+/+…when timing is critical
C9815C
Low EMI Clock Generator for Intel 133MHz/2DIMM Chipset Systems
Preliminary
Suggested Oscillator Crystal Parameters (Cont.)
As an example, and using this formula for this datasheet’s device, a design that has no discrete loading capacitors
(CDISC) and each of the crystal to device PCB traces has a capacitance (CPCB) to ground of 4pF (typical value) would
calculate as:
CL = (4pF + 36pF + 0pF) X (4pF + 36pF + 0pF) = 40 X 40
(4pF + 36pF + 0pF) + (4pF + 36pF + 0pF) 40 + 40
= 1600
80
= 20pF
Therefore to obtain output frequencies that are as close to this data sheets specified values as possible, in this design
example, you should specify a parallel cut crystal that is designed to work into a load of 20pF.
Package Drawing and Dimensions
56 Pin SSOP Outline Dimensions
INCHES
MILLIMETERS
SYMBOL
A
MIN
NOM
MAX
MIN
2.41
NOM
2.59
MAX
C
0.095
0.102
0.110
2.79
0.41
2.34
A1
A2
B
0.008
0.088
0.008
0.005
.720
0.012
0.016
0.092
0.0135
0.010
.730
0.20
2.24
0.31
2.29
L
0.090
H
E
0.010
0.203 0.254 0.343
0.127 0.254
18.29 18.42 18.54
C
D
E
-
-
.725
D
0.292
0.296
0.299
7.39
7.49
7.60
a
e
0.025 BSC
0.635 BSC
A2
A
H
L
0.395
0.020
0°
-
-
0.420
0.040
8°
10.03
0.508
0°
-
-
10.67
1.016
8°
A1
e
B
a
5°
5°
INTERNATIONAL MICROCIRCUITS, INC. 525 LOS COCHES ST.,
MILPITAS, CA 95035, USA TEL: 408-263-6300, FAX 408-263-6571
http://www.imicorp.com
Rev 1.2
4/5/2000
Page 17 of 18
CYPRESS [ CYPRESS ]
