lx5111a Microsemi Corporation, lx5111a Datasheet - Page 4

• Manufacturer Part Number: lx5111a
• Description: Ult Ra 9 - Channel Scsi Terminator
• Manufacturer: Microsemi Corporation

LX5111A/5112A
4
DISCONNECT (5111)
DISCONNECT (5112)
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 resistors (typically 110 ), are
a compromise. As the line voltage
increases, the amount of current
decreases linearly by the equation
V = I * R. The LX5111A/5112A, with
their unique new architecture ap-
plies the maximum amount of
current regardless of line voltage
until the termination high threshold
(2.85V) is reached.
closely reproduce the optimum case when the devices are
enabled.
(DISCONNECT pin for the LX5112A) must be pulled logic High
(logic Low for the LX5112A). During this mode of operation,
quiescent current is 6mA and the devices will respond to line
Acting as a near ideal line terminators, the LX5111A/5112A
To enable the device the DISCONNECT pin
1.4V
TERM POWER
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.
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
DISCONNECT DISCONNECT
P
LX5111A
Open
R E L I M I N A R Y
P
F U N C T I O N A L D E S C R I P T I O N
OWER
H
L
UltraMAX is a trademark of Linfinity Microelectronics Inc.
U
B L O C K D I A G R A M
P
H A N N E L
LX5112A
/ P
Open
H
OWER
L
CURRENT
D
BIASING
CIRCUIT
S C S I T
OWN
D
demands by delivering 24mA on assertion, and by imposing
2.85V on deassertion.
DISCONNECT pin (DISCONNECT pin for the LX5112A) must
be driven logic Low (logic High for the LX5112A). This mode
of operation places the devices in a sleep state where a meager
Outputs
Enabled
tance on the line, which can detract from bus performance. For
this reason, the LX5111A/5112A have been optimized to have
only 3pF of capacitance per output in the sleep state.
compatibility with active negation drivers.
A T A
An additional feature of the LX5111A/5112A IC's are their
HI Z
HI Z
F
UNCTION
E R M I N A T O R
S
Quiescent
H E E T
Current
275µA
275µA
T
6mA
ABLE
LIMITING CIRCUIT
24mA CURRENT
In order to disable the device, the
2.85V
275µA of quiescent current is con-
sumed. Additionally, all outputs are
in a Hi-Z (impedance) state. Sleep
mode can be used for power con-
servation or to completely eliminate
the terminator from the SCSI chain.
In the second case, termination
node capacitance is important to
consider. The terminators will ap-
pear as a parasitic distributed capaci-
1 OF 9 CHANNELS
UltraMAX
DATA OUTPUT
PIN DB(0)
Copyright © 1999
Rev. 0.1
3/99