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 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
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
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
ENABLE
RT 100Ω
1/4 UT54LVDS032LV
+
-
DATA
OUTPUT
1/4 UT54LVDS031LV
All other combinations
of ENABLE inputs
Figure 3. Point-to-Point Application
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).
2
Receiver Fail-Safe
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 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.
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
Θ
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 +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 life test.
3. Test per MIL-STD-883, Method 1012.
3
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 +125°C
2.4V
0 to V
DD
for EN, EN
4
DC ELECTRICAL CHARACTERISTICS
1
(V
DD
= 3.3V + 0.3V; -55°C < T
C
< +125°C)
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
µA
µΑ
µΑ
mV
mV
µΑ
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:
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
1 Introduction
In the mid-1960s, American scientist Maas conducted extensive experimental research on the charging process of open-cell batteries and proposed an acceptable charging curve for ...[详细]
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