differential line driver designed for applications requiring ultra
low power dissipation and high data rates. The device is
designed to support data rates in excess of 400.0 Mbps (200
MHz) utilizing Low Voltage Differential Signaling (LVDS)
technology.
The UT54LVDS031LV accepts low voltage TTL input levels
and translates them to low voltage (340mV) differential output
signals. In addition, the driver supports a three-state function
that may be used to disable the output stage, disabling the load
current, and thus dropping the device to an ultra low idle power
state.
The UT54LVDS031LV and companion quad line receiver
UT54LVDS032LV provide new alternatives to high power
pseudo-ECL devices for high speed point-to-point interface
applications.
All pins have Cold Spare buffers. These buffers will be high
impedance when V
DD
is tied to V
SS
.
D
IN1
D
OUT1+
D1
D
OUT1-
D
IN2
D
OUT2+
D2
D
OUT2-
D
OUT3+
D3
D
OUT3-
D
OUT4+
D4
D
OUT4-
D
IN3
D
IN4
EN
EN
Figure 1. UT54LVDS031LV Quad Driver Block Diagram
1
APPLICATIONS INFORMATION
The UT54LVDS031LV driver’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 such as 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.
D
IN1
D
OUT1+
D
OUT1-
EN
D
OUT2-
D
OUT2+
D
IN2
V
SS
1
2
3
4
5
6
7
8
UT54LVDS031LV
Driver
16
15
14
13
12
11
10
9
V
DD
D
IN4
D
OUT4+
D
OUT4-
EN
D
OUT3-
D
OUT3+
D
IN3
Figure 2. UT54LVDS031LV Pinout
TRUTH TABLE
Enables
EN
L
EN
H
Input
D
IN
X
L
H
Z
L
H
Output
D
OUT+
D
OUT-
Z
H
L
DATA
INPUT
ENABLE
RT 100
1/4 UT54LVDS032LV
+
-
DATA
OUTPUT
1/4 UT54LVDS031LV
All other combinations
of ENABLE inputs
PIN DESCRIPTION
Pin No.
1, 7, 9, 15
2, 6, 10, 14
3, 5, 11, 13
4
12
16
8
Name
D
IN
D
OUT+
D
OUT-
EN
EN
V
DD
V
SS
Figure 3. Point-to-Point Application
Description
Driver input pin, TTL/CMOS
compatible
Non-inverting driver output pin,
LVDS levels
Inverting driver output pin,
LVDS levels
Active high enable pin, OR-ed
with EN
Active low enable pin, OR-ed
with EN
Power supply pin, +3.3V + 0.3V
Ground pin
The UT54LVDS031LV differential line driver is a balanced
current source design. A current mode driver, has a high output
impedance and supplies a constant current for a range of loads
(a voltage mode driver on the other hand supplies a constant
voltage for a range of loads). Current is switched through the
load in one direction to produce a logic state and in the other
direction to produce the other logic state. The current mode
requires
(as discussed above) that a resistive termination be
employed to terminate the signal and to complete the loop as
shown in Figure 3. AC or unterminated configurations are not
allowed. The 3.4mA loop current will develop a differential
voltage of 340mV across the 100 termination resistor which
the receiver detects with a 240mV minimum differential noise
margin neglecting resistive line losses (driven signal minus
receiver threshold (340mV - 100mV = 240mV)). The signal is
centered around +1.2V (Driver Offset, V
OS
) with respect to
ground as shown in Figure 4.
Note:
The steady-state voltage
(V
SS
) peak-to-peak swing is twice the differential voltage (V
OD
)
and is typically 680mV.
2
3V
D
IN
D
OUT-
SINGLE-ENDED
D
OUT+
V
0D
0V
V
OH
V
OS
V
OL
+V
OD
0V (DIFF.)
0V
-V
OD
D
OUT+
- D
OUT-
DIFFERENTIAL OUTPUT
Note: The footprint of the UT54LVDS031LV is the same as the
industry standard Quad Differential (RS-422) Driver.
V
SS
The current mode driver provides substantial benefits over
voltage mode drivers, such as an RS-422 driver. Its quiescent
current remains relatively flat versus switching frequency.
Whereas the RS-422 voltage mode driver increases
exponentially in most cases between 20 MHz - 50 MHz. This
is due to the overlap current that flows between the rails of the
device when the internal gates switch. Whereas the current
mode driver switches a fixed current between its output without
any substantial overlap current. This is similar to some ECL
and PECL devices, but without the heavy static I
CC
requirements of the ECL/PECL design. LVDS requires 80%
less current than similar PECL devices. AC specifications for
the driver are a tenfold improvement over other existing RS-
422 drivers.
The Three-State function allows the driver outputs to be
disabled, thus obtaining an even lower power state when the
transmission of data is not required.
Figure 4. Driver Output Levels
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
LIMITS
3.0 to 3.6V
-55 to +125C
0V to V
DD
4
DC ELECTRICAL CHARACTERISTICS*
1, 2
(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
CS
V
OD1
V
OD1
V
OS
V
OS
V
CL3
I
OS2, 3
I
OZ3
I
CCL3
I
CCZ3
PARAMETER
High-level input voltage
Low-level input voltage
Low-level output voltage
High-level output voltage
Input leakage current
Cold Spare Leakage Current
Differential Output Voltage
Change in Magnitude of V
OD
for
Complementary Output States
Offset Voltage
(TTL)
(TTL)
R
L
= 100
R
L
= 100
V
IN
= V
DD
or GND, V
DD
= 3.6V
V
IN
=3.6V, V
DD
=V
SS
R
L
= 100
(figure 5)
R
L
= 100
(figure 5)
Voh + Vol
-
R
L
= 100,
Vos = --------------------------
2
CONDITION
MIN
2.0
V
SS
0.925
MAX
V
DD
0.8
UNIT
V
V
V
1.650
-10
-20
250
+10
+20
400
35
1.125
1.450
V
A
mV
mV
V
Change in Magnitude of V
OS
for
Complementary Output States
Input clamp voltage
Output Short Circuit Current
R
L
= 100
(figure 5)
I
CL
= +18mA
V
IN
= V
DD
, V
OUT+
= 0V or
V
IN
= GND, V
OUT-
= 0V
EN = 0.8V and EN = 2.0 V,
V
OUT
= 0V or V
DD,
V
DD
= 3.6V
R
L
= 100 all channels
V
IN
= V
DD
or V
SS
(all inputs)
D
IN
= V
DD
or V
SS
EN = V
SS
, EN = V
DD
-10
-1.5
25
mV
V
9.0
mA
Output Three-State Current
+10
Loaded supply current, drivers
enabled
Loaded supply current, drivers
disabled
mA
18.0
mA
3.0
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 except differential voltages.
2. Output short circuit current (I
OS
) is specified as magnitude only, minus sign indicates direction only.
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