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
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
35Ω (max)
Crystal Cut
AT
Table 5. Recommended Crystal Manufacturers for DS2151 and DS2153
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.
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f = + 175 to + 250ppm