PRODUCT DATABOOK 1996/1997
LX5111/5112
U LT R A 9 - C
HANNEL
S C S I T
E R M I N ATOR
P
R O D U C T I O N
UltraMAX
D
A T A
S
H E E T
BLOCK DIAGRAM
TERM POWER
THERMAL
LIMITING
CIRCUIT
CURRENT
BIASING
CIRCUIT
24mA CURRENT
LIMITING CIRCUIT
DATA OUTPUT
PIN DB(0)
2.85V
DISCONNECT (5111)
DISCONNECT (5112)
1.4V
1 OF 9 CHANNELS
FUNCTIONAL DESCRIPTION
Cable transmission theory suggests to optimize signal speed
2.85V on deassertion. In order to disable the device, the
and quality, the termination should act both as an ideal voltage
DISCONNECT pin (DISCONNECT pin for the LX5112) must be
reference when the line is released (deasserted) and as an ideal
driven logic
Low
(logic
High
for the LX5112). This mode of
current source when the line is active (asserted). Common
operation places the devices in a sleep state where a meager
active terminators, which consist of Linear Regulators in series
275µA of quiescent current is consumed. Additionally, all outputs
with resistors (typically 110Ω), are
are in a Hi-Z (impedance) state.
P
OWER
U
P
/ P
OWER
D
OWN
F
UNCTION
T
ABLE
a compromise. As the line voltage
Sleep mode can be used for power
increases, the amount of current
LX5111
LX5112
Quiescent
conservation or to completely elimi-
Outputs
decreases linearly by the equation
nate the terminator from the SCSI
DISCONNECT DISCONNECT
Current
V = I * R. The LX5111/5112, with
chain. In the second case, termi-
their unique new architecture ap-
nation node capacitance is impor-
H
L
Enabled
6mA
plies the maximum amount of
tant to consider. The terminators
L
H
HI Z
275µA
current regardless of line voltage
will appear as a parasitic distributed
Open
Open
HI Z
275µA
until the termination high threshold
capacitance on the line, which can
(2.85V) is reached.
detract from bus performance. For
Acting as a near ideal line terminators, the LX5111/5112
this reason, the LX5111/5112 have been optimized to have only
closely reproduce the optimum case when the devices are
3pF of capacitance per output in the sleep state.
enabled. To enable the device the DISCONNECT pin
An additional feature of the LX5111/5112 IC's are their
(DISCONNECT pin for the LX5112) must be pulled logic
High
compatibility with active negation drivers. These devices handle
(logic
Low
for the LX5112). During this mode of operation,
up to 60mA of sink current for drivers which exceed the 2.85V
quiescent current is 6mA and the devices will respond to line
output high.
demands by delivering 24mA on assertion, and by imposing
UltraMAX is a trademark of Linfinity Microelectronics Inc.
PRODUCTION DATA - Information contained in this document is proprietary to Linfinity, and is current as of publication date. This document
may not be modified in any way without the express written consent of Linfinity. Product processing does not necessarily include testing of
all parameters. Linfinity reserves the right to change the configuration and performance of the product and to discontinue product at any time.
4
Copyright © 1997
Rev. 1.1 12/97
MICROSEMI [ MICROSEMI CORPORATION ]
