Seagate ST39205LW/LC ユーザーズマニュアル
70
Cheetah 36XL Product Manual, Rev. E
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 24.
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:
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 25.
Typical SE-LVD alternative transmitter receiver circuits
V1
–SIGNAL
100
Ω
V2
+SIGNAL
MEASURED
PARAMETER
PARAMETER
STEADY STATE
LOGIC INPUT
(1 OR 0)
LOGIC INPUT
(1 OR 0)
DEVICE CONNECTOR
100
Ω
75
Ω
Vs
D
VCCA
VCCB
Single
Ended
Circuitry
Ended
Circuitry
Single
Ended
Receiver
Ended
Receiver
Single
Ended
Negation
Driver
Ended
Negation
Driver
Single
Ended
Assertion
Driver
Ended
Assertion
Driver
Single
Ended
Ground
Driver
Ended
Ground
Driver
Single Ended:
LVD:
LVD:
LVD Signal Drivers
LVD Signal Drivers
LVD
Receiver
Ground
GND
+Signal
–Signal
–Signal
–Signal