Seagate Barracuda ST318418N - Manual (Page 79)

Barracuda 36ES2 Product Manual, Rev. B 69
Output characteristics
Each signal (V
s
) driven by LVD interface drivers shall have the following output characteristics when measured
at the disc drive connector:
Steady state Low level output voltage* = –.95 V = < V
s
= < –1.55 V (signal negation/logic 0)
Steady state High level output voltage* = –.95 V = < V
s
= < 1.55 V (signal assertion/logic 1)
Differential voltage = +0.6 V minimum with common-mode voltage ranges 0.700 V = < V
cm
= < 1.800 V.
*These voltages shall be measured between the output terminal and the SCSI device’s logic ground reference.
The output characteristics shall additionally conform to EIA RS-485.
Figure 22. LVD output signals
Input characteristics
Each signal (Vs) received by LVD interface receiver circuits shall have the following input characteristics when
measured at the disk drive connector:
Steady state Low level output voltage* = 0.030 V = < V
s
= < 3.6 V (signal negation/logic 0)
Steady state High level output voltage* = –3.6 V = < V
s
= < –0.030 V (signal assertion/logic 1)
Differential voltage = +0.30 V minimum with common-mode voltage ranges 0.700 V = < V
cm
= < 1.800 V.
(X3T10/1302D)
*These voltages shall be measured between the output terminal and the SCSI device’s logic ground reference.
Input characteristics shall additionally conform to EIA RS-485-983.
Figure 23. Typical SE-LVD alternative transmitter receiver circuits
V1
ÐSIGNAL
100½
V2
+SIGNAL
MEASURED
PARAMETER
STEADY STATE
LOGIC INPUT
(1 OR 0)
DEVICE CONNECTOR
100½
75½ Vs
D
VCCA VCCB
Single
Ended
Circuitry
Single
Ended
Receiver
Single
Ended
Negation
Driver
Single
Ended
Assertion
Driver
Single
Ended
Ground
Driver
Single Ended:
LVD:
LVD Signal Drivers
LVD Signal Drivers
LVD
Receiver
Ground
GND
+Signal
ÐSignal
ÐSignal