Seagate ST373454FC Cheetah 15K.4 FC Product Manual - Page 84

LED driver signals, Differential PECL output, Differential PECL input

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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 28 for the output characteristics of the LED drive signals. Table 28: LED drive signal State LED off, high LED on, low Current drive available 0 < IOH < 100µA IOL < -30 mA Output voltage 0 < VOL < 0.8V 9.6.3 Differential PECL output The serial PECL output signal voltage characteristics are provided in Table 29. 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 29: Differential PECL output characteristics Description Serial output voltage swing Parameter 600 < Vout < 1300 mV Notes Centered at 1.32V Figure 22 provides the data output valid eye diagram relative to the bit cell time. 941 ps Vout (mv) Figure 22. 800 ps Transmit eye diagram 9.6.4 Differential PECL input The serial PECL input signal voltage characteristics are provided in Table 30. Table 30: Differential PECL input characteristics Description Serial input voltage swing Parameter 200 < Vin < 1.300 mV Notes AC coupled 72 Cheetah 15K.4 FC Product Manual, Rev. C

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72
Cheetah 15K.4 FC Product Manual, Rev. C
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 28 for the output characteristics of the LED drive signals.
9.6.3
Differential PECL output
The serial PECL output signal voltage characteristics are provided in Table 29. 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.
Figure 22 provides the data output valid eye diagram relative to the bit cell time.
Figure 22.
Transmit eye diagram
9.6.4
Differential PECL input
The serial PECL input signal voltage characteristics are provided in Table 30.
Table 28:
LED drive signal
State
Current drive available
Output voltage
LED off, high
0 < I
OH
< 100μA
LED on, low
I
OL
< -30 mA
0 < V
OL
< 0.8V
Table 29:
Differential PECL output characteristics
Description
Parameter
Notes
Serial output voltage swing
600 < V
out
< 1300 mV
Centered at 1.32V
Table 30:
Differential PECL input characteristics
Description
Parameter
Notes
Serial input voltage swing
200 < V
in
< 1.300 mV
AC coupled
941 ps
Vout (mv)
800 ps