lx5115a Microsemi Corporation, lx5115a Datasheet - Page 4

• Manufacturer Part Number: lx5115a
• Description: Ultra 9 - Channel Scsi Terminator
• Manufacturer: Microsemi Corporation

LX5115A
4
Cable transmission theory suggests to optimize signal speed
and quality, the termination should act both as an ideal voltage
reference when the line is released (deasserted) and as an
ideal current source when the line is active (asserted). Common
active terminators, which consist of
Linear Regulators in series with resis-
tors (typically 110Ω), are a compro-
mise. As the line voltage increases,
the amount of current decreases lin-
early by the equation V = I * R. The
LX5115A, with its unique new archi-
tecture applies the maximum amount
of current regardless of line voltage
until the termination high threshold
(2.85V) is reached.
reproduces the optimum case when the device is enabled.
To enable the device the Disable Pin must be pulled Logic
High or left open. During this mode of operation, quiescent
current is 5.5mA and the device will respond to line demands
Acting as a near ideal line terminator, the LX5115A closely
DISABLE
PIN
2.0V
TERM POWER
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.
P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7
U L T R A 9 - C
P
R O D U C T I O N
F U N C T I O N A L D E S C R I P T I O N
LX5115A
Disable
UltraMAX is a trademark of Linfinity Microelectronics Inc.
Open
H
L
B L O C K D I A G R A M
H A N N E L
CURRENT
BIASING
CIRCUIT
Outputs
Enabled
Enabled
HI Z
S C S I T
D
by delivering 24mA on assertion and by imposing 2.85V on
deassertion. In order to disable the device, the Disable pin
must be driven logic Low. This mode of operation places
the device in a sleep state where a meager 200µA of quiescent
LX5115A has been optimized to have only 3pF of capacitance
per output in the sleep state.
active negation drivers. The device handles up to 7mA of sink
current for drivers which exceed the 2.85V output high.
A T A
An additional feature of the LX5115A is its compatibility with
Quiescent
Current
E R M I N A T O R
5.5mA
200µA
5.5mA
S
H E E T
LIMITING CIRCUIT
24mA CURRENT
2.85V
current is consumed. Additionally, all
outputs are in a Hi-Z (impedance)
state. Sleep mode can be used for
power conservation or to completely
eliminate the terminator from the SCSI
chain. In the second case, termination
node capacitance is important to
consider. The terminator will appear
as a parasitic distributed capacitance
on the line, which can detract from bus
performance.
1 OF 9 CHANNELS
For this reason, the
DATA OUTPUT
PIN DB(0)
UltraMAX