Seagate Barracuda 18FC ST118273FC, Product Manual

Page: 62 / 76

52 Barracuda 18FC Product Manual, Rev. B
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.
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.
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 22: TTL characteristics
State Voltage Current
Input high 1.9 < V
IH
< 5.5V 0 < I
IH
< ±500nA max.
Input low -0.5V < V
IL
< 0.9V 0 < I
IL
< ±500nA max.
Output high (-EN Bypass A, B) 2.4 < V
OH
< 5.25V I
OH
< -3mA
Output low (-EN Bypass A, B) V
OL
< 0.5V I
OL
< 3mA
Output high (-Parallel ESI) V
OH
> 2.4V
V
OH
> 0.9V
cc
I
OH
< -2.4mA
I
OH
< -500µA
Output low (-Parallel ESI) 0 < V
OL
< .45V I
OL
< 2.4mA
Output high (all other outputs) V
OH
> 2.4V
V
OH
> 0.9V
cc
I
OH
< -1.6mA
I
OH
< -500µA
Output low (all other outputs) 0 < V
OL
< .45V I
OL
< 1.6mA
Table 23: 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
< 0.4V
Table 24: Differential PECL output characteristics
Description Parameter Notes
Serial output voltage swing 300 < V
out
< 650 mV Centered at 1.32V