Standard Products
UT54LVDM328 Octal 400 Mbps
Bus LVDS Repeater
Data Sheet
September, 2015
The most important thing we build is trust
FEATURES
400.0 Mbps low jitter fully differential data path
200MHz clock channel
3.3 V power supply
10mA LVDS output drivers
Cold sparing all pins
Fast propagation delay of 3.5ns max
Receiver input threshold < + 100 mV
Operational environment; total dose irradiation testing to MIL-
STD-883 Method 1019
- Total-dose: 300 krad(Si) and 1 Mrad(Si)
- Latchup immune (LET > 100 MeV-cm
2
/mg)
Packaging options:
- 48-lead flatpack (1.4 grams)
Standard Microcircuit Drawing 5962-01536
- QML Q and V compliant part
Compatible with TIA/EIA-899
INTRODUCTION
The UT54LVDM328 is an Octal Bus Repeater utilizing Low
Voltage Differential Signaling (LVDS) technology for low power,
high speed operation. Data paths are fully differential from input
to output for low noise generation and low pulse width distortion.
LVDS I/O enable high speed data transmission for point-to point
or multi-drop interconnects. This device is designed for use as a
high speed differential repeater.
The UT54LVDM328 is a repeater designed specifically for the
bridging of multiple backplanes in a system. The UT54LVDM328
utilizes low voltage differential signaling to deliver high speed
while consuming minimal power with reduced EMI. The
UT54LVDM328 repeats signals between backplanes and accepts
or drives signals onto the local bus.
The individual LVDS outputs can be put into Tri-State by use of
the enable pins.
All pins have Cold Spare buffers. These buffers will be high
impedance when V
DD
is tied to V
SS
.
END
IN1+
IN1-
+
-
OUT1+
OUT1-
IN2+
IN2-
+
-
OUT2+
OUT2-
Figure 1a. UT54LVDM328 Repeater Block Diagram
(Partial - see Page 2 for complete diagram)
36-00-06-011
Version 1.0.1
1
Cobham Semiconductor Solutions
www.aeroflex.com/LVDS
APPLICATIONS INFORMATION
The UT54LVDM328 provides the basic bus repeater
function. The device operates as a 9 channel LVDS buffer.
Repeating the signal restores the LVDS amplitude, allowing
it to drive another media segment. This allows for isolation
of segments or long distance applications.
The intended application of these devices and signaling
technique is for both point-to-point baseband (single
termination) and multipoint (double termination) data
transmissions over controlled impedance media. The
transmission media may be printed-circuit board traces,
backplanes, or cables. (Note: The ultimate rate and distance
of data transfer is dependent upon the attenuation
characteristics of the media, the noise coupling to the
environment, and other application specific characteristics.)
Input Fail-Safe:
The UT54LVDM328 also supports OPEN, shorted and
terminated input fail-safe. Receiver output will be HIGH for
all fail-safe conditions.
PCB layout and Power System Bypass:
Circuit board layout and stack-up for the UT54LVDM328
should be designed to provide noise-free power to the device.
Good layout practice also will separate high frequency or high
level inputs and outputs to minimize unwanted stray noise
pickup, feedback and interference. Power system
performance may be greatly improved by using thin
dielectrics (4 to 10 mils) for power/ground sandwiches. This
increases the intrinsic capacitance of the PCB power system
which improves power supply filtering, especially at high
frequencies, and makes the value and placement of external
bypass capacitors less critical. External bypass capacitors
should include both RF ceramic and tantalum electrolytic
types. RF capacitors may use values in the range 0.01F to
0.1 F. Tantalum capacitors may be in the range of 2.2F to
10F. Voltage rating for tantalum capacitors should be at least
5X the power supply voltage being used. It is recommended
practice to use two vias at each power pin of the
UT54LVDM328, as well as all RF bypass capacitor
terminals. Dual vias reduce the interconnect inductance and
extends the effective frequency range of the bypass
components.
The outer layers of the PCB may be flooded with additional
ground plane. These planes will improve shielding and
isolation, as well as increase the intrinsic capacitance of the
power supply plane system. Naturally, to be effective, these
planes must be tied to the ground supply plane at frequent
intervals with vias. Frequent via placement also improves
signal integrity in signal transmission lines by providing short
paths for image currents which reduces signal distortion. The
planes should be pulled back from all transmission lines and
component mounting pads a distance equal to the width of
the widest transmission line from the internal power or
ground plane(s) whichever is greater. Doing so minimizes
effects on transmission line impedances and reduces
unwanted parasitic capacitances at component mounting
pads.
Compatibility with LVDS standard:
In backplane multidrop configurations, with closely spaced
loads, the effective differential impedance of the line is
reduced. If the mainline has been designed for 50
differential impedance, the loading effects may reduce this to
the 35 range depending upon spacing and capacitance load.
Terminating the line with a 35 load is a better match than
with 50 and reflections are reduced.
3
OPERATIONAL ENVIRONMENT
PARAMETER
Total Ionizing Dose (TID)
Single Event Latchup (SEL)
Neutron Fluence
1
Notes:
1. Guarnteed but not tested.
LIMIT
1.0E6
>100
1.0E13
(Referenced to V
SS
)
UNITS
rad(Si)
MeV-cm
2
/mg
n/cm
2
ABSOLUTE MAXIMUM RATINGS
1
SYMBOL
V
DD
V
I/O
T
STG
P
D
T
J
JC
I
I
PARAMETER
DC supply voltage
Voltage on any pin
Storage temperature
Maximum power dissipation permitted @
Tc = +125
o
C
Maximum junction temperature
2
Thermal resistance, junction-to-case
3
DC input current
LIMITS
-0.3 to 4.0V
-0.3 to (V
DD
+ 0.3V)
-65 to +150C
1.667 W
+150C
15C/W
±
10mA
3. Test per MIL-STD-883, Method 1012.
4. For cold spare mode (V
DD
= V
SS
), V
I/O
may be -0.3V to the maximum
recommended operating V
DD
+0.3V.
5. Per MIL-STD-883, Method 1012.1, Section 3.4.1, PD = (T
J
(max) - Tc(max) /
JC
.
Notes:
1. Stresses outside the listed absolute maximum ratings may cause permanent
damage to the device. This is a stress rating only, and functional operation of the
device at these or any other conditions beyond limits indicated in the operational
sections of this specification is not recommended. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability
and performance.
2. Maximum junction temperature may be increased to +175C during burn-in and
life test.
RECOMMENDED OPERATING CONDITIONS
LIMITS
3.0 to 3.6V
-55 to +125C
0 to 2.4V
0 to V
DD
for END or ENCK
SYMBOL
V
DD
T
C
V
IN
PARAMETER
Positive supply voltage
Case temperature range
DC input voltage, receiver inputs
DC input voltage, logic inputs
36-00-06-011
Version 1.0.1
4
Cobham Semiconductor Solutions
www.aeroflex.com/LVDS
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