The UT54LVDSC032 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 100Ω. A termination resistor of 100Ω
should 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
UT54LVDSC032
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. UT54LVDSC032 Pinout
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, +5V + 10%
Ground pin
Output
R
OUT
Z
H
L
H
DATA
INPUT
ENABLE
RT 100Ω
1/4 UT54LVDSC032
+
-
DATA
OUTPUT
1/4 UT54LVDS031
All other combinations
of ENABLE inputs
Figure 3. Point-to-Point Application
The UT54LVDSC032 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
2
The UT54LVDSC32 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 UT54LVDSC032 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 100Ω 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
ABSOLUTE MAXIMUM RATINGS
1
(Referenced to V
SS
)
SYMBOL
V
DD
V
I/O4
PARAMETER
DC supply voltage
Voltage on any pin during operation
Voltage on LVDS inputs during cold spare
T
STG
P
D
T
J
Θ
JC
I
I
Storage temperature
Maximum power dissipation
Maximum junction temperature
2
Thermal resistance, junction-to-case
3
DC input current
LIMITS
-0.3V to 6.0V
-0.3V to (V
DD
+ 0.3V)
-0.3V to 6.0V
-65 to +150°C
1.25 W
+150°C
10°C/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 +175°C during burn-in and steady-static life.
3. Test per MIL-STD-883, Method 1012.
4. During cold spare, all pins except LVDS inputs should not exceed ±0.3V.
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
4.5 to 5.5V
-55 to +125°C
2.4V
0 to V
DD
for EN, EN
4
DC ELECTRICAL CHARACTERISTICS
1
SYMBOL
V
IH
V
IL
V
OL
V
OH
I
IN
PARAMETER
High-level input voltage
Low-level input voltage
Low-level output voltage
High-level output voltage
Logic input leakage current
(TTL)
(TTL)
(V
DD
= 5.0V +10%; -55°C < T
C
< +125°C)
CONDITION
MIN
2.0
0.8
0.3
4.0
-10
-10
+10
+10
MAX
UNIT
V
V
V
V
µA
I
OL
= 2mA, V
DD
= 4.5V
I
OH
= -0.4mA, V
DD
= 4.5V
Inputs, V
IN
= 0 and 2.4V, V
CC
= 5.5
Enables = EN/EN= 0 and 5.5V,
V
CC
= 5.5
I
CSIN
V
TH3
V
TL3
I
I
I
OZ4
V
CL
I
OS3
I
CC4
I
CCZ4
Cold Spare Leakage LVDS Inputs
Differential Input High Threshold
Differential Input Low Threshold
Receiver input Current
Output Three-State Current
Input clamp voltage
Output Short Circuit Current
Loaded supply current receivers
enabled
Loaded supply current receivers
disabled
V
IN
=5.5V, V
DD
=V
SS
V
CM
= +1.2V
V
CM
= +1.2V
V
IN
= 2.4V
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
-10
+10
+100
µΑ
mV
mV
-100
-10
-10
-1.5
-15
+10
+10
1.5
-130
11
µΑ
µΑ
V
mA
mA
mA
11
Notes:
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
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