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1、,SFF-8431簡介及SFI電氣參數測試,Agenda,Introduction of SFF-8431 SFF-8431 Standard Compliance Test of SFI Eye Diagram Test by DSA8200,Introduction of SFF-8431,BRIEF INTRODUCTION OF SFF-8431 The specification of SFF-8431 defines the electrical interfaces and their test methods between the SFP+ module and host b
2、oard for operation up to 11.1 GBd. The high speed electrical interface between the host and SFP+ module is called “SFI”. SFI simplifies the module and leverages host based transmit pre-emphasis and host based receive equalization to overcome PCB and external media impairments. SFI typically operates
3、 with one connector at the module interface and up to about 200 mm of improved FR4 material or 150 mm of standard FR4. The electrical interface is based on high speed, low voltage AC coupled logic with a nominal differential impedance of 100 . The SFP+ specifications includes management, low speed s
4、ignal, high speed signal, connector (defined by SFF-8083), mechanical (defined by SFF-8432), and appendices providing parameter and test board definitions, and implementation and measurement descriptions.,Introduction of SFF-8431,The SFP+ SUPPORTED STANDARDS,Introduction of SFF-8431,POWER SPECIFICAT
5、IONS OF SFP+,The module signal ground contacts VeeR and VeeT should be isolated from module case.At host power up the host shall supply VccT and VccR to the module within 100 ms of each other. SFP+ low speed signaling is based on Low Voltage TTL (LVTTL) operating with a module supply of 3.3 V +/-5%
6、and with a host supply range of 2.38 to 3.46 V.To avoid exceeding system power supply limits and cooling capacity, all modules at power up by default shall operate with 1.0 W. Hosts supporting Power Level II operation may enable a Power Level II module through the 2-wire interface. Power Level II mo
7、dules shall assert the power level declaration bit of SFF-8472 Over long spans such as the 40km Ethernet extended reach (ER) long wavelength applications, the SFP+ transceivers may require additional power consumption, especially at extreme operating conditions. Power Level I modules Up to 1.0 W Pow
8、er Level II modules Up to 1.5 W,GENERAL REQUIREMENTS,Introduction of SFF-8431,The maximum power level is allowed to exceed the classified power level for 500 ms following hot insertion or power up, or Power Level II authorization, however the current is limited to values given by the following table
9、.,POWER SPECIFICATIONS OF SFP+,Introduction of SFF-8431,The SFP+ module shall meet ESD requirements given in EN61000-4-2, criterion B test specification such that units are subjected to 15 kV air discharges during operation and 8 kV direct contact discharges to the case.,Introduction of SFF-8431,HIG
10、H SPEED ELECTRICAL SPECIFICATIONS of SFI,SFI signaling is based on differential high speed low voltage logic with AC coupling in the module. SFI was developed with the primary goal of low power and low electromagnetic interference (EMI). To satisfy this requirement the nominal differential signal le
11、vels are 500 mV p-p with edge speed control to reduce EMI.,Introduction of SFF-8431,PCB LAYOUT RECOMMENDATIONS,The PCB traces are recommended by the specification to meet 10010 differential impedace with nominal 7% differential coupling. It is preferable to have the impedance tolerance be 5. Route d
12、ifferential pairs at least 8x their trace-width from other traces. Avoid sharp angles in routing, chamfer corners. In order to avoid reflection, the recommended minimum trace length requirement is “1 inch” in FR4. When there must be vias on the high-speed differential signals, the 100 differential v
13、ias is recommended be used. And stubs due to vias must be avoided.,The maximum SFI trace length recommend by the specification of SFF-8431.,SFF-8431 Standard Compliance Test of SFI,TEST ENVIRONMENT REQUIREMENTS The bandwidth of measurement instrument shall be 12 GHz or above; Require AC coupled test
14、 equipment on all test ports； All SFI test equipment must have 50ohm single ended impedance； Reference impedance for differential measurements is 100ohm, and the reference impedance for common mode measurements is 25ohm; Host compliance test board is required.,SFF-8431 STANDARD COMPLIANCE TEST of SF
15、I,TEST METHODOLOGY AND MEASUREMENT HOST COMPLIANCE TEST A.1 Test pointHost system transmitter and receiver compliance are defined by tests in which a Host Compliance Board is inserted in place of the SFP+ module. The compliance points are B.,SFF-8431 Standard Compliance Test of SFI,A.2 Measurement s
16、etup,SFF-8431 Standard Compliance Test of SFI,A.2 TEST EQUIPMENT,SFF-8431 Standard Compliance Test of SFI,A.3 Host Transmitter Output Jitter and Eye Mask Specifications at B,SFF-8431 Standard Compliance Test of SFI,10GSFP+Cu DIRECT ATTACH CABLE Compliance Test,10GSFP+Cu cable assemblies are effectiv
17、ely constructed out of a pair of SFP+ modules with the OE components replaced with copper cabling. The cable assembly shall incorporate DC blocking capacitors with at least 4.3 V rating on the RX side and with high pass pole of between 20 kHz and 100 kHz. The drain wire is connected to VeeT and to VeeR. The cable shield directly connects the module A and B cases.,
