DS90LV048A
3V LVDS Quad CMOS Differential Line Receiver

General Description

The DS90LV048A is a quad CMOS flow-through differential
line receiver designed for applications requiring ultra low
power dissipation and high data rates. The device is de-
signed to support data rates in excess of 400 Mbps (200
MHz) utilizing Low Voltage Differential Signaling (LVDS)
technology.

The DS90LV048A accepts low voltage (350 mV typical) dif-
ferential input signals and translates them to 3V CMOS out-
put levels. The receiver supports a TRI-STATE

function that

may be used to multiplex outputs. The receiver also supports
open, shorted and terminated (100

) input fail-safe. The re-

ceiver output will be HIGH for all fail-safe conditions. The
DS90LV048A has a flow-through pinout for easy PCB layout.

The EN and EN

inputs are ANDed together and control the

TRI-STATE outputs. The enables are common to all four re-
ceivers. The DS90LV048A and companion LVDS line driver
(eg. DS90LV047A) provide a new alternative to high power
PECL/ECL devices for high speed point-to-point interface
applications.

Features

400 Mbps (200 MHz) switching rates

Flow-through pinout simplifies PCB layout

150 ps channel-to-channel skew (typical)

100 ps differential skew (typical)

2.7 ns maximum propagation delay

3.3V power supply design

High impedance LVDS inputs on power down

Low Power design (40mW 3.3V static)

Interoperable with existing 5V LVDS drivers

Accepts small swing (350 mV typical) differential signal
levels

Supports open, short and terminated input fail-safe

Conforms to ANSI/TIA/EIA-644 Standard

Industrial temperature operating range (-40°C to +85°C)

Available in SOIC and TSSOP package

Connection Diagram

Functional Diagram

ENABLES

INPUTS

OUTPUT

EN*

IN+

- R

IN-

OUT

L or Open

0.1V

-0.1V

Full Fail-safe

OPEN/SHORT

or Terminated

All other combinations of ENABLE inputs

TRI-STATE

is a registered trademark of National Semiconductor Corporation.

Dual-in-Line

DS100888-1

Order Number DS90LV048ATM, DS90LV048ATMTC

See NS Package Number M16A, MTC16

DS100888-2

July 1999

DS90L

V048A

VDS

Quad

CMOS

Differential

Line

Receiver

Š 1999 National Semiconductor Corporation

DS100888

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

)

-0.3V to +4V

Input Voltage (R

IN+

, R

IN-

)

-0.3V to 3.9V

Enable Input Voltage (EN, EN*)

-0.3V to (V

+ 0.3V)

Output Voltage (R

OUT

)

-0.3V to (V

+ 0.3V)

Maximum Package Power Dissipation +25°C

M Package

1025 mW

MTC Package

866 mW

Derate M Package

8.2 mW/°C above +25°C

Derate MTC Package

6.9 mW/°C above +25°C

Storage Temperature Range

-65°C to +150°C

Lead Temperature Range Soldering

(4 sec.)

+260°C

Maximum Junction Temperature

+150°C

ESD Rating (Note 10)

(HBM, 1.5 k

, 100 pF)

10 kV

(EIAJ, 0

, 200 pF)

1200 V

Recommended Operating
Conditions

Min

Typ

Max

Units

Supply Voltage (V

)

+3.0

+3.3

+3.6

Receiver Input Voltage

GND

+3.0

Operating Free Air

Temperature (T

)

-40

+85

°C

Electrical Characteristics

Over Supply Voltage and Operating Temperature ranges, unless otherwise specified. (Notes 2, 3)

Symbol

Parameter

Conditions

Pin

Min

Typ

Max

Units

Differential Input High Threshold

= +1.2V, 0.05V, 2.95V (Note 13)

IN+

+100

Differential Input Low Threshold

IN-

-100

VCMR

Common-Mode Voltage Range

VID = 200mV pk to pk (Note 5)

0.1

2.3

Input Current

= +2.8V

= 3.6V or 0V

-10

+10

ľA

= 0V

-10

+10

ľA

= +3.6V

= 0V

-20

+20

ľA

Output High Voltage

= -0.4 mA, V

= +200 mV

OUT

2.7

3.3

= -0.4 mA, Input terminated

2.7

3.3

= -0.4 mA, Input shorted

2.7

3.3

Output Low Voltage

= 2 mA, V

= -200 mV

0.05

0.25

Output Short Circuit Current

Enabled, V

OUT

= 0V (Note 11)

-15

-47

-100

Output TRI-STATE Current

Disabled, V

OUT

= 0V or V

-10

+10

ľA

Input High Voltage

EN,

EN*

2.0

Input Low Voltage

GND

0.8

Input Current

= 0V or V

, Other Input = V

GND

-10

+10

ľA

Input Clamp Voltage

= -18 mA

-1.5

-0.8

No Load Supply Current
Receivers Enabled

EN = V

, Inputs Open

CCZ

No Load Supply Current

EN = GND, Inputs Open

Receivers Disabled

Switching Characteristics

Over Supply Voltage and Operating Temperature ranges, unless otherwise specified. (Notes 3, 4, 7, 8)

Symbol

Parameter

Conditions

Min

Typ

Max

Units

PHLD

Differential Propagation Delay High to Low

= 15 pF

1.2

2.0

2.7

PLHD

Differential Propagation Delay Low to High

= 200 mV

1.2

1.9

2.7

SKD1

Differential Pulse Skew |t

PHLD

- t

PLHD

| (Note 6)

(

Figure 1 and Figure 2)

0.1

0.4

SKD2

Differential Channel-to-Channel Skew; same device
(Note 7)

0.15

0.5

SKD3

Differential Part to Part Skew (Note 8)

1.0

SKD4

Differential Part to Part Skew (Note 9)

1.5

TLH

Rise Time

0.5

1.0

THL

Fall Time

0.35

1.0

www.national.com

Switching Characteristics

(Continued)

Over Supply Voltage and Operating Temperature ranges, unless otherwise specified. (Notes 3, 4, 7, 8)

Symbol

Parameter

Conditions

Min

Typ

Max

Units

PHZ

Disable Time High to Z

= 2 k

PLZ

Disable Time Low to Z

= 15 pF

PZH

Enable Time Z to High

(

Figure 3 and Figure 4)

PZL

Enable Time Z to Low

MAX

Maximum Operating Frequency (Note 14)

All Channels Switching

200

250

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 unless otherwise speci-
fied.

Note 3: All typicals are given for: V

= +3.3V, T

= +25°C.

Note 4: Generator waveform for all tests unless otherwise specified: f = 1 MHz, Z

= 50

, t

and t

(0% to 100%)

3 ns for R

Note 5: The VCMR range is reduced for larger VID. Example: if VID = 400mV, the VCMR is 0.2V to 2.2V. The fail-safe condition with inputs shorted is not supported
over the common-mode range of 0V to 2.4V, but is supported only with inputs shorted and no external common-mode voltage applied. A VID up to V

- 0V may be

applied to the R

IN+

/ R

IN-

inputs with the Common-Mode voltage set to V

/2. Propagation delay and Differential Pulse skew decrease when VID is increased from

200mV to 400mV. Skew specifications apply for 200mV

VID

800mV over the common-mode range .

Note 6: t

SKD1

is the magnitude difference in differential propagation delay time between the positive going edge and the negative going edge of the same channel

Note 7: t

SKD2

, Channel-to-Channel Skew is defined as the difference between the propagation delay of one channel and that of the others on the same chip with

any event on the inputs.

Note 8: t

SKD3

, part to part skew, is the differential channel-to-channel skew of any event between devices. This specification applies to devices at the same V

and within 5°C of each other within the operating temperature range.

Note 9: 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 10: ESD Rating:HBM (1.5 k

, 100 pF)

10kV

EIAJ (0

, 200 pF)

1200V

Note 11: Output short circuit current (I

) is specified as magnitude only, minus sign indicates direction only. Only one output should be shorted at a time, do not

exceed maximum junction temperature specification.

Note 12: C

includes probe and jig capacitance.

Note 13: V

is always higher than R

IN+

and R

IN-

voltage. R

IN-

and R

IN+

are allowed to have a voltage range -0.2V to V

- VID/2. However, to be compliant with

AC specifications, the common voltage range is 0.1V to 2.3V

Note 14: f

MAX

generator input conditions: t

= t

1 ns (0% to 100%), 50% duty cycle, differential (1.05V to 1.35V peak to peak). Output criteria: 60/40% duty cycle,

(max 0.4V), V

(min 2.7V), Load = 15 pF (stray plus probes).

Parameter Measurement Information

DS100888-3

FIGURE 1. Receiver Propagation Delay and Transition Time Test Circuit

DS100888-4

FIGURE 2. Receiver Propagation Delay and Transition Time Waveforms

www.national.com

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,
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 5. This configuration provides a clean signaling en-

vironment for the fast 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

100

(selected to match the media), and is located as close

to the receiver input pins as possible. The termination resis-
tor converts the driver output (current mode) into a voltage
that is detected by the receiver. Other configurations are
possible such as a multi-receiver configuration, but the ef-
fects 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.

DS100888-5

includes load and test jig capacitance.

= V

for t

PZL

and t

PLZ

measurements.

= GND for t

PZH

and t

PHZ

measurements.

FIGURE 3. Receiver TRI-STATE Delay Test Circuit

DS100888-6

FIGURE 4. Receiver TRI-STATE Delay Waveforms

Balanced System

DS100888-7

FIGURE 5. Point-to-Point Application

www.national.com

Applications Information

(Continued)

The DS90LV048A differential line receiver is capable of de-
tecting signals as low as 100mV, over a

1V common-mode

range centered around +1.2V. This is related to the driver off-
set voltage which is typically +1.2V. The driven signal is cen-
tered around this voltage and may shift

1V around this cen-

ter 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 ef-
fects of coupled noise, or a combination of the two. The AC
parameters of both receiver input pins are optimized for a
recommended operating input voltage range of 0V to +2.4V
(measured from each pin to ground). The device will operate
for receiver input voltages up to V

, but exceeding V

will

turn on the ESD protection circuitry which will clamp the bus
voltages.

The DS90LV048A has a flow-through pinout that allows for
easy PCB layout. The LVDS signals on one side of the de-
vice easily allows for matching electrical lengths of the differ-
ential pair trace lines between the driver and the receiver as
well as allowing the trace lines to be close together to couple
noise as common-mode. Noise isolation is achieved with the
LVDS signals on one side of the device and the TTL signals
on the other side.

Power Decoupling Recommendations:

Bypass capacitors must be used on power pins. Use high
frequency ceramic (surface mount is recommended) 0.1ľF
and 0.001ľF capacitors in parallel at the power supply pin
with the smallest value capacitor closest to the device supply
pin. Additional scattered capacitors over the printed circuit
board will improve decoupling. Multiple vias should be used
to connect the decoupling capacitors to the power planes. A
10ľF (35V) or greater solid tantalum capacitor should be
connected at the power entry point on the printed circuit
board between the supply and ground.

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. In addition, noise induced on the differential lines is
much more likely to appear as common-mode which is re-
jected 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 termination resistor which best matches the differen-
tial 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 voltage. LVDS will not work without resistor termi-
nation. Typically, connecting a single resistor across the pair
at the receiver end will suffice.

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 (

2 pF) scope probes with a wide bandwidth (1

GHz) 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 effectively. For distances 0.5M

10M, CAT 3 (cat-

egory 3) twisted pair cable works well, is readily available
and relatively 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.

Open Input Pins. The DS90LV048A 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.

www.national.com

Applications Information

(Continued)

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.

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

2, 3, 6, 7

IN+

Non-inverting receiver input pin

1, 4, 5, 8

IN-

Inverting receiver input pin

10, 11, 14,

OUT

Receiver output pin

Receiver enable pin: When EN is
low, the receiver is disabled.
When EN is high and EN* is low
or open, the receiver is enabled.
If both EN and EN* are open
circuit, then the receiver is
disabled.

EN*

Receiver enable pin: When EN*
is high, the receiver is disabled.
When EN* is low or open and
EN is high, the receiver is
enabled. If both EN and EN* are
open circuit, then the receiver is
disabled.

Power supply pin, +3.3V

0.3V

GND

Ground pin

Ordering Information

Operating

Package Type/

Order Number

Temperature

Number

-40°C to +85°C

SOP/M16A

DS90LV048ATM

-40°C to +85°C

TSSOP/MTC16

DS90LV048ATMTC

Typical Performance Curves

Output High Voltage vs
Power Supply Voltage

DS100888-12

Output Low Voltage vs
Power Supply Voltage

DS100888-13

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Physical Dimensions

inches (millimeters) unless otherwise noted (Continued)

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whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.

2. A critical component is any component of a life

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 (0.100" Wide) Molded Thin Shrink Small Outline Package, JEDEC

Order Number DS90LV048ATMTC

NS Package Number MTC16

DS90L

V048A

VDS

Quad

CMOS

Differential

Line

Receiver

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.

Part Number DS90LV048A