LX5111A Просмотр технического описания (PDF) - Microsemi Corporation
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LX5111A Datasheet PDF : 4 Pages
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PRODUCT DATABOOK 1996/1997
LX5111A/5112A
ULTRA 9-CHANNEL SCSI TERMINATOR
PR E L I M I N A RY D ATA S H E E T
TERM POWER
BLOCK DIAGRAM
CURRENT
BIASING
CIRCUIT
24mA CURRENT
LIMITING CIRCUIT
UltraMAX
DATA OUTPUT
PIN DB(0)
DISCONNECT (5111)
DISCONNECT (5112)
1.4V
2.85V
1 OF 9 CHANNELS
FUNCTIONAL DESCRIPTION
Cable transmission theory suggests to optimize signal speed demands by delivering 24mA on assertion, and by imposing
and quality, the termination should act both as an ideal voltage 2.85V on deassertion. In order to disable the device, the
reference when the line is released (deasserted) and as an ideal DISCONNECT pin (DISCONNECT pin for the LX5112A) must
current source when the line is active (asserted). Common be driven logic Low (logic High for the LX5112A). This mode
active terminators, which consist of Linear Regulators in series of operation places the devices in a sleep state where a meager
with resistors (typically 110Ω), are
a compromise. As the line voltage
POWER UP / POWER DOWN FUNCTION TABLE
275µA of quiescent current is con-
sumed. Additionally, all outputs are
increases, the amount of current
decreases linearly by the equation
V = I * R. The LX5111A/5112A, with
LX5111A LX5112A
DISCONNECT DISCONNECT
Outputs
Quiescent
Current
in a Hi-Z (impedance) state. Sleep
mode can be used for power con-
servation or to completely eliminate
their unique new architecture ap-
plies the maximum amount of
current regardless of line voltage
until the termination high threshold
H
L
Open
L
H
Open
Enabled
HI Z
HI Z
6mA
275µA
275µA
the terminator from the SCSI chain.
In the second case, termination
node capacitance is important to
consider. The terminators will ap-
(2.85V) is reached.
pear as a parasitic distributed capaci-
Acting as a near ideal line terminators, the LX5111A/5112A tance on the line, which can detract from bus performance. For
closely reproduce the optimum case when the devices are this reason, the LX5111A/5112A have been optimized to have
enabled. To enable the device the DISCONNECT pin only 3pF of capacitance per output in the sleep state.
(DISCONNECT pin for the LX5112A) must be pulled logic High
An additional feature of the LX5111A/5112A IC's are their
(logic Low for the LX5112A). During this mode of operation, compatibility with active negation drivers.
quiescent current is 6mA and the devices will respond to line
UltraMAX is a trademark of Linfinity Microelectronics Inc.
PRELIMINARY DATA - Information contained in this document is pre-production data, and is proprietary to LinFinity. It may
not modified in any way without the express written consent of LinFinity. Product referred to herein is offered in sample form
only, and Linfinity reserves the right to change or discontinue this proposed product at any time.
4
Copyright © 1999
Rev. 0.1 3/99
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