BS EN 60512-25-4 pdf free download

BS EN 60512-25-4 pdf free download.Connectors for electronic equipment — Tests and measurements — Part 25-4: Test 25d — Propagation delay.
2.2 Fixture Unless otherwise specified in the reference document, the specimen environment impedance shall match the impedance of the test equipment. Typically, this will be 50 Ω for single-ended measurements and 1 00 Ω for differential. 2.2.1 Method A, single-ended The fixture shall allow one signal line to be driven at a time. The driven line shall be terminated according to one of the methods of figure A.2 with the specimen environment impedance. Unless otherwise specified, a 1 :1 signal-to-ground ratio shall be used with each end having all grounds commoned. Each line adjacent to the driven line(s) shall also be terminated in the specimen environment impedance at both near and far ends. 2.2.1.1 Probe technique The fixture shall be designed to allow the signal to be probed at the two points between which the delay is to be measured; see figure A.1 a. 2.2.1.2 Insertion technique The fixture shall be designed to allow measurement of propagation delay with and without the specimen; see figure A.1 b. 2.2.1.3 Reference fixture technique Two fixtures shall be designed that include the same fixture electrical length and character- istics of environment transmission line. The “specimen fixture” includes the specimen. The “reference fixture” does not include the specimen. The fixture electrical length does not include the specimen length; see figure A.1 c.2.2.2 Method B, differentially driven The fixture shall allow one signal pair to be driven at a time. The driven line shall be terminated according to one of the methods of figure A.3 with the specimen environment impedance. Unless otherwise specified, a 2:1 signal-to-ground ratio shall be used. Each line adjacent to the driven line(s) shall also be terminated in the specimen environment impedance at both near and far ends. 2.2.2.1 Probe technique The fixture shall be designed to allow the signal pair to be probed at the points between which the delay is to be measured; see figure A.1 a. 2.2.2.2 Insertion technique The fixture shall be designed to allow measurement of propagation delay with and without the specimen; see figure A.1 b. 2.2.2.3 Reference fixture technique Two fixtures shall be designed that include the same fixture electrical length and characteristics of the environment transmission line. The “specimen fixture” includes the specimen. The “reference fixture” does not include the specimen. The fixture electrical length does not include the specimen length; see figure A.1 c.4 Test procedure Unless otherwise specified, the measurement system rise time shall be less than or equal to the measured delay. The measurement system rise times specified in table 1 are recom- mended. The three techniques below apply to single-ended and differential measurements. For differential measurements, it is necessary to determine if any phase and/or amplitude errors exist between the probe/channels and to provide necessary compensation for these errors so that each step arrives at the specimen simultaneously. Two measurements shall be performed as described in 4.2 or 4.3 and the time difference recorded; see figure 2 and figure A.1 . Unless otherwise specified, for all three techniques the delay shall be measured at both the 1 0 % and 50 % amplitudes. Place the specimen a minimum of 5 cm from any object that would affect measured results. NOTE 1 The test professional should be aware of limitations of any mathematical operation(s) performed by an instrument (e.g. normalization or software filtering). NOTE 2 Specimen induced skew should not be compensated. When skew is observed, a waveform plot should be provided. NOTE 3 The input and output step amplitudes may not be equal, due to attenuation in the device under test. When this occurs, the output step 1 0 % and 90 % levels are referenced from maximum output voltage, regardless of what voltage was put in. BS EN 60512-25-4 pdf download.