Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
Copyright © 2002
Rev. 1.2b, 2005-08-29
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LX5250/5252
9-Line Multimode 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. Signal termination lines for SE mode.
1+, 2+, 3+, 4+, 5+, 6+, 7+, 8+, 9+
Positive signal termination lines for LVD mode. Psuedo-ground lines for SE 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.
DISCONNECT
Enables/Disables terminator. See Power Down Function Table for logic levels
for LX5250 and LX5252
.
GND
Terminator ground pin. Connect to ground.
MASTER/SLAVE
Sometimes referred to as M/S pin in this datasheet. Used to select which terminator is the
controlling device. M/S pin High or Open enables the DIFFSENSE output drive. Please
see MASTER/SLAVE Function Table.
DIFFSENSE
This is a dual function pin. It drives the SCSI bus DIFFSENS line. It is also the sense pin
to detect the SCSI bus mode (LVD, SE, or HVD). DIFFSENSE output drive can be
disabled with low level on the M/S pin. Please see DIFFSENSE and MASTER/SLAVE
Function Tables. Internally connected to DIFFB pin through a 20K
Ω resistor.
DIFFB
Internally connected to DIFFSENSE pin through a 20K
Ω resistor. It can be used as a
mode sense pin when the device is non-controlling terminator (M/S is low). An RC filter
(50K Ω resistor & 4.7µF) is not required on the LX5250 as it has an internal timer.
SE Single-Ended output; when High, terminator is operating in SE mode.
LVD Low Voltage Differential output; when High, terminator is operating in LVD mode.
HVD High Voltage Differential output; when High, terminator is operating in HVD mode.
HEATSINK
Attached to die mounting pad, but not bonded to GND pin. Pins should be considered a
heat sink only, and not a true ground connection. It is recommended that these pins be
connected to ground, but can be left floating.
P
P
A
A
C
C
K
K
A
A
G
G
E
E
D
D
A
A
T
T
A
A
