EN IEC 60539-1:2023/prA1:2026

SLOVENSKI STANDARD
01-maj-2026
Neposredno ogrevani termistorji z negativnim temperaturnim koeficientom - 1. del:
Splošna specifikacija - Dopolnilo A1
Amendment 1 - Directly heated negative temperature coefficient thermistors - Part 1:
Generic specification
Direkt geheizte temperaturabhängige Widerstände mit negativem
Temperaturkoeffizienten - Teil 1: Fachgrundspezifikation
Thermistances à coefficient de température négatif à chauffage direct - Partie 1:
Spécification générique
Ta slovenski standard je istoveten z: EN IEC 60539-1:2023/prA1:2026
ICS:
31.040.30 Termistorji Thermistors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

40/3280/CDV
COMMITTEE DRAFT FOR VOTE (CDV)

PROJECT NUMBER:
IEC 60539-1/AMD1 ED4
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-03-06 2026-05-29
SUPERSEDES DOCUMENTS:
40/3257/CD, 40/3276/CC
IEC TC 40 : CAPACITORS AND RESISTORS FOR ELECTRONIC EQUIPMENT
SECRETARIAT: SECRETARY:
Netherlands Mr Ronald Drenthen
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):

ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which t hey
are aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries” clau ses
to be included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for submitting ISC
clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Amendment 1 - Directly heated negative temperature coefficient thermistors - Part 1: Generic specification

PROPOSED STABILITY DATE: 2030
NOTE FROM TC/SC OFFICERS:
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IEC CDV 60539-1 ED4.1 AMD1 © IEC 2026

1 INTERNATIONAL ELECTROTECHNICAL COMMISSION
2 ____________
4 DIRECTLY HEATED NEGATIVE TEMPERATURE
5 COEFFICIENT THERMISTORS – Part 1: Generic specification
7 AMENDMENT 1
9 FOREWORD
10 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national
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17 for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
18 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of
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33 reliance upon, this IEC Publication or any other IEC Publications.
34 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for
35 the correct application of this publication.
36 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
37 not be held responsible for identifying any or all such patent rights.
39 This amendment to IEC 60539-1 has been prepared by IEC technical committee 40: Capacitors and
40 resistors for electronic equipment.
41 The text of this Amendment is based on the following documents:
Draft Report on voting
XX/XX/FDIS XX/XX/RVD
43 Full information on the voting for its approval can be found in the report on voting indicated in the above
44 table.
45 The language used for the development of this International Standard is English.
IEC CDV 60539-1 ED4.1 AMD1 © IEC 2026

46 This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in accordance
47 with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available at
48 www.iec.ch/members_experts/refdocs. The main document types developed by IEC are described in
49 greater detail at www.iec.ch/publications.
50 The committee has decided that the contents of this document will remain unchanged until the stability
51 date indicated on the IEC website under webstore.iec.ch in the data related to the specific document. At
52 this date, the document will be
53 • reconfirmed,
54 • withdrawn,
55 • replaced by a revised edition, or
56 • amended.
IEC CDV 60539-1 ED4.1 AMD1 © IEC 2026

60 DIRECTLY HEATED NEGATIVE TEMPERATURE
61 COEFFICIENT THERMISTORS – Part 1: Generic specification
63 AMENDMENT 1
67 3.36 thermal time constant by cooling after self-heating
69 Change in the first paragraph sentence to be
71 time required for a thermistor to cool by 63,2 % of its temperature excess induced by self-heating, in a
72 defined medium when the current passing through an NTC thermistor in a specified medium is
73 suddenly changed from a non-zero load state to a zero load state.
75 5.4.3 Mounting on board /  5.4.3.2 Wave soldering method
77 Change the sentence in 5.4.3.2 a), first line, to be
79 The solder used shall be silver bearing (1.8 to 2.2 %) eutectic Sn/Pb solder together with non-activated
80 flux,…
82 6.8.2 Initial measurement
84 Replace the formula with this formula
86 T = T – (T – T ) × 0.632
i b b a
88 8.1 Rapid change of temperature
90 Change the sentence and item number to be
92 8.1.1 General
IEC CDV 60539-1 ED4.1 AMD1 © IEC 2026

93 The method of test shall be conducted as specified in 8.1.2 to 8.1.6.
94 ----------------------------------------------------------------------------------------------------
95 8.1.4 Intermediate measurement
96 If an intermediate measurement is to be carried out, the load shall be removed and the NTC
97 thermistors allowed to recover under standard atmospheric conditions of testing for not less than 1
98 h and not more than 2 h.
99 The appropriate parameter(s) given in the detail specification shall then be measured using
100 the method specified. The change compared with the value(s) measured in 8.1.2 shall not
101 exceed the limit specified in the relevant detail specification.
102 After intermediate measurements, the thermistors shall be returned to the conditions of
103 test. The interval between the removal from, and the return to the conditions of test for any
104 NTC thermistor shall not exceed 12 h.
105 8.1.5 Recovery
106 After completion of the test, the thermistors shall be removed and allowed to recover under
107 standard atmospheric conditions for a period of 1 h to 2 h.
109 8.1.6 Final inspection, measurements and requirements.
112 8.2 Thermal shock
...