Abstract: Application Note 325 is a Crystal Selection Guide for these Dallas Single Chip Transceivers: DS2151, DS2152, DS2153, DS2154, DS21552, DS21554, DS21352, DS21354 and DS2155. Specifications for selecting the appropriate crystal in a T1 or E1 application are given in the following order. Table 1: DS2155, DS21x5y, DS2154, and DS2152 Crystal Specifications Table 2: Recommended Crystal Manufacturers that meet DS2155, DS21x5y, DS2154, and DS2152 Crystal Specifications Table 3: Oscillator Manufacturers Table 4: DS2151 and DS2153 Crystal Specifications Table 5: Recommended Crystal Manufacturers that meet DS2151 and DS2153 Crystal Specifications The DS2152, DS2154, DS21x5y, and DS2155 do not require a crystal for most applications. Typically, a clock derived from the system or supplied by an oscillator drives MCLK. If it is not a 1x clock, then appropriate divider can be used to drive the MCLK. For the DS2155, a 16.384MHz, 8.192MHz, 4.096MHz, 2.048MHz, or 1.544MHz clock must be applied at MCLK. ITU specification G.703 requires an accuracy of ±50ppm for both T1 and E1. TR62411 and ANSI specifications require an accuracy of ±32ppm for T1 interfaces. A prescaler divides the 16MHz, 8MHz, or 4MHz clock down to 2.048MHz. There is an on-board PLL for the jitter attenuator, which converts the 2.048MHz clock to a 1.544MHz rate for T1 applications. In an application that derives all timing from the network (loop timed), a crystal can be connected to MCLK and XTALD as shown in Figure 1. There is no pullability requirement for this crystal. Figure 1. Crystal connection. Specifications for selecting the appropriate crystal in a T1 or E1 application are given in Table 1. A list of crystal manufacturers is in Table 2. Table 5 lists oscillator manufacturers. Table 1. DS2155, DS21x5Y, DS2154 and DS2152 Crystal Specifications Parameter Specification Parallel Resonant Frequency 1.544MHz (T1), 2.048MHz (E1) Mode Fundamental Load Capacitance See Figure 1 Tolerance ±50ppm Crystal Cut AT Table 2. Recommended Crystal Manufacturers for DS2155, DS21x5Y, DS2154, and DS2152 Manufacturer Address Part Saronix 141 Jefferson Drive Menlo Park CA 94025 650-470-7700 or 800-227-8974 Commercial Temp Range (T1, 3.088 MHz) NYP0308-XXGHE(L)* (E1, 4.096 MHz) NYP0409-XXGHE (L)* *Need to use divider for MCLK. Ecliptek 3545 Cadillac Ave. Costa Mesa, CA 92626-1401 714-433-1200 Commercial Temp Range Crystal available for both T1 and E1 mode of operations. Table 3. Recommended Oscillator Manufacturers Manufacturer Address Part Saronix 141 Jefferson Drive Menlo Park, CA 94025-1114 650-470-7700 or 800-227-8974 5V 8-Pin DIP SCS-DS-1046 1.544MHz SCS-DS-1047 2.048MHz 3V 8-Pin DIP SCS-DS-1048 1.544MHz SCS-DS-1049 2.048MHz The DS2151 and DS2153 require a crystal that can be pulled off its center frequency. Table 5 lists manufacturers. The part numbers given are for leaded packages. Surface-mount devices typically do not meet the pullability specification. Some of the following manufacturers may offer surface-mountable packages in which the leads have been preformed (gull-winged) with a clip added to provide a third contact point. Table 4. DS2151 and DS2153 Crystal Specifications Parameter Specification Parallel Resonant Frequency 6.176 (T1), 8.192 (E1) Mode Fundamental Load Capacitance 18pF to 20pF Tolerance ±50ppm Pullability CL = 10pF, f = + 175 to + 250ppm CL = 45pF, f = + 175 to - 250ppm Effective Series Resistance 35 (max) Crystal Cut AT Table 5. Recommended Crystal Manufacturers for DS2151 and DS2153 Manufacturer Address Part M-Tron 100 Douglas Ave. P.O. Box 630 Yankton, SD 57078-0630 605-665-9321 605-665-1709 Commercial Temp Range (T1, 6.176MHz) 4575-032 (E1, 8.192MHz) 4575-031 Industrial Temp Range (T1, 6.176MHz) 4144-002 (E1, 8.192MHz) 4144-001 Note: Do not use MP-1 Prefix Raltron 2315 N.W. 107th Ave. Miami, FL 33172 305-593-6033 FAX: 305-594-3973 Commercial Temp Range (T1, 6.176MHz) A-6.176-18.5-DS (E1, 8.192MHz) A-8.192-18.5-DS Industrial Temp Range (T1, 6.176MHz) A-6.176-18.5-DSE (E1, 8.192MHz) A-8, 192-18.5-DSE Sunny-Emi Co. Suntrac (Dist) 11925 Ventura Blvd. Studio City, CA 91604 818-509-8985 Industrial Temp Range (T1, 6.176MHz) SE 061-32 (E1, 8.192MHz) SE 081-30 JAN 2341 Crystal Dr. P.O. Box 6017 Fort Myers, FL 33906-6017 941-936-2297 FAX: 941-936-3750 Commercial Temp Range (T1, 6.176MHz) JC6B18 (E1, 8.192MHz) JC8B18 Ecliptek 3545 Cadillac Ave. Costa Mesa, CA 92626-1401 714-433-1200 Commercial Temp Range (T1, 6.176MHz) ECX-4173-6.176M (E1, 8.192MHz) ECX-3876-8.192M Saronix Strategic Marketing, Inc. 624 W. University Suite 265 Denton, TX 76201 COMMERCIAL TEMP RANGE (T1, 6.176MHz) SRX5310(L) (E1, 8.192MHz) SRX5469(L) Maxim has qualified a sample of each device from the above manufacturers and has found that the device meets or exceeds our specifications. We do not conduct an ongoing qualification of these manufacturers. 相关型号   APP 325: Jun 20, 2002 DS21352 3.3V DS21352及5V DS21552 T1单芯片收发器 完整的数据资料 (PDF, 1.1MB) 免费样品 DS21354 3.3V/5V、E1单芯片收发器(SCT) 完整的数据资料 (PDF, 960kB) 免费样品 DS2152 增强型T1单芯片收发器 完整的数据资料 (PDF, 1.3MB) 免费样品 DS2154 增强型E1单芯片收发器 完整的数据资料 (PDF, 1MB) 免费样品 DS2155 T1/E1/J1单芯片收发器 完整的数据资料 (PDF, 2.0MB) 免费样品 DS21552 3.3V DS21352及5V DS21552 T1单芯片收发器 完整的数据资料 (PDF, 1.1MB) 免费样品 DS21554 3.3V/5V、E1单芯片收发器(SCT) 完整的数据资料 (PDF, 960kB) 免费样品 自动更新 需要自动接收最新发布的应用笔记吗？请订阅EE-Mail™ (English only)。 我们期待您的反馈！ 喜欢？不喜欢？有待改善？或为我们提供建议？请与我们联系 — 我们将根据您的意见或建议改善我们的工作。 网页评价或提供建议   下载，PDF格式 (29kB)  AN325, AN 325, APP325, Appnote325, Appnote 325