électroniques et électriques. Il contient plus de 30 000

référence, texte, comité d’études,…). termes et définitions en anglais et en français, ainsi que

Elle donne aussi des informations sur les projets et les les termes équivalents dans les langues additionnelles.

publications remplacées ou retirées. Egalement appelé Vocabulaire Electrotechnique

International (VEI) en ligne.
Just Published CEI - webstore.iec.ch/justpublished
Service Clients - webstore.iec.ch/csc
Restez informé sur les nouvelles publications de la CEI.

Just Published détaille les nouvelles publications parues. Si vous désirez nous donner des commentaires sur

Disponible en ligne et aussi une fois par mois par email. cette publication ou si vous avez des questions

contactez-nous: csc@iec.ch.
---------------------- Page: 2 ----------------------
IEC 60444-6
Edition 2.0 2013-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measurement of quartz crystal unit parameters –
Part 6: Measurement of drive level dependence (DLD)
Mesure des paramètres des résonateurs à quartz –
Partie 6: Mesure de la dépendance du niveau d'excitation (DNE)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX R
ICS 31.140 ISBN 978-2-83220-876-2

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – 60444-6  IEC:2013
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope ............................................................................................................................... 6

2 Normative references ....................................................................................................... 6

3 DLD effects ...................................................................................................................... 6

3.1 Reversible changes in frequency and resistance ..................................................... 6

3.2 Irreversible changes in frequency and resistance .................................................... 6

3.3 Causes of DLD effects ............................................................................................. 7

4 Drive levels for DLD measurement ................................................................................... 7

5 Test methods.................................................................................................................... 8

5.1 Method A (Fast standard measurement method) ..................................................... 8

5.1.1 Testing at two drive levels ........................................................................... 8

5.1.2 Testing according to specification ................................................................ 8

5.2 Method B (Multi-level reference measurement method) ........................................... 9

Annex A (normative) Relationship between electrical drive level and mechanical

displacement of quartz crystal units ...................................................................................... 11

Annex B (normative) Method C: DLD measurement with oscillation circuit ........................... 14

Bibliography .......................................................................................................................... 19

Figure 1 – Maximum tolerable resistance ratio γ for the drive level dependence as a

function of the resistances R or R ...................................................................................... 9

r2 r3

Figure B.1 – Insertion of a quartz crystal unit in an oscillator ................................................ 14

Figure B.2 – Crystal unit loss resistance as a function of dissipated power ........................... 15

Figure B.3 – Behaviour of the R of a quartz crystal units ...................................................... 16

Figure B.4 – Block diagram of circuit system ......................................................................... 16

Figure B.5 – Installed −R in scanned drive level range ..................................................... 17

osc

Figure B.6 – Drive level behavior of a quartz crystal unit if −R = 70 Ω is used as

osc

test limit in the “Annex B” test ............................................................................................... 17

Figure B.7 – Principal schematic diagram of the go/no-go test circuit .................................... 18

---------------------- Page: 4 ----------------------
60444-6  IEC:2013 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASUREMENT OF QUARTZ CRYSTAL UNIT PARAMETERS –
Part 6: Measurement of drive level dependence (DLD)
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 60444-6 has been prepared by lEC technical committee 49:

Piezoelectric, dielectric and electrostatic devices and associated materials for frequency

control, selection and detection.

This second edition cancels and replaces the first edition published in 1995. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

a) DLD measurement with oscillation circuit had the traditional method to detect the DLD

abnormal modes at present time. Therefore, this method made the transition to the

Annex B.

b) High reliability crystal unit is needed to use for various applications at the present day, in

order to upgrade the inspection capabilities for DLD abnormal modes, the multi-level

reference measurement method was introduced into this specification.
---------------------- Page: 5 ----------------------
– 4 – 60444-6  IEC:2013
The text of this standard is based on the following documents:
CDV Report on voting
49/1004/CDV 49/1038/RVC

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 60444 series, published under the general title Measurement of

quartz crystal unit parameters, can be found on the IEC website.
---------------------- Page: 6 ----------------------
60444-6  IEC:2013 – 5 –
INTRODUCTION

The drive level (expressed as power/voltage across or current through the crystal unit) forces

the resonator to produce mechanical oscillations by way of piezoelectric effect. In this process,

the acceleration work is converted to kinetic and elastic energy and the power loss to heat.

The latter conversion is due to the inner and outer friction of the quartz resonator.

The frictional losses depend on the velocity of the vibrating masses and increase when the

oscillation is no longer linear or when critical velocities, elongations or strains, excursions or

accelerations are attained in the quartz resonator or at its surfaces and mounting points (see

Annex A). This causes changes in resistance and frequency, as well as further changes due

to the temperature dependence of these parameters.

At “high” drive levels (e.g. above 1 mW or 1 mA for AT-cut crystal units) changes are

observed by all crystal units and these also can result in irreversible amplitude and frequency

changes. Any further increase of the drive level may destroy the resonator.

Apart from this effect, changes in frequency and resistance are observed at “low” drive levels

in some crystal units, e.g. below 1 mW or 50 µA for AT-cut crystal units). In this case, if the

loop gain is not sufficient, the start-up of the oscillation is difficult. In crystal filters, the

transducer attenuation and ripple will change.

Furthermore, the coupling between a specified mode of vibration and other modes (e.g. of the

resonator itself, the mounting and the back-fill gas) also depends on the level of drive.

Due to the differing temperature response of these modes, these couplings give rise to

changes of frequency and resistance of the specified mode within narrow temperature ranges.

These changes increase with increasing drive level. However, this effect will not be

considered further in this part of IEC 60444.

The first edition of IEC 60444-6 was published in 1995. However, it has not been revised until

today. In the meantime the demand for tighter specification and measurement of DLD has

increased.

In this new edition, the concept of DLD in IEC 60444-6:1995 is maintained. However, the

more suitable definition for the user’s severe requirements was introduced. Also, the

specifications based on the matters arranged in the Stanford meeting in June, 2011 are taken

into consideration.
---------------------- Page: 7 ----------------------
– 6 – 60444-6  IEC:2013
MEASUREMENT OF QUARTZ CRYSTAL UNIT PARAMETERS –
Part 6: Measurement of drive level dependence (DLD)
1 Scope

This part of IEC 60444 applies to the measurements of drive level dependence (DLD) of

quartz crystal units. Two test methods (A and C) and one referential method (B) are described.

“Method A”, based on the π-network according to IEC 60444-1, can be used in the complete

frequency range covered by this part of IEC 60444. “Reference Method B”, based on the π-

network or reflection method according to IEC 60444-1, IEC 60444-5 or IEC 60444-8 can be

used in the complete frequency range covered by this part of IEC 60444. “Method C”, an

oscillator method, is suitable for measurements of fundamental mode crystal units in larger

quantities with fixed conditions.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and

are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any
amendments) applies.

IEC 60444-1, Measurement of quartz crystal unit parameters by zero phase technique in a π-

network – Part 1: Basic method for the measurement of resonance frequency and resonance

resistance of quartz crystal units by zero phase technique in a π-network

IEC 60444-5, Measurement of quartz crystal units parameters – Part 5: Methods for the

determination of equivalent electrical parameters using automatic network analyzer

techniques and error correction

IEC 60444-8, Measurement of quartz crystal unit parameters – Part 8: Test fixture for surface

mounted quartz crystal units
3 DLD effects
3.1 Reversible changes in frequency and resistance

Reversible changes are changes in frequency and resistance occurring under the same drive

levels after repeated measurements made alternatively at low and high levels, or after

continuous or quasi-continuous measurements from the lowest to the highest level and back,

if these changes remain within the limits of the measurement accuracy.
3.2 Irreversible changes in frequency and resistance

Irreversible changes are significant changes in frequency and/or resistance occurring at low

level after an intermediate measurement at high level e.g. when a previously high resistance

at low level has changed in the repeated measurement to a low resistance. Especially, when

the crystal unit has not been operated for several days, its resistance may have changed back

to a high value when operated again at a lower level. Greater attention should be paid to the

irreversible effect since it can significantly impair the performance of devices, which are

operated only sporadically.
---------------------- Page: 8 ----------------------
60444-6  IEC:2013 – 7 –
3.3 Causes of DLD effects

Whereas the mostly reversible effects are due to excessive crystal drive level, the irreversible

effects are due to production, especially to imperfect production techniques. Examples of

causes are:

– Particles on the resonator surface (partly bound by oils, cleaning agents. solvents or

bound electro-statically);

– Mechanical damage of the resonator (e.g. fissures due to excessively coarse lapping

abrasive which may increase in size);

– Gas and oil inclusions in the electrodes (e.g. due to a poor vacuum or an inadequate

coating rate during evaporation);

– Poor contacting of the electrodes at the mounting (e.g. the conductive adhesive has an

inadequate metal component, was insufficiently baked out or was overheated; also

excessive contact resistance between the conductive adhesive and the electrodes or

mounting);
– Mechanical stresses between mounting, electrodes and quartz element.
4 Drive levels for DLD measurement

For the DLD measurement, a low and a high level of drive (and possibly further levels) are

applied. The high level is the nominal drive level, which should be equal to the level in the

application at its steady state.

It should be noted that this level should be below the maximum applicable level that is derived

in Annex A. If not specified, a standard value for the crystal current of 1 mA, corresponding to

the velocity v max = 0,2 m/s for AT-cut crystal units, shall be used. The drive level in watts is

then calculated with the mean value of the specified maximum and minimum resistances.

The minimum drive level occurring at the start-up of an oscillator can be determined only in a

few cases by active or passive measuring methods due to the noise limits of the measuring

instruments for measurements according to IEC 60444-1, at approximately 1 nW or 10 µA

(depending on the equipment, the lowest power value can be reduced to 0,1 nW or 1 µA).

A velocity v max = 0,01 m/s, corresponding to 50 µA for AT-cut crystals, has proved to be

practical value for π-network measurements (see “Method A”).

In the following, two methods and one referential method of DLD measurement are described.

“Method A” is based on the π-network method according to IEC 60444-1, which can be used

in the complete frequency range covered by this standard. It allows the fast selection of drive

level sensitive quartz crystal units by a sequence of three measurements. The allowed

variation of the resonance resistances given in Figure 1 is based on long-term examinations

of crystal units of different manufacturers and proved to be a reliable indicator for crystal units

showing start-up problems. If necessary, this method should also is extended by measuring a

large number of different drive levels. However, in practice, this is not necessary in most

cases (see 5.1).

“Method B” is used for devices where strict oscillation start-up requirements have to be

fulfilled and for high reliability devices.

“Method C” in Annex B is an oscillator method, which is especially suitable for measuring

fundamental mode crystal units in larger quantities with fixed measurement conditions

(maximum drive level, R max) in an economical way.

If the proposed measurement techniques are not sufficient in special cases, the user should

have an original oscillator with slightly reduced feedback or an original filter.

---------------------- Page: 9 ----------------------
– 8 – 60444-6  IEC:2013
“Method B” is stricter than “Method A”.

“Method B” is based on the π-network method or reflection method according to IEC 60444-1,

IEC 60444-5 or IEC 60444-8, which can be used in the complete frequency range covered by

this standard.
Recommendation: These methods can be used for all types of crystals, however:
– “Method A” is recommended for filter and oscillator crystals.

– “Method B” is recommended for applications with strict start-up conditions, for high

reliability and for high stability applications. It is the reference method for failure analysis

etc.

– “Method C” in Annex B is a go/no-go measurement technique for oscillator crystals.

5 Test methods
5.1 Method A (Fast standard measurement method)
5.1.1 Testing at two drive levels

Testing is performed at low and high drive levels as described in Clause 3 with measurements

of resonance frequency and resistance according to IEC 60444-1. The tolerances are ± 10 %

for the levels of current and ± 20 % for those of power.

a) Storage for at least one day at 105 °C and after that at least 2 hours at room temperature

or, storage for one week at room temperature.

b) The temperature should be kept constant during the measurement (in accordance with

IEC 60444-1 and IEC 60444-5).
= f R = R .
c) Measurement at low drive level (10 µA): f
r r1 r 11
d) Measurement at high drive level (1 mA): f = f R = R .
r r2 r 12
e) Measurement at low drive level (10 µA): f = f , R = R .
r r3 r 13

f) Calculation of γ = R /R . The value of γ shall be smaller than the maximum value of γ

12 11 12 12
given by the line drawn in Figure 1 (abscissa = R ).
g) The tolerable frequency change f − f  shall be 5 × 10 × f unless otherwise
r2 r1 r1
specified in the detail specification.

h) Calculation of γ = R /R . The value of γ shall be smaller than (γ + 1)/2, where the

13 11 13 13
value of γ is taken from Figure 1(abscissa = R ).

i) The tolerable frequency change f − f shall be 2,5 × 10 × f , unless otherwise

r3 r1 r1
specified in the detail specification.

j) The resistance value shall not exceed the maximum value given by the detail specification

at any drive levels.
5.1.2 Testing according to specification

Testing is performed at low to high drive levels and back again to low level as described

in 5.1.1. These and, if necessary, further levels with their tolerances, the permissible

deviations of the frequency and resistance as well as storage conditions shall be specified in

the detail specification.

NOTE 1 The given γ-curve was verified by results obtained over many years of experience with crystal units for

many oscillator types. In most cases, there will be no trouble in start-up, but in critical oscillator configurations,

problems may occur. As it is not possible to manufacture crystal units, which have a constant resistance at any

drive level, the proposed ϒ-curve gives tolerable relations.

Definition of drive level values can be agreed between manufacturer and customer.

---------------------- Page: 10 ----------------------
60444-6  IEC:2013 – 9 –

Use the nominal drive level of the detail specification as value for the high drive level. For

measurement at very high drive levels an additional amplifier may be required.
2,4
1,7
2,2
1,6
1,5
2,0
1,4
1,8
1,3
1,6
1,4 1,2
1,2 1,1
1,0
1,0
1 2 3 5 8 10 20 30 50 80 100 200 300 500
Resistance R (Ω)
IEC 1484/13
Figure 1 – Maximum tolerable resistance ratio γ for the drive
level dependence as a function of the resistances R or R
r2 r3

NOTE 2 The equation for the recommended drive level (if not otherwise specified in the data sheet) is as follows.

Details can be found in Annex A of IEC 60122-2-1:1991, Amendment 1:1993.
I = K ⋅
where,
I is the recommended current for oscillating state;
n is the overtone, fundamental vibration mode, n = 1;
A is the electrode size in mm ;
f is the frequency in MHz;
-2 -1/2
K is 0,35 mA ⋅ mm ⋅ S .
5.2 Method B (Multi-level reference measurement method)

Testing is performed at low and high drive levels as described in Clause 3 with measurements

of resonance frequency and resistance according to IEC 60444-5. The tolerances are ±10 %

for the levels of current and ±20 % for those of power.

a) Storage for at least one day at 105 °C and after that at least 2 hours at room temperature

or storage for one week at room temperature.

NOTE If considered as necessary, the customer and the maker agree on a higher temperature and a longer

duration for the storage before DLD measurement.

b) The temperature should be kept constant during the measurement IAW (in accordance

with IEC 60444-5).

c) The drive level is applied by two types of measurement units. It should also be applied

sequentially starting from the lowest to the highest value and then back to the lowest

value. A definition for the unit of drive levels shall be specified between the crystal

manufacturer and the user.
Resistance ratio γ
(γ + 1)/2
---------------------- Page: 11 ----------------------
– 10 – 60444-6  IEC:2013
1) When the unit of a drive level is mA;

Measurement drives level: from 2 µA to nominal drive level in at least 7 levels which

are logarithmically scaled. (Refer to the equation given under line item f)).
2) When the unit of a drive level is µW;

Measurement drives level: From 2 nW to nominal drive level in at least 7 levels which

are logarithmically scaled. (Refer to the equation given under line item f)).

d) The maximum frequency excursion over all drive levels shall be less than following

specifications.
f (i) − f (i)
s ,max s ,min -6
< 5 × 10
(1)
NOM
or,
f (i) − f (i)
s ,max s ,min
< 0,5 × f
(2)
ADJ
NOM
where

f (i) is the maximum value for frequency measurement values with i = 1 to 2⋅N-1 drive levels;

s ,max

f (i) is the minimum value for frequency measurement values with i = 1 to 2⋅N-1 drive levels;

s ,min
f is the nominal frequency;
NOM
f is the practical specification for frequency adjustment tolerance.
ADJ

e) The maximum ratio of resistance change and the maximum resistance over drive levels

shall be as following specifications.
R (i)
1 ,max
< γ
(1)
R (i)
1 ,min
and
R (1) (γ +1)
(2) <
R (2 ⋅ N −1) 2
and
(3) R (i) < R
1 ,max 1,max
where,

R (i) is the maximum value for resistance measurement values with i = 1 to 2⋅N-1 drive levels;

1 ,max

R (i) is the minimum value for resistance measurement values with i = 1 to 2⋅N-1 drive levels;

1 ,min
R is the maximum resistance, specified by the detail specification.
1,max
γ is the resistance ratio.

f) The N drive levels should be logarithmically scaled, i.e. DL = DL × K. The equation for

N+1 N

the recommended drive level (if not otherwise specified in the data sheet) is as follows.

 
DL N −1
max
 
K =
 
 min 

g) A larger number of drive levels may be necessary in special applications, e.g. those

caused by mechanical coupling with nonlinear spurious resonances (dips) and for failure

analysis.
---------------------- Page: 12 ----------------------
60444-6  IEC:2013 – 11 –
Annex A
(normative)
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.