
9-L
INE
LVD SCSI T
ERMINATOR
LX5248/LX5249
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
5
Copyright 2001
Rev. 0.
6
1/0
1
P
R E L I M I N A R Y
D
A T A
S
H E E T
UltraMAX
FUNCTIONAL PIN DESCRIPTION
1-, 2-, 3-, 4-, 5-, 6-, 8-, 8-, 9-/
Negative signal termination lines.
1+, 2+, 3+, 4+, 5+, 6+, 7+, 8+, 9+/ Positive signal termination lines.
V
TERM
Power supply pin for terminator. Connect to SCSI bus TERMPWR. Must be decoupled by one 4.7μF
low-ESR capacitor for every three terminator devices. It is absolutely necessary to connect this pin to
the decoupling capacitor through a very low impedence (big traces on PCB). Keeping distances
very short from the decoupling capacitors to the V
pin is also critical. The value of the
decoupling capacitor is somewhat layout dependant and some applications may benefit from high-
frequency decoupling with 0.1μF capacitors right at V
TERM
pin.
Enables / disables terminator. See Power Down Function Table for logic level per device.
DISCONNECT/
GND/
Terminator ground pin. Connect to ground.
MASTER / SLAVE/
Sometimes referred to as M/S pin in this data sheet. Used to select which terminator is the control-
ling device. MASTER/SLAVE 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
MASTER/SLAVE pin. Please see DIFFSENSE and MASTER/SLAVE Function Tables. Internally
connected to DIFFB pin through 20kOhm resistor.
DIFFB/
Internally connected to DIFFSENSE pin through 20kOhm resistor. It can be used as a mode sense
pin when the device is a non-controlling terminator (MASTER/SLAVE pin is Low). An RC filter
(20kOhm / 0.1μF) is not required on the LX5249, 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 groung connection. It is recommended that these pins be connected to ground,
but can be left floating.
Pin
Designator
Description