PACSZ1284 Datasheet, PDF (4/7 Pages) California Micro Devices Corp – P/ACTIVE IEEE 1284 ECP/EPP TERMINATION NETWORK

PACSZ1284
Performance Information
Filter Capacitors
The IEEE 1284 specification requires both termination
and EMI filtering on a total of 17 lines. Basic filtering is
provided through the presence of a capacitor on all sig-
nal lines. The filter capacitor is the junction capacitance
of an ESD diode. The typical capacitance at a reverse
voltage of 2.5V is 150pF. This diode capacitance is
somewhat voltage dependent. See Figure 1.
Filter Insertion Loss
Figure 2 shows the typical Insertion Loss graphs of the
PACSZ1284 for Data and Strobe signals. The curves
are dependent on the physical location of the filter ele-
ments with respect to the ground terminal of this
device. These graphs are measured in a 50Ω environ-
ment on a Hewlett Packard HP 8753C Analyzer. The
signal source is introduced at the resistor input and the
output is measured at the corresponding protection
diode. The actual pins measured are labeled in the
Figure 2 graph.
Figure 1. Diode Capacitance vs. Reverse Voltage
The higher speed Data and Strobe lines (9 in total)
require an additional series resistor termination for
proper operation, while the eight (8) Status lines do
not. See Table 1 on page 5.
Frequency (MHz)
Figure 2. Typical Filter Insertion Loss
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09/15/03