GS2971A Datasheet, PDF (34/152 Pages) Gennum Corporation – Integrated audio clock generator

Alternately, a 27MHz external clock source can be connected to the XTAL1 pin of the
device, as shown in Figure 4-4.
The frequency variation of the crystal including aging, supply and temperature
variation, should be less than +/-100ppm.
The equivalent series resistance (or motional resistance) should be a maximum of 50Ω.
The external crystal is used in the frequency acquisition process. It has no impact on the
output jitter performance of the part when the part is locked to incoming data. Because
of this, the only key parameter is the frequency variation of the crystal that is stated
above.
External Crystal Connection
16pF
K6 _XTAL1
External Clock Source Connection
External
Clock
K6 _XTAL1
16pF
J6 _XTAL2
NC
J6 _XTAL2
Notes:
1. Capacitor values listed represent the total capacitance,
including discrete capacitance and parasitic board capacitance.
2.XTAL1 serves as an input, which may alternatively accept a 27MHz clock
source.
Figure 4-4:27MHz Clock Sources
Table 4-3:Input Clock Requirements
Parameter
Min
Typ
XTAL1 Low Level Input Voltage
−
−
(V_il)
XTAL1 High Level Input
80% of VDDIO
−
Voltage (V_ih)
XTAL1 Input Slew Rate
2
−
XTAL1 to XOUT Prop. Delay
1.3
1.5
(High to Low)
Max
20% of VDD_IO
−
−
2.3
UOM
V
V
V/ns
ns
Notes
3
3
3
3
GS2971A 3Gb/s, HD, SD SDI Receiver
Data Sheet
54311 - 2
September 2012
34 of 152