SN65LVDS348 , SN65LVDT348
SN65LVDS352, SN65LVDT352
www.ti.com
SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
QUAD HIGH-SPEED DIFFERENTIAL RECEIVERS
FEATURES
•
•
•
•
•
•
DESCRIPTION
Meets or Exceeds the Requirements of ANSI
TIA/EIA-644A Standard
Single-Channel Signaling Rates up to
560 Mbps
-4 V to 5 V Common-Mode Input Voltage
Range
Flow-Through Architecture
Active Failsafe Assures a High-level Output
When an Input Signal Is not Present
SN65LVDS348 Provides a Wide CommonMode Range Replacement for the
SN65LVDS048A or the DS90LV048A
APPLICATIONS
•
•
•
•
•
Logic Level Translator
Point-to-Point Baseband Data Transmission
Over 100-Ω Media
ECL/PECL-to-LVTTL Conversion
Wireless Base Stations
Central Office or PABX Switches
The
SN65LVDS348,
SN65LVDT348,
SN65LVDS352, and SN65LVDT352 are high-speed,
quadruple differential receivers with a wide
common-mode input voltage range. This allows
receipt of TIA/EIA-644 signals with up to 3-V of
ground noise or a variety of differential and
single-ended logic levels. The '348 is in a 16-pin
package to match the industry-standard footprint of
the DS90LV048. The '352 adds two additional VCC
and GND pins in a 24-pin package to provide higher
data transfer rates with multiple receivers in
operation. All offer a flow-through architecture with all
inputs on one side and outputs on the other to ease
board layout and reduce crosstalk between
receivers. LVDT versions of both integrate a 110-Ω
line termination resistor.
These receivers also provide 3x the standard's
minimum common-mode noise voltage tolerance.
The -4 V to 5 V common-mode range allows usage
in harsh operating environments or accepts LVPECL,
PECL, LVECL, ECL, CMOS, and LVCMOS levels
without level shifting circuitry. See the Application
Information Section for more details on the
ECL/PECL to LVDS interface.
DATA TRANSFER RATE
vs
FREE-AIR TEMPERATURE
550
Timer
SN65LVDS352PW
LVDT Device
Only
Data Transfer Rate - Mxfr/s
500
450
400
SN65LVDS348PW
350
(One of Four Shown)
300
250
200
-60
215 -1 prbs NRZ, VID = 0.4 V
VIC = 1.2 V, CL = 5.5 pF, 40% Open Eye
4 Receivers Switching, Input Jitter < 45 ps
-40
-20
0
20
40
60
TA - Free-Air Temperature - °C
80
100
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2002–2004, Texas Instruments Incorporated
SN65LVDS348 , SN65LVDT348
SN65LVDS352, SN65LVDT352
www.ti.com
SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
DESCRIPTION (CONTINUED)
Precise control of the differential input voltage thresholds allows for inclusion of 50 mV of input-voltage
hysteresis to improve noise rejection. The differential input thresholds are still no more than ±50 mV over the full
input common-mode voltage range.
The receiver inputs can withstand ±15 kV human-body model (HBM), with respect to ground, without damage.
This provides reliability in cabled and other connections where potentially damaging noise is always a threat.
The receivers also include a (patent-pending) failsafe circuit that provides a high-level output approximately 600
ns after loss of the input signal. The most common causes of signal loss are disconnected cables, shorted lines,
or powered-down transmitters. This prevents noise from being received as valid data under these fault
conditions. This feature may also be used for Wired-Or bus signaling.
The SN65LVDT348 and SN65LVDT352 include an integrated termination resistor. This reduces board space
requirements and parts count by eliminating the need for a separate termination resistor. This can also improve
signal integrity at the receiver by reducing the stub length from the line termination to the receiver.
The intended application of these devices and signaling technique is for point-to-point baseband data
transmission over controlled impedance media of approximately 100 Ω. The transmission media may be
printed-circuit board traces, backplanes, or cables. The ultimate rate and distance of data transfer is dependent
upon the attenuation characteristics of the media and the noise coupling to the environment.
The SN65LVDS348, SN65LVDT348, SN65LVDS352 and SN65LVDT352 are characterized for operation from
-40°C to 85°C.
SN65LVDS348, SN65LVDT348
D or PW PACKAGE
(TOP VIEW)
RIN1–
RIN1+
RIN2+
RIN2–
RIN3–
RIN3+
RIN4+
RIN4–
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
SN65LVDS352, SN65LVDT352
PW PACKAGE
(TOP VIEW)
EN
ROUT1
ROUT2
VCC
GND
ROUT3
ROUT4
EN
1A
1B
2A
2B
EN 1,2
VCCA
AGND
EN 3,4
3A
3B
4A
4B
1
2
3
4
5
6
7
8
9
10
11
12
NC – No internal connection
2
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24
23
22
21
20
19
18
17
16
15
14
13
NC
1Y
DGND1
VCCD1
2Y
NC
NC
3Y
VCCD2
DGND2
4Y
NC
SN65LVDS348 , SN65LVDT348
SN65LVDS352, SN65LVDT352
www.ti.com
SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
FUNCTIONAL BLOCK DIAGRAMS (one of four receivers shown)
To Three Other Receivers
348 Devices
To One Other Receiver
352 Devices
EN
EN
EN
A
RIN+
ROUT1
Y
RIN–
B
Timer
Timer
SN65LVDT348
Only
SN65LVDT352
Only
Window Comparator
Window Comparator
AVAILABLE OPTIONS
PART NUMBER (1)
INTEGRATED TERMINATION
PACKAGE TYPE
PACKAGE MARKING
SOIC
LVDS348
SOIC
LVDT348
SN65LVDS348D
√
SN65LVDT348D
SN65LVDS348PW
√
SN65LVDT348PW
SN65LVDS352PW
√
SN65LVDT352PW
(1)
TSSOP
DL348
TSSOP
DE348
TSSOP
DL352
TSSOP
DE352
Add the R suffix to the device type (e.g., SN65LVDS348DR) for taped and reeled carrier.
FUNCTION TABLES
348 DEVICES
INPUTS
OUTPUTS
VID = VRIN+ - VRIN-
EN
EN
ROUT
VID≥ -32 mV
H
L or OPEN
H
100 mV < VID < -32 mV
H
L or OPEN
?
VID≤ -100 mV
H
L or OPEN
L
Open
H
L or OPEN
H
L or OPEN
X
Z
X
H
Z
X
352 DEVICES
INPUTS
OUTPUTS
VID = VIA - VIB
EN
Y
VID ≥ -32 mV
H
H
100 mV < VID < -32 mV
H
?
VID ≤ -100 mV
H
L
X
L or OPEN
Z
Open
H
H
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
EQUIVALENT INPUT AND OUTPUT SCHEMATIC DIAGRAMS
VCC
VCC
1 pF
6.5 kΩ
60 kΩ
Attenuation
Network
RIN+, A
250 kΩ
RIN–, B
7V
7V
7V
110 Ω
’LVDT Only
Attenuation
Network
VCC
VCC
100 Ω
37 Ω
EN, EN
ROUT, Y
7V
4
Attenuation
Network
7V
200 kΩ
3 pF
6.5 kΩ
7V
300 kΩ
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted) (1)
UNIT
Supply voltage range (2), VCC,VCCA,VCCD1, and VCCD2
-0.5 V TO 4 V
Enables, ROUT, or Y
Voltage range
-0.5 V to 6 V
Differential input magnitude MVIDM (LVDT only)
1V
RIN+, RIN-, A or B
-5 V to 6 V
Human body model (3)
A, B, RIN+, RIN- and GND
Electrostatic discharge
Charged-device model (4)
±15 kV
All pins
±7 kV
All pins
±500 V
Continuous power dissipation
See Dissipation Rating Table
Storage temperature range
(1)
(2)
(3)
(4)
-65°C to 150°C
Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating
conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltage values, except differential I/O bus voltages, are with respect to network ground terminal (GND, AGND).
Tested in accordance with JEDEC Standard 22, Test Method A114-A.
Tested in accordance with JEDEC Standard 22, Test Method C101.
DISSIPATION RATING TABLE
(1)
PACKAGE
TA ≤ 25°C
POWER RATING
OPERATING FACTOR (1)
ABOVE TA = 25°C
TA = 85°C
POWER RATING
D16
950 mW
7.6 mW/°C
494 mW
PW16
774 mW
6.2 mW/°C
402 mW
PW24
1087 mW
8.7 mW/°C
565 mW
This is the inverse of the junction-to-ambient thermal resistance when board-mounted and with no air
flow.
RECOMMENDED OPERATING CONDITIONS
MIN
NOM
MAX
UNIT
3
3.3
3.6
V
2
5
V
V
VCC,VCCA,VCCD1,
and VCCD2
Supply voltage
VIH
High-level input voltage
Enables
VIL
Low-level input voltage
Enables
0
0.8
Magnitude of differential
input voltage
|VID| (LVDT348, 352)
0.1
0.8
|VID| (LVDS348, 352)
0.1
3
-4
5
V
-40
85
°C
Input voltage (any combination of common mode or input signals)
TA
Operating free-air temperature
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V
5
SN65LVDS348 , SN65LVDT348
SN65LVDS352, SN65LVDT352
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
ELECTRICAL CHARACTERISTICS
over recommended operating conditions (unless otherwise noted)
PARAMETER
VITH1
TEST CONDITIONS
Positive-going differential input voltage
threshold
VITH3
Differential input failsafe voltage threshold
VID(HY
S)
Differential input voltage hysteresis,
VITH1 - VITH2
VOH
High-level output voltage
IOH = -4 mA
VOL
Low-level output voltage
IOL = 4 mA
See Figure 1 and Table 1
-32
2.4
V
0.4
Enabled, EN at VCC,
16
20
Disabled, EN at 0 or EN at VCC
1.1
4
LVDS352,
LVDT352
Enabled, EN at VCC,
16
20
1.1
4
Input current (RIN+, RIN-, A or B
inputs)
LVDS348,
LVDS352
Power-off input current (RIN+,
RIN-, A or B inputs)
LVDT348,
LVDT352
EN at 0 V, No load
No load
Disabled, EN at 0
mV
mV
LVDS348,
LVDT348
LVDT348,
LVDT352
V
mA
mA
VI = -4 V,
Other input open
-75
0 V ≤ VI ≤ 2.4 V,
Other input 1.2 V
-20
0
VI = 5 V,
Other input open
0
40
VI = -4 V,
Other input open
-150
0
0 V ≤ VI ≤ 2.4 V,
Other input open
-40
0
VI = 5 V,
Other input open
0
80
VCC = 1.5 V, VI = -4 V or 5 V, Other input open
-50
50
VCC = 1.5 V, 0 V ≤ VI≤ 2.4 V, Other input
at 1.2 V
-20
20
-100
100
-40
40
4
µA
132
Ω
0
10
µA
0
10
µA
-10
10
µA
VCC = 1.5 V, VI = -4 V or 5 V, Other input open
VCC = 1.5 V, VI = 0 V or 2.4 V, Other input
open
IID
Differential input current
(IRIN+ - IRIN-, or IIA - IIB)
LVDS348,
LVDS352
VID = 100 mV,
VIC = -3.9 V or 4.9 V
-4
RT
Differential input resistance
LVDT348,
LVDT352
VCC = 0 V, VID = 250 mV, VI = 0 V or 2.4 V
90
IIH
High-level input current
Enables
VIH = 2 V
IIL
Low-level input current
Enables
VIL = 0.8 V
IOZ
High-impedance output current
CIN
Input capacitance, RIN+, RIN- input to GND or A
VI = 0.4 sin (4E6πft) + 0.5 V
or B input to AGND
(1)
-100
50
LVDS348,
LVDS352
6
mV
-50
Supply current
II(OFF)
UNIT
50
Negative-going differential input voltage
threshold
II
TYP (1) MAX
See Figure 1 and Figure 2
VITH2
ICC
MIN
VO = 0 V
All typical values are at 25°C and with a 3.3-V supply.
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0
111
5
µA
µA
µA
µA
pF
SN65LVDS348 , SN65LVDT348
SN65LVDS352, SN65LVDT352
www.ti.com
SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
SWITCHING CHARACTERISTICS
over recommended operating conditions (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP (1)
MAX
UNIT
tPLH
Propagation delay time, low-to-high-level output
2.5
4
6
ns
tPHL
Propagation delay time, high-to-low-level output
2.5
4
6
ns
td1
Delay time, failsafe disable time
td2
Delay time, failsafe enable time
tsk(p)
Pulse skew (|tpHL1 - tpLH1|)
0.3
CL = 10 pF, See Figure 3
Output
tsk(pp)
Part-to-part skew (3)
tr
Output signal rise time
tf
Output signal fall time
tr
Output signal rise time
tf
Output signal fall time
tPHZ
Propagation delay time, high-level-to-high-impedance output
tPLZ
Propagation delay time, low-level-to-high-impedance output
tPZH
Propagation delay time, high-impedance-to-high-level output
tPZL
Propagation delay time, high-impedance-to-low-level output
(1)
(2)
(3)
ns
µs
200
skew (2)
tsk(o)
12
1.5
ps
150
ps
1
CL = 1 pF, See Figure 3
ns
1
ns
650
ps
400
5
See Figure 4 and Figure 5
ns
1.2
ps
9
ns
5
9
ns
8
12
ns
8
12
ns
All typical values are at 25°C and with a 3.3-V supply.
tsk(o) is the magnitude of the time difference between the tPHL or tPLH of all receivers of a single device with all of their inputs connected
together.
tsk(pp) is the magnitude of the difference in propagation delay times between any specified terminals of two devices when both devices
operate with the same supply voltages, at the same temperature, and have identical packages and test circuits.
PARAMETER MEASUREMENT INFORMATION
IIA or IRIN+
A or RIN+
Y or ROUT
VID
(VIA + VIB)/2 or
(VRIN+ + VRIN–)/2
VIA or VRIN+
VIC
B or RIN–
IIB or IRIN–
VIB or VRIN–
IOY or IROUT
VOY or VROUT
Figure 1. Voltage and Current Definitions
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
PARAMETER MEASUREMENT INFORMATION (continued)
1000 Ω
100 Ω
+
1000 Ω
100 Ω†
VID
+
V1
V2
VO
–
–
10 pF
VIC
10 pF
10 pF
+
–
A.
Remove for testing LVDT device.
B.
Input signal of 3 MHz, duty cycle of 50±0.2%, and transition time of < 1ns.
C.
Fixture capacitance ±20%.
D.
Resistors are metal film, 1% tolerance, and surface mount
VITH1
0V
VID
–100 mV
VO
100 mV
VID
0V
VITH2
VO
Figure 2. VITH1 and VITH2, Input Voltage Threshold Test Circuit and Definitions
Table 1. Receiver Minimum and Maximum Failsafe Input Voltage
FAILSAFE THRESHOLD TEST VOLTAGES
APPLIED VOLTAGES (1)
(1)
8
RESULTANT INPUTS
Output
VIA (mV)
VIB (mV)
VID (mV)
VIC (mV)
-4000
-3900
-100
-3950
L
-4000
-3968
-32
-3984
H
4900
5000
-100
4950
L
4968
5000
-32
4984
H
Voltage applied for greater than 1.5 µs.
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
A or RIN+
Y or ROUT
VID
VIA or VRIN+
B or RIN–
CL
VOY or VROUT
VIB or VRIN–
A or VRIN+
1.4 V
B or VRIN–
1V
>1.5 µs
0.4 V
VID
0V
–0.2 V
–0.4 V
tPHL
tPLH
td1
td2
VOH
VOY or VROUT
VCC/2
VOL
tf
A.
tr
All input pulses are supplied by a generator having the following characteristics: tr or tf ≤ 1 ns, signaling rate = 250
kHz, duty cycle = 50 ±2%, CL includes instrumentation and fixture capacitance within 0,06 mm of the D.U.T and is
±20%.
Figure 3. Timing Test Circuit and Waveforms
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
1.2 V
RIN–
500 Ω
ROUT
RIN+
Inputs
EN
VROUT
+
_
VTEST
10 pF
EN
VTEST
2.5 V
VRIN+
1V
2V
1.4 V
0.8 V
2V
1.4 V
0.8 V
EN
EN
tPZL
tPZL
tPLZ
tPLZ
2.5 V
1.4 V
VOL +0.5 V
VOL
VROUT
VTEST
0V
1.4 V
VRIN+
2V
1.4 V
0.8 V
2V
1.4 V
0.8 V
EN
EN
tPZH
tPZH
VOH
VOH –0.5 V
1.4 V
0V
VROUT
A.
tPHZ
tPHZ
All input pulses are supplied by a generator having the following characteristics: tr or tf ≤ 1 ns, signaling rate = 500
kHz, duty cycle = 50 ±2%, CL includes instrumentation and fixture capacitance within 0,06 mm of the D.U.T and is
±20%.
Figure 4. 348 Enable/Disable Time Test Circuit and Waveforms
10
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
B
1.2 V
500 Ω
Y
A
Inputs
EN
VO
+
_
VTEST
10 pF
2.5 V
VTEST
A
1V
2V
1.4 V
0.8 V
EN
tPZL
tPLZ
2.5 V
1.4 V
VOL +0.5 V
VOL
VO
VTEST
A
0V
1.4 V
EN
2V
1.4 V
0.8 V
tPZH
tPHZ
VOH
VOH –0.5 V
1.4 V
0V
VO
A.
All input pulses are supplied by a generator having the following characteristics: tr or tf ≤ 1 ns, signaling rate = 500
kHz, duty cycle = 50 ±2 %, CL includes instrumentation and fixture capacitance within 0,06 mm of the D.U.T and is
±20%.
Figure 5. 352 Enable/Disable Time Test Circuit and Waveforms
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
TYPICAL CHARACTERISTICS
LOW-TO-HIGH PROPAGATION DELAY
vs
FREE-AIR TEMPERATURE
HIGH-TO-LOWPROPAGATION DELAY
vs
FREE-AIR TEMPERATURE
5
5
See NO TAG
4.5
t PHL - High-to-Low Propagation Delay - ns
t PLH - Low-to-High Propagation Delay - ns
See NO TAG
VCC = 3 V
VCC = 3.3 V
4
VCC = 3.6 V
3.5
3
-50
0
50
VCC = 3 V
4.5
VCC = 3.3 V
4
VCC = 3.6 V
3.5
3
-50
100
TA - Free-Air Temperature - °C
0
50
TA - Free-Air Temperature - °C
Figure 6.
Figure 7.
LOW-LEVEL OUTPUT CURRENT
vs
LOW-LEVEL OUTPUT VOLTAGE
HIGH-LEVEL OUTPUT CURRENT
vs
HIGH-LEVEL OUTPUT VOLTAGE
0
40
TA = 25°C,
VCC = 3.3 V
12
I OH - High-Level Output Current - mA
I OL - Low-Level Output Current - mA
TA = 25°C,
VCC = 3.3 V
30
20
10
0
100
-10
-20
-30
-40
0
VOL - Low-Level Output Voltage - V
1
2
3
VOH - High-Level Output Voltage - V
Figure 8.
Figure 9.
1
2
3
4
5
0
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
TYPICAL CHARACTERISTICS (continued)
DATA TRANSFER RATE
vs
FREE-AIR TEMPERATURE
RMS SUPPLY CURRENT
vs
SWITCHING FREQUENCY
500
110
Maximum Transfer Rate - Mxfr/s
450
400
I CC - RMS Supply Current - mA
215 -1 prbs NRZ,
VIC = 1.2 V,
CL = 5.5 pF,
40% Open Eye,
4 Receivers Switching,
VCC = 3.3 V,
SN65LVDS348PW
VID = 0.4 V
350
300
VID = 0.1 V
VID = 0.2 V
4 Receivers Switching,
50% Duty Cycle,
CL = 5.5 pF,
TA = 25°C
90
VCC = 3.6 V
VCC = 3.3 V
70
VCC = 3 V
50
30
250
200
-60
10
-40
-20
0
20
40
60
80
100
0
50
100
150
200
TA - Free-Air Temperature - °C
f - Switching Frequency - MHz
Figure 10.
Figure 11.
223 -1 prbs NRZ, TA = 25°C, CL = 5.5 pF,
4 Receivers Switching, VCC = 3.3 V
250
300
223 -1 prbs NRZ, TA = 25°C, CL = 5.5 pF,
4 Receivers Switching, VCC = 3.3 V
Figure 12. SN65LVDS348 Eye
Pattern Running at 200 Mxfr/s
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Figure 13. SN65LVDS352 Eye
Pattern Running at 200 Mxfr/s
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
APPLICATION INFORMATION
IMPEDANCE MATCHING AND REFLECTIONS
A termination mismatch can result in reflections that degrade the signal at the load. A low source impedance
causes the signal to alternate polarity at the load (oscillates) as shown in Figure 14. High source impedance
results in the signal accumulating monotonically to the final value (stair step) as shown in Figure 15. Both of
these modes result in a delay in valid signal and reduce the opening in the eye pattern. A 10% termination
mismatch results in a 5% reflection (r = ZL - ZO/ZL + ZO), even a 1:3 mismatch absorbs half of the incoming
signal. This shows that termination is important in the more critical cases, however, in a general sense, a rather
large termination mismatch is not as critical when the differential output signal is much greater than the receiver
sensitivity.
TIME DOMAIN RESPONSE
0.25
TIME DOMAIN RESPONSE
0.25
ZS = 0 Ω
ZO = 100 Ω
ZT = 132 Ω
V at Load
0.2
ZS = 0 Ω
ZO = 100 Ω
ZT = 90 Ω
0.2
V at Load
VI
0.15
Voltage - V
Voltage - V
VI
0.1
0.05
0.15
0.1
0.05
0
0
0
5
10
15
20
25
0
5
10
15
20
t - Time - ns
t - Time - ns
Figure 14. Low-Source Impedance
Figure 15. High-Source Impedance
25
For example a 200-mV drive signal into a 100-Ω lossless transmission media with a termination resistor of 90 Ω
to 132Ω results in ~227 mV to 189 mV into the receiver. This would typically be more than enough signal into a
receiver with a sensitivity of ±50 mV assuming no other disturbance or attenuation on the line. The other factors,
which reduce the signal margin, do affect this and therefore it is important to match the impedance as closely as
possible to allow more noise immunity at the receiver.
14
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SN65LVDS352, SN65LVDT352
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
APPLICATION INFORMATION (continued)
ACTIVE FAILSAFE FEATURE
A differential line receiver commonly has a failsafe circuit to prevent it from switching on input noise. Current
LVDS failsafe solutions require either external components with subsequent reductions in signal quality or
integrated solutions with limited application. This family of receivers has a new integrated failsafe that solves the
limitations seen in present solutions. A detailed theory of operation is presented in application note The Active
Fail-Safe in TI's LVDS Receivers, literature number SLLA082B.
The following figure shows one receiver channel with active failsafe. It consists of a main receiver that can
respond to a high-speed input differential signal. Also connected to the input pair are two failsafe receivers that
form a window comparator. The window comparator has a much slower response than the main receiver and it
detects when the input differential falls below 80 mV. A 600-ns failsafe timer filters the window comparator
outputs. When failsafe is asserted, the failsafe logic drives the main receiver output to logic high.
Output
Buffer
Main Receiver
A
B
+
_
R
Reset
Failsafe
Timer
A > B + 80 mV
+
_
Failsafe
B > A + 80 mV
+
_
Window Comparator
Figure 16. Receiver With Active Failsafe
ECL/PECL-to-LVTTL CONVERSION WITH TI's LVDS RECEIVER
The various versions of emitter-coupled logic (i.e., ECL, PECL and LVPECL) are often the physical layer of
choice for system designers. Designers know that established technology is capable of high-speed data
transmission. In the past, system requirements often forced the selection of ECL. Now technologies like LVDS
provide designers with another alternative. While the total exchange of ECL for LVDS may not be a design
option, designers have been able to take advantage of LVDS by implementing a small resistor divider network at
the input of the LVDS receiver. TI has taken the next step by introducing a wide common-mode LVDS receiver
(no divider network required) which can be connected directly to an ECL driver with only the termination bias
voltage required for ECL termination (VCC - 2 V).
Figure 17 shows the use of an LV/PECL driver driving 5 meters of CAT-5 cable and being received by TI's wide
common-mode receiver and the resulting eye-pattern. The values for R3 are required in order to provide a
resistor path to ground for the LV/PECL driver. With no resistor divider, R1 simply needs to match the
characteristic load impedance of 50 Ω. The R2 resistor is a small value intended to minimize common-mode
reflections.
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15
SN65LVDS348 , SN65LVDT348
SN65LVDS352, SN65LVDT352
www.ti.com
SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
APPLICATION INFORMATION (continued)
VCC
R1 = 50 Ω
R2 = 50 Ω
ICC
5 Meters
of CAT-5
LV/PECL
R3
VEE
R3
VB
VCC
ICC
LVDS
VB
R1
R1
R2
R3 = 240 Ω
Figure 17. LVPECL or PECL to Remote Wide Common-Mode LVDS Receiver
DEVICE POWER AND GROUNDING
The SN65LVDS352 device provides separate power and ground pins for the analog input section and the two
digital output sections. All of the power pins and all of the ground pins of the device must be tied together at
some point in the system. Figure 18 shows one recommended scheme for power and ground to the device. This
point will be determined by the power and grounding distribution design, which can greatly affect system
performance.
Key points to remember when routing power and grounds in your system are:
• The grounding system must provide a low impedance path back to the power source.
• The signal return must be close to the signal path.
• Ground noise occurs due to ground loops and common-mode noise pick-up.
• Closely spaced power and ground planes reduce inductance and increase capacitance.
A good rule to remember when doing your power distribution and board layout is that the current always flows in
the lowest impedance path. At dc the lowest resistance is the lowest impedance, but at high frequencies the
lowest impedance is the lowest inductance path.
16
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SN65LVDS352, SN65LVDT352
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SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
APPLICATION INFORMATION (continued)
VCC
VCCD1
Bypass
Capacitor†
DGND1
Bypass
Capacitor†
VCCA
AGND
VCCD2
Bypass
Capacitor†
DGND2
†
Bypass capacitors used for data sheet electrical testing were low ESR ceramic, surface mount, 0.01 µF ±10%. For a more accurate
determination of these values refer to the application note, The Bypass Capacitor in High-Speed Environments, literature number SCBA007A.
Figure 18. Recommended Power and Ground Connection
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17
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
SN65LVDS348D
ACTIVE
SOIC
D
16
40
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
LVDS348
SN65LVDS348PW
ACTIVE
TSSOP
PW
16
90
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
DL348
SN65LVDS348PWG4
ACTIVE
TSSOP
PW
16
90
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
DL348
SN65LVDS348PWR
ACTIVE
TSSOP
PW
16
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
DL348
SN65LVDS348PWRG4
ACTIVE
TSSOP
PW
16
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
DL348
SN65LVDS352PW
ACTIVE
TSSOP
PW
24
60
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
DL352
SN65LVDT348D
ACTIVE
SOIC
D
16
40
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
LVDT348
SN65LVDT348PW
ACTIVE
TSSOP
PW
16
90
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
DE348
SN65LVDT348PWG4
ACTIVE
TSSOP
PW
16
90
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
DE348
SN65LVDT348PWR
ACTIVE
TSSOP
PW
16
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
DE348
SN65LVDT348PWRG4
ACTIVE
TSSOP
PW
16
2000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 85
DE348
SN65LVDT352PW
ACTIVE
TSSOP
PW
24
60
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
DE352
SN65LVDT352PWR
ACTIVE
TSSOP
PW
24
2000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
DE352
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of