+/+…when timing is critical
C9815B
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
MIN
NOM
MAX
MIN
2.41
NOM
2.59
MAX
2.79
C
A
A1
A2
B
0.095
0.008
0.088
0.008
0.005
0.720
0.291
0.102
0.110
0.016
0.092
0.0135
0.010
0.730
0.299
L
0.012
0.203 0.305 0.406
H
E
-
2.24
0.203
0.127
-
-
-
2.34
-
0.343
0.254
C
D
E
-
0.725
18.29 18.42 18.54
D
a
0.295
7.39
7.49
7.60
A2
A
e
0.025 BSC
0.635 BSC
H
L
0.395
0.020
0º
-
-
-
0.420
0.040
8º
10.03
0.508
0º
-
-
-
10.67
1.016
8º
A1
e
B
a
INTERNATIONAL MICROCIRCUITS, INC. 525 LOS COCHES ST.,
MILPITAS, CA 95035, USA TEL: 408-263-6300, FAX 408-263-6571
http://www.imicorp.com
Rev 1.1
3/12/2000
Page 17 of 18