Signal Characteristics; Ttl Characteristics; Led Driver Signals; Differential Pecl Output - Seagate ST118273FC Product Manual

Barracuda 18fc disc drive
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52
9.6

Signal characteristics

This section describes the electrical signal characteristics of the drive's input and output signals. See Table 18
on page 48 for signal type and signal name information.
9.6.1

TTL characteristics

Table 22 provides the TTL characteristics.
Table 22:
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 23 for the output characteristics of the LED drive signals.
Table 23:
LED drive signal
State
Current drive available
LED off, high
0 < I
< 100µA
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 24. 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 24:
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
V
> 2.4V
OH
V
> 0.9V
cc
OH
0 < V
< .45V
OL
V
> 2.4V
OH
V
> 0.9V
cc
OH
0 < V
< .45V
OL
Output voltage
0 < V
< 0.4V
OL
Parameter
Notes
300 < V
< 650 mV
Centered at 1.32V
out
Barracuda 18FC Product Manual, Rev. B
Current
0 < I
< ±500nA max.
IH
0 < I
< ±500nA max.
IL
I
< -3mA
OH
I
< 3mA
OL
I
< -2.4mA
OH
I
< -500µA
OH
I
< 2.4mA
OL
I
< -1.6mA
OH
I
< -500µA
OH
I
< 1.6mA
OL

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