T8207-BAL-DT Agere Systems, Inc., T8207-BAL-DT Datasheet - Page 143

• Manufacturer Part Number: T8207-BAL-DT
• Description: CelXpres ATM interconnect. Dry-bagget, tape & reel .
• Manufacturer: Agere Systems, Inc.

Advance Data Sheet
September 2001
Agere Systems Inc.
18 Electrical Requirements and Characteristics
18.1 Crystal Information
The CelXpres T8207 device requires a crystal or external clock source. The crystal may have a frequency from
5 MHz to 40 MHz and is connected between xtalin and xtalout. External 5% capacitors must be connected from
xtalin and xtalout to V
crystal specification requirements shown below.
Table 130. Crystal Specifications
The xtalin input may be driven by an external clock instead of a crystal. The frequency of the external source may
be 5 MHz to 50 MHz. The external clock must meet the requirements shown below.
Table 131. External Clock Requirements
The frequency of the T8207’s main clock (mclk) is derived from the clock at the xtalin input (pclk). See Section 5,
PLL Configuration, for more information on these clocks.
Frequency
Oscillation Mode
Effective Series Resistance
Frequency Tolerance and Stability
Frequency
Maximum Rise or Fall Time
Duty Cycle
C
1
XTALIN
Parameter
Parameter
Figure 19. Crystal
SS
. The value of the external capacitors is determined from the crystal data sheet using the
CRYSTAL
XTALOUT
5 MHz
40%
Min
5 MHz to 40 MHz
Fundamental parallel resonant
See Figure 20 below
5%
—
C
2
50 MHz
Value
Max
60%
5 ns
−1000
−200
−400
−600
−800
Figure 20. Negative Resistance Plot
0
0
10
FREQUENCY (MHZ)
FREQUENCY (MHz)
20
50p
50 pF
= C1
= C2
30
20p
20 pF
= C1
= C2
ATM Interconnect
CelXpres T8207
40
10p
10 pF
= C1
= C2
50
60
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