DS90LV031A
3V LVDS Quad CMOS Differential Line Driver
General Description
The DS90LV031A is a quad CMOS differential line driver de-
signed for applications requiring ultra low power dissipation
and high data rates. The device is designed to support data
rates in excess of 400 Mbps (200 MHz) utilizing Low Voltage
Differential Signaling (LVDS) technology.
The DS90LV031A accepts low voltage TTL/CMOS input lev-
els and translates them to low voltage (350 mV) differential
output signals. In addition the driver supports a TRI-STATE
function that may be used to disable the output stage, dis-
abling the load current, and thus dropping the device to an
ultra low idle power state of 13 mW typical.
The EN and EN* inputs allow active Low or active High con-
trol of the TRI-STATE outputs. The enables are common to
all four drivers. The DS90LV031A and companion line re-
ceiver (DS90LV032A) provide a new alternative to high
power psuedo-ECL devices for high speed point-to-point in-
terface applications.
Features
n
>
400 Mbps (200 MHz) switching rates
n
0.1 ns typical differential skew
n
0.4 ns maximum differential skew
n
2.0 ns maximum propagation delay
n
3.3V power supply design
n
350 mV differential signaling
n
Low power dissipation (13mW at 3.3V static)
n
Interoperable with existing 5V LVDS devices
n
Compatible with IEEE 1596.3 SCI LVDS standard
n
Compatible with TIA/EIA-644 LVDS standard
n
Industrial and Military operating temperature range
n
Available in SOIC, TSSOP and Cerpack surface mount
packaging
n
Standard Microcircuit Drawing (SMD) 5962-9865201
Connection Diagram
Functional Diagram
Truth Table
DRIVER
Enables
Input
Outputs
EN
EN
*
D
IN
D
OUT+
D
OUT-
L
H
X
Z
Z
All other combinations of
ENABLE inputs
L
L
H
H
H
L
TRI-STATE
is a registered trademark of National Semiconductor Corporation.
Dual-In-Line
DS100095-1
Order Number DS90LV031ATM
or DS90LV031ATMTC
or DS90LV031AW
See NS Package Number M16A or MTC16 or W16A
DS100095-2
July 1999
DS90L
V031A
3V
L
VDS
Quad
CMOS
Differential
Line
Driver
1999 National Semiconductor Corporation
DS100095
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (V
CC
)
-0.3V to +4V
Input Voltage (D
IN
)
-0.3V to (V
CC
+ 0.3V)
Enable Input Voltage (EN, EN
*
)
-0.3V to (V
CC
+ 0.3V)
Output Voltage (D
OUT+
, D
OUT-
)
-0.3V to +3.9V
Short Circuit Duration
(D
OUT+
, D
OUT-
)
Continuous
Maximum Package Power Dissipation
@
+25C
M Package
1088 mW
MTC Package
866 mW
W Package
845 mW
Derate M Package
8.5 mW/C above +25C
Derate MTC Package
6.9 mW/C above +25C
Derate W Package
6.8 mW/C above +25C
Storage Temperature Range
-65C to +150C
Lead Temperature Range
Soldering (4 sec.)
+260C
Maximum Junction Temperature
+150C
ESD Rating (Note 10)
(HBM, 1.5 k
, 100 pF)
6 kV
Recommended Operating
Conditions
Min
Typ
Max
Units
Supply Voltage (V
CC
)
+3.0
+3.3
+3.6
V
Operating Free Air
Temperature (T
A
)
Industrial
-40
+25
+85
C
Military
-55
+25
+125
C
Electrical Characteristics
Over supply voltage and operating temperature ranges, unless otherwise specified. (Notes 2, 3, 4)
Symbol
Parameter
Conditions
Pin
Min
Typ
Max
Units
V
OD1
Differential Output Voltage
R
L
= 100
(
Figure 1)
D
OUT-
D
OUT+
250
350
450
mV
V
OD1
Change in Magnitude of V
OD1
for Complementary Output
States
4
35
|mV|
V
OS
Offset Voltage
1.125
1.25
1.375
V
V
OS
Change in Magnitude of V
OS
for
Complementary Output States
5
25
|mV|
V
OH
Output Voltage High
1.38
1.6
V
V
OL
Output Voltage Low
0.90
1.03
V
V
IH
Input Voltage High
D
IN
,
EN,
EN*
2.0
V
CC
V
V
IL
Input Voltage Low
GND
0.8
V
I
IH
Input Current
V
IN
= V
CC
or 2.5V
-10
1
+10
A
I
IL
Input Current
V
IN
= GND or 0.4V
-10
1
+10
A
V
CL
Input Clamp Voltage
I
CL
= -18 mA
-1.5
-0.8
V
I
OS
Output Short Circuit Current
ENABLED, (Note 11)
D
IN
= V
CC
, D
OUT+
= 0V or
D
IN
= GND, D
OUT-
= 0V
D
OUT-
D
OUT+
-6.0
-9.0
mA
I
OSD
Differential Output Short Circuit
Current
ENABLED, V
OD
= 0V
(Note 11)
-6.0
-9.0
mA
I
OFF
Power-off Leakage
V
OUT
= 0V or 3.6V,
V
CC
= 0V or Open
-20
1
+20
A
I
OZ
Output TRI-STATE Current
EN = 0.8V and EN* = 2.0V
V
OUT
= 0V or V
CC
-10
1
+10
A
I
CC
No Load Supply Current Drivers
Enabled
D
IN
= V
CC
or GND
V
CC
5.0
8.0
mA
I
CCL
Loaded Supply Current Drivers
Enabled
R
L
= 100
All Channels, D
IN
=
V
CC
or GND (all inputs)
23
30
mA
I
CCZ
No Load Supply Current Drivers
Disabled
D
IN
= V
CC
or GND,
EN = GND, EN* = V
CC
2.6
6.0
mA
www.national.com
2
Switching Characteristics - Industrial
V
CC
= +3.3V
10%, T
A
= -40C to +85C (Notes 3, 9, 12)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
t
PHLD
Differential Propagation Delay High to Low
R
L
= 100
, C
L
= 10 pF
(
Figure 2 and Figure 3)
0.8
1.18
2.0
ns
t
PLHD
Differential Propagation Delay Low to High
0.8
1.25
2.0
ns
t
SKD1
Differential Pulse Skew |t
PHLD
- t
PLHD
|
(Note 5)
0
0.07
0.4
ns
t
SKD2
Channel-to-Channel Skew (Note 6)
0
0.1
0.5
ns
t
SKD3
Differential Part to Part Skew (Note 7)
0
1.0
ns
t
SKD4
Differential Part to Part Skew (Note 8)
0
1.2
ns
t
TLH
Rise Time
0.38
1.5
ns
t
THL
Fall Time
0.40
1.5
ns
t
PHZ
Disable Time High to Z
R
L
= 100
, C
L
= 10 pF
(
Figure 4 and Figure 5)
5
ns
t
PLZ
Disable Time Low to Z
5
ns
t
PZH
Enable Time Z to High
7
ns
t
PZL
Enable Time Z to Low
7
ns
f
MAX
Maximum Operating Frequency (Note 14)
200
250
MHz
Switching Characteristics - Military
V
CC
= +3.3V
10%, T
A
= -55C to +125C (Notes 9, 12)
Symbol
Parameter
Conditions
Min
Max
Units
t
PHLD
Differential Propagation Delay High to Low
R
L
= 100
, C
L
= 10 pF
(
Figure 2 and Figure 3)
0.8
2.0
ns
t
PLHD
Differential Propagation Delay Low to High
0.8
2.0
ns
t
SKD1
Differential Pulse Skew |t
PHLD
- t
PLHD
|
(Note 5)
0
0.4
ns
t
SKD2
Channel-to-Channel Skew (Note 6)
0
0.5
ns
t
SKD3
Differential Part to Part Skew (Note 7)
0
1.0
ns
t
SKD4
Differential Part to Part Skew (Note 8)
0
1.2
ns
t
TLH
Rise Time
1.5
ns
t
THL
Fall Time
1.5
ns
t
PHZ
Disable Time High to Z
R
L
= 100
, C
L
= 10 pF
(
Figure 4 and Figure 5)
5
ns
t
PLZ
Disable Time Low to Z
5
ns
t
PZH
Enable Time Z to High
7
ns
t
PZL
Enable Time Z to Low
7
ns
f
MAX
Maximum Operating Frequency (Note 14)
200
MHz
Note 1: "Absolute Maximum Ratings" are those values beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the devices
should be operated at these limits. The table of "Electrical Characteristics" specifies conditions of device operation.
Note 2: Current into device pins is defined as positive. Current out of device pins is defined as negative. All voltages are referenced to ground except: V
OD1
and
V
OD1
.
Note 3: All typicals are given for: V
CC
= +3.3V, T
A
= +25C.
Note 4: The DS90LV031A is a current mode device and only functions within datasheet specifications when a resistive load is applied to the driver outputs typical
range is (90
to 110
)
Note 5: t
SKD1
, |t
PHLD
- t
PLHD
| is the magnitude difference in differential propagation delay time between the positive going edge and the negative going edge of the
same channel.
Note 6: t
SKD2
is the Differential Channel-to-Channel Skew of any event on the same device.
Note 7: t
SKD3
, Differential Part to Part Skew, is defined as the difference between the minimum and maximum specified differential propagation delays. This speci-
fication applies to devices at the same V
CC
and within 5C of each other within the operating temperature range.
Note 8: t
SKD4
, part to part skew, is the differential channel-to-channel skew of any event between devices. This specification applies to devices over recommended
operating temperature and voltage ranges, and across process distribution. t
SKD4
is defined as |Max - Min| differential propagation delay.
Note 9: Generator waveform for all tests unless otherwise specified: f = 1 MHz, Z
O
= 50
, t
r
1 ns, and t
f
1 ns.
Note 10: ESD Ratings:
HBM (1.5 k
, 100 pF)
6 kV
Note 11: Output short circuit current (I
OS
) is specified as magnitude only, minus sign indicates direction only.
Note 12: C
L
includes probe and jig capacitance.
Note 13: All input voltages are for one channel unless otherwise specified. Other inputs are set to GND.
Note 14: f
MAX
generator input conditions: t
r
= t
f
<
1ns, (0% to 100%), 50% duty cycle, 0V to 3V. Output Criteria: duty cycle = 45%/55%, VOD
>
250mV, all channels
switching.
www.national.com
3
Parameter Measurement Information
DS100095-3
FIGURE 1. Driver V
OD
and V
OS
Test Circuit
DS100095-4
FIGURE 2. Driver Propagation Delay and Transition Time Test Circuit
DS100095-5
FIGURE 3. Driver Propagation Delay and Transition Time Waveforms
DS100095-6
FIGURE 4. Driver TRI-STATE Delay Test Circuit
www.national.com
4
Parameter Measurement Information
(Continued)
Typical Application
Applications Information
General application guidelines and hints for LVDS drivers
and receivers may be found in the following application
notes: LVDS Owner's Manual (lit #550062-001), AN808,
AN1035, AN977, AN971, AN916, AN805, AN903.
LVDS drivers and receivers are intended to be primarily used
in an uncomplicated point-to-point configuration as is shown
in
Figure 6. This configuration provides a clean signaling en-
vironment for the quick edge rates of the drivers. The re-
ceiver 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 dif-
ferential impedance of the media is in the range of 100
. A
termination resistor of 100
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 a voltage that is detected by the re-
ceiver. 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 disconti-
nuities as well as ground shifting, noise margin limits, and to-
tal termination loading must be taken into account.
The DS90LV031A differential line driver is a balanced cur-
rent source design. A current mode driver, generally speak-
ing 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 pro-
duce a logic state and in the other direction to produce the
other logic state. The output current is typically 3.5 mA, a
minimum of 2.5 mA, and a maximum of 4.5 mA. The current
mode requires (as discussed above) that a resistive termi-
nation be employed to terminate the signal and to complete
the loop as shown in
Figure 6. AC or unterminated configu-
rations are not allowed. The 3.5 mA loop current will develop
a differential voltage of 350 mV across the 100
termination
resistor which the receiver detects with a 250 mV minimum
differential noise margin neglecting resistive line losses
(driven signal minus receiver threshold (350 mV 100 mV =
250 mV)). The signal is centered around +1.2V (Driver Off-
set, V
OS
) with respect to ground as shown in
Figure 7. Note
that the steady-state voltage (V
SS
) peak-to-peak swing is
twice the differential voltage (V
OD
) and is typically 700 mV.
The current mode driver provides substantial benefits over
voltage mode drivers, such as an RS-422 driver. Its quies-
cent current remains relatively flat versus switching fre-
quency. Whereas the RS-422 voltage mode driver increases
exponentially in most case between 20 MHz50 MHz. This
is due to the overlap current that flows between the rails of
the device when the internal gates switch. Whereas the cur-
rent 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 designs. LVDS requires
>
80% less current than similar PECL devices. AC specifica-
tions for the driver are a tenfold improvement over other ex-
isting RS-422 drivers.
DS100095-7
FIGURE 5. Driver TRI-STATE Delay Waveform
DS100095-8
FIGURE 6. Point-to-Point Application
www.national.com
5
Applications Information
(Continued)
The TRI-STATE function allows the driver outputs to be dis-
abled, thus obtaining an even lower power state when the
transmission of data is not required.
The footprint of the DS90LV031A is the same as the industry
standard 26LS31 Quad Differential (RS-422) Driver and is a
step down replacement for the 5V DS90C031 Quad Driver.
Power Decoupling Recommendations:
Bypass capacitors must be used on power pins. High fre-
quency ceramic (surface mount is recommended) 0.1F in
parallel with 0.01F, in parallel with 0.001F at the power
supply pin as well as scattered capacitors over the printed
circuit board. Multiple vias should be used to connect the de-
coupling capacitors to the power planes. A 10F (35V) or
greater solid tantalum capacitor should be connected at the
power entry point on the printed circuit board.
PC Board considerations:
Use at least 4 PCB layers (top to bottom); LVDS signals,
ground, power, TTL signals.
Isolate TTL signals from LVDS signals, otherwise the TTL
may couple onto the LVDS lines. It is best to put TTL and
LVDS signals on different layers which are isolated by a
power/ground plane(s).
Keep drivers and receivers as close to the (LVDS port side)
connectors as possible.
Differential Traces:
Use controlled impedance traces which match the differen-
tial impedance of your transmission medium (ie. cable) and
termination resistor. Run the differential pair trace lines as
close together as possible as soon as they leave the IC
(stubs should be
<
10mm long). This will help eliminate re-
flections and ensure noise is coupled as common-mode. In
fact, we have seen that differential signals which are 1mm
apart radiate far less noise than traces 3mm apart since
magnetic field cancellation is much better with the closer
traces. Plus, noise induced on the differential lines is much
more likely to appear as common-mode which is rejected by
the receiver.
Match electrical lengths between traces to reduce skew.
Skew between the signals of a pair means a phase differ-
ence between signals which destroys the magnetic field can-
cellation benefits of differential signals and EMI will result.
(Note the velocity of propagation, v = c/Er where c (the
speed of light) = 0.2997mm/ps or 0.0118 in/ps). Do not rely
solely on the autoroute function for differential traces. Care-
fully review dimensions to match differential impedance and
provide isolation for the differential lines. Minimize the num-
ber or vias and other discontinuities on the line.
Avoid 90 turns (these cause impedance discontinuities).
Use arcs or 45 bevels.
Within a pair of traces, the distance between the two traces
should be minimized to maintain common-mode rejection of
the receivers. On the printed circuit board, this distance
should remain constant to avoid discontinuities in differential
impedance. Minor violations at connection points are allow-
able.
Termination:
Use a resistor which best matches the differential impedance
or your transmission line. The resistor should be between
90
and 130
. Remember that the current mode outputs
need the termination resistor to generate the differential volt-
age. LVDS will not work without resistor termination. Typi-
cally, connect a single resistor across the pair at the receiver
end.
Surface mount 1% to 2% resistors are best. PCB stubs,
component lead, and the distance from the termination to the
receiver inputs should be minimized. The distance between
the termination resistor and the receiver should be
<
10mm
(12mm MAX).
Probing LVDS Transmission Lines:
Always use high impedance (
>
100k
), low capacitance
(
<
2pF) scope probes with a wide bandwidth (1GHz) scope.
Improper probing will give deceiving results.
Cables and Connectors, General Comments:
When choosing cable and connectors for LVDS it is impor-
tant to remember:
Use controlled impedance media. The cables and connec-
tors you use should have a matched differential impedance
of about 100
. They should not introduce major impedance
discontinuities.
Balanced cables (e.g. twisted pair) are usually better than
unbalanced cables (ribbon cable, simple coax.) for noise re-
duction and signal quality. Balanced cables tend to generate
less EMI due to field canceling effects and also tend to pick
up electromagnetic radiation a common-mode (not differen-
tial mode) noise which is rejected by the receiver. For cable
distances
<
0.5M, most cables can be made to work effec-
tively. For distances 0.5M
d
10M, CAT 3 (category 3)
twisted pair cable works well, is readily available and rela-
tively inexpensive.
Fail-safe Feature:
The LVDS receiver is a high gain, high speed device that
amplifies a small differential signal (20mV) to CMOS logic
levels. Due to the high gain and tight threshold of the re-
ceiver, 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 DS90LV032A is a quad receiver
device, and if an application requires only 1, 2 or 3 re-
ceivers, 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 TRI-STATE or power-
off condition, the receiver output will again be in a HIGH
state, even with the end of cable 100
termination resis-
tor across the input pins. The unplugged cable can be-
come 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 will offer better balance than flat rib-
bon cable.
www.national.com
6
Applications Information
(Continued)
3.
Shorted Inputs. If a fault condition occurs that shorts
the receiver inputs together, thus resulting in a 0V differ-
ential input voltage, the receiver output will remain in a
HIGH state. Shorted input fail-safe is not supported
across the common-mode range of the device (GND to
2.4V). It is only supported with inputs shorted and no ex-
ternal common-mode voltage applied.
External lower value pull up and pull down resistors (for a
stronger bias) may be used to boost fail-safe in the presence
of higher noise levels. The pull up and pull down resistors
should be in the 5k
to 15k
range to minimize loading and
waveform distortion to the driver. The common-mode bias
point should be set to approximately 1.2V (less than 1.75V)
to be compatible with the internal circuitry.
Pin Descriptions
Pin No.
Name
Description
1, 7, 9, 15
D
IN
Driver input pin, TTL/CMOS
compatible
2, 6, 10,
14
D
OUT+
Non-inverting driver output pin,
LVDS levels
3, 5, 11,
13
D
OUT-
Inverting driver output pin, LVDS
levels
4
EN
Active high enable pin, OR-ed
with EN
*
12
EN
*
Active low enable pin, OR-ed
with EN
16
V
CC
Power supply pin, +3.3V
0.3V
8
GND
Ground pin
Ordering Information
Operating
Package Type/
Order Number
Temperature
Number
-40C to +85C
SOP/M16A
DS90LV031ATM
-40C to +85C
TSSOP/MTC16
DS90LV031ATMTC
Operating
Package Type/
Order Number
Temperature
Number
-55C to +125C
Cerpack/W16A DS90LV031AW-QML
DS100095-9
FIGURE 7. Driver Output Levels
DS100095-10
FIGURE 8. Typical DS90LV031A, D
OUT
(single ended)
vs R
L
, T
A
= 25C
www.national.com
7
Applications Information
(Continued)
DS100095-11
FIGURE 9. Typical DS90LV031A, D
OUT
vs R
L
,
V
CC
= 3.3V, T
A
= 25C
www.national.com
8
Physical Dimensions
inches (millimeters) unless otherwise noted
16-Lead (0.150" Wide) Molded Small Outline Package, JEDEC
Order Number DS90LV031ATM
NS Package Number M16A
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9
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
16-Lead (0.100" Wide) Molded Thin Shrink Small Outline Package, JEDEC
Order Number DS90LV031ATMTC
NS Package Number MTC16
www.national.com
10
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
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COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
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whose failure to perform when properly used in
accordance with instructions for use provided in the
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significant injury to the user.
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support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
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www.national.com
16-Lead Cerpack
Order Number DS90LV031AW-QML
NS Package Number W16A
DS90L
V031A
3V
L
VDS
Quad
CMOS
Differential
Line
Driver
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
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