The UT54LVDS032LV receiver’s intended use is primarily in an
uncomplicated point-to-point configuration as is shown in Figure
3. This configuration provides a clean signaling environment for
quick edge rates of the drivers. The receiver is connected to the
driver through a balanced media which may be a standard twisted
pair cable, a parallel pair cable, or simply PCB traces. Typically,
the characteristic impedance of the media is in the range of 100.
A termination resistor of 100should be selected to match the
media and is located as close to the receiver input pins as possible.
The termination resistor converts the current sourced by the driver
into voltages that are detected by the receiver. Other configurations
are possible such as a multi-receiver configuration, but the effects
of a mid-stream connector(s), cable stub(s), and other impedance
discontinuities, as well as ground shifting, noise margin limits, and
total termination loading must be taken into account.
R
IN1-
R
IN1+
R
OUT1
EN
R
OUT2
R
IN2+
R
IN2-
V
SS
1
2
3
4
5
6
7
8
UT54LVDS032LV
Receiver
16
15
14
13
12
11
10
9
V
DD
R
IN4-
R
IN4+
R
OUT4
EN
R
OUT3
R
IN3+
R
IN3-
Figure 2. UT54LVDS032LV Pinout
ENABLE
TRUTH TABLE
Enables
EN
L
EN
H
Input
R
IN+
- R
IN
-
X
V
ID
> 0.1V
V
ID
< -0.1V
Full Fail-safe
OPEN/SHORT or
Terminated
PIN DESCRIPTION
Pin No.
2, 6, 10, 14
1, 7, 9, 15
3, 5, 11, 13
4
12
16
8
Name
R
IN+
R
IN-
R
OUT
EN
EN
V
DD
V
SS
Description
Non-inverting receiver input pin
Inverting receiver input pin
Receiver output pin
Active high enable pin, OR-ed
with EN
Active low enable pin, OR-ed
with EN
Power supply pin, +3.3 + 0.3V
Ground pin
Output
R
OUT
Z
H
L
H
DATA
INPUT
1/4 UT54LVDS031LV
RT 100
1/4 UT54LVDS032LV
+
-
DATA
OUTPUT
Figure 3. Point-to-Point Application
All other combinations
of ENABLE inputs
The UT54LVDS032LV differential line receiver is capable of
detecting signals as low as 100mV, over a + 1V common-mode
range centered around +1.2V. This is related to the driver offset
voltage which is typically +1.2V. The driven signal is centered
around this voltage and may shift +1V around this center point.
The +1V shifting may be the result of a ground potential difference
between the driver’s ground reference and the receiver’s ground
reference, the common-mode effects of coupled noise or a
combination of the two. Both receiver input pins should honor their
specified operating input voltage range of 0V to +2.4V (measured
from each pin to ground).
Receiver Fail-Safe
36-00-06-005
Version 1.0.1
2
Cobham Semiconductor Solutions
www.aeroflex.com/LVDS
The UT54LVDS032LV receiver is a high gain, high speed
device that amplifies a small differential signal (20mV) to TTL
logic levels. Due to the high gain and tight threshold of the
receiver, care should be taken to prevent noise from appearing
as a valid signal.
The receiver’s internal fail-safe circuitry is designed to source/
sink a small amount of current, providing fail-safe protection
(a stable known state of HIGH output voltage) for floating,
terminated or shorted receiver inputs.
1.
Open Input Pins.
The UT54LVDS032LV is a quad
receiver device, and if an application requires only 1, 2
or 3 receivers, the unused channel(s) inputs should be
left OPEN. Do not tie unused receiver inputs to ground
or any other voltages. The input is biased by internal
high value pull up and pull down resistors to set the
output to a HIGH state. This internal circuitry will
guarantee a HIGH, stable output state for open inputs.
2.
Terminated Input.
If the driver is disconnected (cable
unplugged), or if the driver is in a three-state or power-
off condition, the receiver output will again be in a
HIGH state, even with the end of cable 100
termination resistor across the input pins. The
unplugged cable can become a floating antenna which
can pick up noise. If the cable picks up more than 10mV
of differential noise, the receiver may see the noise as
a valid signal and switch. To insure that any noise is
seen as common-mode and not differential, a balanced
interconnect should be used. Twisted pair cable offers
better balance than flat ribbon cable.
3.
Shorted Inputs.
If a fault condition occurs that shorts
the receiver inputs together, thus resulting in a 0V
differential input voltage, the receiver output remains
in a HIGH state. Shorted input fail-safe is not supported
across the common-mode range of the device (V
SS
to
2.4V). It is only supported with inputs shorted and no
external common-mode voltage applied.
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
UNITS
rad(Si)
MeV-cm
2
/mg
n/cm
2
ABSOLUTE MAXIMUM RATINGS
1
(Referenced to V
SS
)
SYMBOL
V
DD
V
I/O
PARAMETER
DC supply voltage
Voltage on any pin during operation
Voltage on any pin during cold spare
T
STG
P
D
T
J
JC
I
I
Storage temperature
Maximum power dissipation
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)
-.3 to 4.0V
-65 to +150C
1.25 W
+150C
10C/W
±
10mA
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.
3. Test per MIL-STD-883, Method 1012.
RECOMMENDED OPERATING CONDITIONS
SYMBOL
V
DD
T
C
V
IN
PARAMETER
Positive supply voltage
Case temperature range
DC input voltage, receiver inputs
DC input voltage, logic inputs
LIMITS
3.0 to 3.6V
-55 to +125C
2.4V
0 to V
DD
for EN, EN
DC ELECTRICAL CHARACTERISTICS*
1
(V
DD
= 3.3V + 0.3V; -55C < T
C
< +125C); Unless otherwise noted, Tc is per the temperature range ordered
SYMBOL
V
IH
V
IL
V
OL
V
OH
I
IN
I
I
I
CS
V
TH3
V
TL3
I
OZ3
V
CL
I
OS2, 3
I
CC3
I
CCZ3
PARAMETER
High-level input voltage
Low-level input voltage
Low-level output voltage
High-level output voltage
Logic input leakage current
(TTL)
(TTL)
I
OL
= 2mA, V
DD
= 3.0V
I
OH
= -0.4mA, V
DD
= 3.0V
Enables = EN/EN = 0 and 3.6V,
V
DD
= 3.6
V
IN
= 2.4V
V
IN
=3.6V, V
DD
=V
SS
V
CM
= +1.2V
V
CM
= +1.2V
Disabled, V
OUT
= 0 V or V
DD
I
CL
= +18mA
Enabled, V
OUT
= 0 V
2
EN, EN = V
DD
or V
SS
Inputs Open
EN = V
SS
, EN = V
DD
Inputs Open
-100
-10
-1.5
-15
-130
15
+10
2.7
-10
+10
CONDITION
MIN
2.0
0.8
0.25
MAX
UNIT
V
V
V
V
A
mV
mV
V
mA
mA
Receiver input Current
Cold Spare Leakage Current
Differential Input High Threshold
Differential Input Low Threshold
Output Three-State Current
Input clamp voltage
Output Short Circuit Current
Supply current, receivers enabled
-15
-20
+15
+20
+100
Supply current, receivers disabled
mA
4
Notes:
* For devices procured with a total ionizing dose tolerance guarantee, the post-irradiation performance is guaranteed at 25
o
C per MIL-STD-883 Method 1019, Condition
A up to the maximum TID level procured.
1. Current into device pins is defined as positive. Current out of device pins is defined as negative. All voltages are referenced to ground.
2. Output short circuit current (I
OS
) is specified as magnitude only, minus sign indicates direction only. Only one output should be shorted at a time, do not exceed maximum
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