Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
Copyright © 2000
Rev. 1.1, 2006-02-27
WWW.Microsemi .COM
LX5255
9-Line LVD SCSI Terminator
TM
®
FUNCTIONAL PIN DESCRIPTION
PIN NAME DESCRIPTION
1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-
Negative signal termination lines for LVD mode.
1+, 2+, 3+, 4+, 5+, 6+, 7+, 8+, 9+
Positive signal termination lines for LVD mode.
V
TERM
Power supply pin for terminator. Connect to SCSI bus VTERM. Must be
decoupled by one 4.7
µF low-ESR capacitor for every three terminator devices. It is
absolutely necessary to connect this pin to the decoupling capacitor through a very low
impedance (big traces to PCB). Keeping distances very short from the decoupling
capacitors is somewhat layout dependent and some applications may benefit from high
frequency decoupling with 0.1
µF capacitors at V
TERM
pin.
DISC
Enables/Disables terminator. See Power Down Function Table for logic levels.
GND
Terminator ground pin. Connect to ground.
DIFSENS
Differential sense pin connected to system DIFFSENS line. Drives the SCSI bus
DIFSENS line to 1.3V.
DIFFB
Used to detect the SCSI bus mode (SE, LVD or HVD). Should be connected to a 4.7uF
capacitor to GND, and a 50K resistor to the DIFFSENS pin (see Figure 2 on page 5).
5
BLOCK DIAGRAM
DIFSENS
DISC
DIFFB
LATCH
Window
Comp.
+
-
POWER
ON
&
MODE
DELAY
LVD
SE
HVD
150
1.07 mA
1.07 mA
52.5
52.5
VTERM
LVD
GND
LVD(-)
LVD(+)
1 of 9
Lines
10mA
I-Limited
1.3V
Source
HVD
SE
LVD
HVD
SE
24
13
11
10
12
3
2
DISC
1.25V
DISC
Figure 1 – LX5255CPW Block Diagram
P
P
A
A
C
C
K
K
A
A
G
G
E
E
D
D
A
A
T
T
A
A
