LX5121 View Datasheet(PDF) - Microsemi Corporation
Part Name
Description
Manufacturer
LX5121 Datasheet PDF : 4 Pages
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UltraMAX
VCC VCC
DISC1
DISC2
PRODUCT DATABOOK 1996/1997
ULTRA 27-LINE, PLUG AND PLAY SCSI TERMINATOR
PR O D U C T I O N D ATA S H E E T
TERM POWER
BLOCK DIAGRAM
CURRENT
BIASING
CIRCUIT
24mA CURRENT
LIMITING CIRCUIT
2.85V
LX5121
DATA OUTPUT
PIN DB(0)
1.4V
1 OF 27 CHANNELS
FUNCTIONAL DESCRIPTION
Cable transmission
theory suggests that in
POWER UP / POWER DOWN FUNCTION TABLE
reproduces the opti-
mum case when the
order to optimize sig- DISC1 DISC2 W1 W2 N1 T1-T18 T19-T27 device is enabled. To
nal speed and quality,
the termination
H
should act both as an
L
enable the device the
L
DC
DC
DC Enabled Disabled DISC1 and DISC2 pins
H
DC DC DC Disabled Enabled must be driven per the
ideal voltage refer-
L
L
DC DC DC Disabled Disabled above table. During
ence when the line is
H
released (de-asserted)
and as an ideal current
H
source when the line
H
is active (asserted).
H
H
H
H
H
Enabled Enabled this mode of operation,
H
H
H
L
Enabled
Enabled
quiescent current is
12mA and the device
H
H
L
H
Enabled Enabled will respond to line de-
H
H
L
L Disabled Enabled mands by delivering
Common active termi-
H
H
L
H
H Enabled Enabled 24mA on assertion and
nators, which consist
H
of Linear Regulators in
H
series with resistors
(typically 110Ω), are a
H
H
L
H
L
Disabled Enabled by imposing 2.85V on
H
L
L
H
Disabled Disabled de-assertion. Disable
H
L
L
L
Disabled
Disabled
mode places the device
in a sleep state, where
compromise. As the
a meager 150µA of qui-
line voltage increases, the amount of current decreases linearly escent current is consumed. Additionally, all outputs are in
by the equation V = I * R. The UltraMAX LX5121, with its a Hi-Z (impedance) state. Sleep mode can be used for power
unique new architecture, applies the maximum amount of conservation or to completely eliminate the terminator from
current regardless of line voltage until the termination high the SCSI chain.
threshold (2.85V) is reached.
An additional feature of the LX5121 is its compatibility with
Acting as a near ideal line terminator, the LX5121 closely active negation drivers.
Copyright © 1999
Rev. 1.0 5/99
3
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