1、t EIA 448-LB 93 W 3234600 0505466 061 w Reproduced y GLOBAL ENGINEERING DOCUMENTS W Thr Pmnissbn d EIA ihdw Rgalty Apemcn ANSI/ EIA-448-18-1992 APPROVED: June 10, 1992 EIA STANDARD Method 15 Standard Test Method for Electromechanical Switches (Test for Contact Bounce) EU-448-1B (Revision B of Addend
2、um No. 1 to EIA-448) MARC11 1993 ELECTRONIC INDUSTRIES ASSOCIATION ENGINEERING DEPARTMENT EIA 448-LB 73 3234600 05054b7 TT8 NOTICE ?IA Engineering Standards and Publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilita
3、ting interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards and Publications shall not in any respect preclude any member or nonmember of EIA from manufacturing
4、or selling products not conforming to such Standards and Publications, nor shall the existence of such Standards and Publications preclude their voluntary use by those other than EIA members, whether the standard is to be used either domestically or internationally. Recommended Standards and Publica
5、tions are adopted by EIA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, EIA does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Recommended Standard or Publication. This EIA Standard
6、 is considered to have International Standardization implication, but the International Electrotechnical Commission activity has not progressed to the point where a valid comparison between the EIA Standard and the IEC document can be made. This Standard does not purport to address all safety proble
7、ms associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. Published by * ELECTRONIC INDUSTRIES ASSOCIATI
8、ON 1993 Engineering Department 2001 Pennsylvania Ave. N.W., Washington, D.C. 20006 PRICE: Please refer to the current Catalog of EIA & JEDEC STANDARDS & ENGINEERING PUBLICATIONS or call Global Engineering Documents, USA and Canada (1-800-854-7179) International (303-792-21 81) All rights reserved Pr
9、inted in U.S.A. . EIA 448-LB 93 3234600 0.505468 934 This document is copyrighted by the EL4 and may not be reproduced without Organizations may obtain permission to reproduce a limited through entering into a license agreement with the EM. ELA Engineering Publications Office 2001 Pennsylvania Ave.,
10、 N.W. Washington, D.C. 20006 (202)457-4963 1. PURPOSE EIA 448-1B 93 W 3234600 050.5469 870 W EIA-448-1 B Page 1 METHOD 15 CONTACT BOUNCE (From IA Standards Proposal No. 1832, formulated under the cognizance of the EIA P-13.3 Subcommittee on Sensitive, Pushbutton and Keyboard Switches.) NOTE: This St
11、andard is Revision B of Addendum No. 1 to ElA-448, “Standard Test Methods for Electromechanical Switches.“ The purpose of this test method is to determine the duration of contact bounce SO that it can be anticipated and provided for in user circuits. This phenomenon is defined as the random opening
12、and closing of a switch contact that occurs after contact transfer caused by the switch mechanism. It is measured from the moment of first closure (or opening) to the moment when the contacts reach a useful state of equilibrium. Logic circuits are particularly sensitive to the kinetic behavior of sw
13、itching contacts. Unless designed appropriately, these circuits can be triggered to produce spurious data as a result of contact bounce. 2. PROCEDURE 2.1 The switch shall be mounted by its normal mounting means to a structure of sufficient mass that it be considered resonance-free. 2.2 The test circ
14、uit shown in Figure 1, or an equivalent, shall be used for measuring contact bounce. Voltage and current values shall be as specified in the Detail Specification, but shall not exceed an open circuit voltage of 6 Vdc and test current of 100 mA f 5%. 2.3 The detection and display means (oscilloscope
15、or equivalent) utilized in the circuit shall have bandwidth of 1 megahertz or greater, a minimum time base accuracy of 2 5% and shall be capable of showing the quiescent contact state prior to contact opening or closing. EIA 448-LB 93 m 3234600 0505470 592 m EIA-448-1 B Page 2 2.4 The switch mechani
16、sm that causes contact transfer shall be actuated at a velocity as follows, unless otherwise specified in the Detail Specification: (a) Sensitive Switches 25 mm/s Max. (1.0 in/s Max.) (b) Nonsensitive Pushbutton 76 to 127 mm/s Switches (3 to 5 in/s) (c) Key Switches 381 f 254 mm/s (15k 10 in/s) (d)
17、Rotary and Thumbwheel Switches 2 f 1 rad/s (e) Toggle and Rocker Switches 76 to 127 mm/s (3 to 5 in/s) 2.5 When contact bounce is affected by actuation force, the limits of force shall be specified in the Detail Specification. 2.6 The specified contact bounce duration shall be the maximum measuremen
18、t occurring in five consecutive readings of switch closures or switch openings. Contact bounce at switch closure is defined as the interval between switch actuation and switch closure (see Figure 2). Switch actuation occurs when measured voltage is 90% of the open circuits voltage. Switch closure oc
19、curs when the measured voltage remains less than 10% of the open circuit voltage. Contact bounce at switch opening is defined as the interval between switch deactuation and completion of switch opening (see Figure 2). Switch deactuation occurs when the measured voltage is 10% of the open circuit vol
20、tage. Switch opening is completed when the measured voltage remains greater than 90% of the open circuit voltage. Voltage variations occur:ing after completion of switch closure or before switch opening are caused by variations in dynsmic contact resistance. An example of a typical recording of cont
21、act bounce is shown in Figure 2. EIA 448-LB 93 m 3234600 0505471 429 m EIA-448-1 B Page 3 3. SUMMARY The following details shall be specified in the Detail Specifications: 3.1 The test circuit if other than as specified in 2.2. 3.2 The test load if other than as specified in 2.2. 3.3 Actuation rate
22、if other than as specified in 2.4. 3.4 Actuation force when applicable. 3.5 Maximum allowable contact bounce duration at contact opening or closing or both opening and closing. EIA-448-1B . Page 4 EIA YYB-LB 93 W 3234b00 0505Y72 3b5 W RESISTOR POWER SOURCE o I DETECTION ANO DISPLAY MEANS TEST $7 SWITCH FIGURE I CONTACT BOUNCE TEST CIRCUIT OPEN CIRCUIT VOLTAGE 1- FFECTS OF DYNAMIC CONTACT RESISTANCE. CONTACT BOUNCE -L, - - - 90% SWITCH CLOSURE SWITCH IO% -II c- FIGURE 2 TYPICAL CONTACT BOUNCE TRACE OPENING
