The LX5111/5112 SCSI terminators are part of
Linfinity's UltraMAX family of high-performance,
adaptive, non-linear mode SCSI products, which
are designed to deliver true UltraSCSI performance
in SCSI applications. The low voltage BiCMOS
architecture employed in their design offers superior performance to older linear passive and
active techniques. Linfinity's UltraMAX architecture
employs high-speed adaptive elements for each
channel, thereby providing the fastest response
possible — typically 35MHz, which is 100 times
faster than the older linear regulator/terminator
approach used by other manufacturers. Products
using this older linear regulator approach have
bandwidths which are dominated by the output
capacitor and which are limited to 500KHz (see
further discussion in the Functional Description
section). The UltraMAX architecture also eliminates
the output compensation capacitor typical in earlier
terminator designs. Each is approved for use with
SCSI-1, -2, -3, UltraSCSI and beyond — providing
the highest performance alternative available today.
Another key improvement offered by the
LX5111/5112 lies in their ability to insure reliable,
error-free communications even in systems which
do not adhere to recommended SCSI hardware
design guidelines, such as the use of improper
IMPORTANT: For the most current data, consult LinFinity's web site: http://www.linfinity.com.
cable lengths and impedances. Frequently, this
situation is not controlled by the peripheral or host
designer and, when problems occur, they are the
first to be made aware of the problem. The
LX5111/5112 architecture is much more tolerant
of marginal system integrations.
Recognizing the needs of portable and
configurable peripherals, the LX5111/5112 have
a TTL compatible sleep/disable mode. Quiescent
current is typically less than 275µA in this mode,
while the output capacitance is also less than 3pF.
The obvious advantage of extended battery life
for portable systems is inherent in the product's
sleep-mode feature. Additionally, the disable
function permits factory-floor or production-line
configurability, reducing inventory and productline diversity costs. Field configurability can also
be accomplished without physically removing
components which, often times results in field
returns due to mishandling.
Reduced component counts is also inherent in
the LX5111/5112's architecture. Traditional termination techniques require large stabilization and
transient protection capacitors of up to 20µF in
value and size. The LX5111/5112 architecture
does not require these components, allowing all
the cost savings associated with inventory, board
space, assembly, reliability, and component costs.
Termination VoltageV
High Level Enable Input VoltageLX5111V
Symbol
TERM
IH
LX5112
Low Level Disable Input VoltageLX5111V
IL
LX5112
Operating Virtual Junction Temperature Range
LX5111C/5112C
Note 2. Range over which the device is functional.
ELECTRICAL CHARACTERISTICS
Term Power = 4.75V unless otherwise specified. Unless otherwise specified, these specifications apply at the recommended operating ambient temperature of T
= 25°C. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature.
A
Parameter
Output High VoltageV
TermPwr Supply CurrentI
Symbol
OUT
CC
Test ConditionsUnits
All data lines = open
All data lines = 0.5V
LX5111DISCONNECT Pin < 0.8V
LX5112DISCONNECT Pin > 2.0V
V
Output CurrentI
DISCONNECT Input Current LX5111I
OUT
IN
= 0.5V
OUT
DISCONNECT Pin = 4.75V
DISCONNECT Pin = 0V
DISCONNECT Input Current LX5112I
DISCONNECT Pin = 0V
IN
DISCONNECT Pin = 4.75V
Output Leakage CurrentLX5111I
LX5112DISCONNECT Pin = > 2.0V, V
Capacitance in DISCONNECT ModeC
DISCONNECT Pin = < 0.8V, VO = 0.5V
OL
OUTVOUT
= 0V, frequency = 1MHz
= 0.5V
O
Channel BandwidthBW
Termination Sink Current, per ChannelI
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 110Ω), are
a compromise. As the line voltage
increases, the amount of current
decreases linearly by the equation
V = I * R. The LX5111/5112, with
their unique new architecture applies the maximum amount of
current regardless of line voltage
until the termination high threshold
POWER UP / POWER DOWN FUNCTION TABLE
LX5111LX5112
DISCONNECT DISCONNECT
HLEnabled6mA
LHHI Z275µA
OpenOpenHI Z275µA
(2.85V) is reached.
Acting as a near ideal line terminators, the LX5111/5112
closely reproduce the optimum case when the devices are
enabled. To enable the device the DISCONNECT pin
(DISCONNECT pin for the LX5112) must be pulled logic High
(logic Low for the LX5112). During this mode of operation,
quiescent current is 6mA and the devices will respond to line
demands by delivering 24mA on assertion, and by imposing
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.
UltraMAX is a trademark of Linfinity Microelectronics Inc.
2.85V on deassertion. In order to disable the device, the
DISCONNECT pin (DISCONNECT pin for the LX5112) must be
driven logic Low (logic High for the LX5112). This mode of
operation places the devices in a sleep state where a meager
275µA of quiescent current is consumed. Additionally, all outputs
are in a Hi-Z (impedance) state.
Sleep mode can be used for power
Outputs
Quiescent
Current
conservation or to completely eliminate the terminator from the SCSI
chain. In the second case, termination node capacitance is important to consider. The terminators
will appear as a parasitic distributed
capacitance on the line, which can
detract from bus performance. For
this reason, the LX5111/5112 have been optimized to have only
3pF of capacitance per output in the sleep state.
An additional feature of the LX5111/5112 IC's are their
compatibility with active negation drivers. These devices handle
up to 60mA of sink current for drivers which exceed the 2.85V
output high.