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Cheetah 73FC Product Manual, Rev. C
9.6
Signal characteristics
This section describes the electrical signal characteristics of the drive's input and output signals. See Table 19
on page 52 for signal type and signal name information.
9.6.1
TTL input characteristics
Table 24 provides the TTL characteristics.
Table 24:
TTL characteristics
State
Input high
Input low
Output high (-EN Bypass A, B)
Output low (-EN Bypass A, B)
Output high (-Parallel ESI)
Output low (-Parallel ESI)
Output high (all other outputs)
Output low (all other outputs)
9.6.2
LED driver signals
Fault and Active LED signals are located in the FC-SCA connector (J1) and through the indicator connector
(J6). See Table 25 for the output characteristics of the LED drive signals.
Table 25:
LED drive signal
State
Current drive available
LED off, high
0 < I
OH
LED on, low
I
< -30 mA
OL
9.6.3
Differential PECL output
The serial PECL output signal voltage characteristics are provided in Table 26. The outputs are not AC coupled
in order to deliver maximum signal without rise and fall time degradation. You must AC couple the receiver to
isolate potentially different DC characteristics of the outputs and the receiver.
Table 26:
Differential PECL output characteristics
Description
Serial output voltage swing
Voltage
1.9 < V
< 5.5V
IH
-0.5V < V
< 0.9V
IL
2.4 < V
< 5.25V
OH
V
< 0.5V
OL
2.4 < V
< 0.9 V
OH
V
> 0.9V
OH
CC
0 < V
< .45V
OL
2.4 < V
< 0.9 V
OH
V
> 0.9V
OH
CC
0 < V
< .45V
OL
Output voltage
< 100µA
0 < V
Parameter
300 < V
< 650 mV
out
Current
I
= ±500nA max.
IH
I
= ±500nA max.
OL
I
< -3mA
OH
I
< 3mA
OL
I
< -2.4mA
CC
OH
I
< -500µA
OH
I
< 2.4mA
OL
I
< -1.6mA
CC
OH
I
< -500µA
OH
I
< 1.6mA
OL
< 0.8V
OL
57
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