2/24/2008 9T6WP
BCM7405
Preliminary Hardware Data Module
Crystal Requirements
06/29/07
Bro a d c o m C o rp o r a ti o n
Page 1-170
Crystal Requirements
Document
7405-1HDM00-R
E
XTERNAL
C
OMPONENTS
An external filter is required for the differential oscillator to operate in its 3
rd
Overtone mode.
The required board components for proper 3
rd
overtone crystal oscillator operation: Inductors - 10% tolerance; Capacitors -
5% tolerance; and Resistors - 1% tolerance.
Figure 1-53: Example: Vendor (TXC) Part Number for 3OT Crystal: 7EA0000023
SATA C
RYSTAL
The following table describes the parameters for the SATA crystal. The SATA crystal is required for the operation of the
SATA core—if this core is not required for a particular application, this crystal does not need to be installed.
Example:
Vendor (Ecliptek) Part Number for SATA crystal: E13C4D1F-100MHz
Table 1-40: SATA Crystal Electrical Characteristics
Parameter
Symbol
Comment
Min.
Typ.
Max.
Unit
Reference frequency
Fref
–
–
100
–
MHz
Tolerance
Tol
T = 25C
-50
–
+50
ppm
Stability over temperature
–
0 to 70 C
-50
–
+50
ppm
Duty cycle
Tduty
–
45
–
55
%
Rise time
Trise
20% to 80%
–
300
600
ps
Fall time
Tfall
20% to 80%
–
300
600
ps
Jitter
Jp-p
Peak to Peak
–
0.7
1
ps
Input low level
Vil
–
1.6
1.45
1.3
V
Input high level
Vih
–
1.9
2.1
2.4
V
Equivalent series resistor
ESR
–
–
–
40
ohm
Drive level
–
–
–
–
1
mW
External Filter
R
E
= 600
L
E
= 2.7
C
E
= 33 pF
DIFFOSC_65LP
XTALP
XTALN
54 MHz
3
rd
OT Crystal
(parallel resonant with 10 pF load
cap, ESR < 40 )
C
L
= 8.2 pF
R
E
C
E
L
E
C
L
= 8.2 pF
22
Ω
Ω
22
Ω
μ
H
