NSC SCAN15MB200TSQ

SCAN15MB200
Dual 1.5 Gbps 2:1/1:2 LVDS Mux/Buffer with
Pre-Emphasis and IEEE 1149.6
General Description
Features
The SCAN15MB200 is a dual-port 2 to 1 multiplexer and 1 to
2 repeater/buffer. High-speed data paths and flow-through
pinout minimize internal device jitter and simplify board layout, while pre-emphasis overcomes ISI jitter effects from
lossy backplanes and cables. The differential inputs and
outputs interface to LVDS or Bus LVDS signals such as
those on National’s 10-, 16-, and 18- bit Bus LVDS SerDes,
or to CML or LVPECL signals.
Integrated IEEE 1149.1 (JTAG) and 1149.6 circuitry supports
testability of both single-ended LVTTL/CMOS and highspeed differential PCB interconnects. The 3.3V supply,
CMOS process, and robust I/O ensure high performance at
low power over the entire industrial -40 to +85˚C temperature
range.
n 1.5 Gbps data rate per channel
n Configurable off/on pre-emphasis drives lossy
backplanes and cables
n LVDS/BLVDS/CML/LVPECL compatible inputs, LVDS
compatible outputs
n Low output skew and jitter
n On-chip 100Ω input and output termination
n IEEE 1149.1 and 1149.6 compliant
n 15 kV ESD protection on LVDS inputs/outputs
n Hot plug Protection
n Single 3.3V supply
n Industrial -40 to +85˚C temperature range
n 48-pin LLP Package
Typical Application
20132810
Block Diagram
20132801
FIGURE 1. SCAN15MB200 Block Diagram
© 2006 National Semiconductor Corporation
DS201328
www.national.com
SCAN15MB200 Dual 1.5 Gbps 2:1/1:2 LVDS Mux/Buffer with Pre-Emphasis and IEEE 1149.6
May 2006
SCAN15MB200
Pin Descriptions
Pin
Name
LLP Pin
Number
I/O, Type
Description
SWITCH SIDE DIFFERENTIAL INPUTS
SIA_0+
SIA_0−
30
29
I, LVDS
Switch A-side Channel 0 inverting and non-inverting differential inputs. LVDS, Bus LVDS,
CML, or LVPECL compatible.
SIA_1+
SIA_1−
19
20
I, LVDS
Switch A-side Channel 1 inverting and non-inverting differential inputs. LVDS, Bus LVDS,
CML, or LVPECL compatible.
SIB_0+
SIB_0−
28
27
I, LVDS
Switch B-side Channel 0 inverting and non-inverting differential inputs. LVDS, Bus LVDS,
CML, or LVPECL compatible.
SIB_1+
SIB_1−
21
22
I, LVDS
Switch B-side Channel 1 inverting and non-inverting differential inputs. LVDS, Bus LVDS,
CML, or LVPECL compatible.
LINE SIDE DIFFERENTIAL INPUTS
LI_0+
LI_0−
40
39
I, LVDS
Line-side Channel 0 inverting and non-inverting differential inputs. LVDS, Bus LVDS, CML, or
LVPECL compatible.
LI_1+
LI_1−
9
10
I, LVDS
Line-side Channel 1 inverting and non-inverting differential inputs. LVDS, Bus LVDS, CML, or
LVPECL compatible.
SWITCH SIDE DIFFERENTIAL OUTPUTS
SOA_0+
SOA_0−
34
33
O, LVDS Switch A-side Channel 0 inverting and non-inverting differential outputs. LVDS compatible
(Notes 1, 3).
SOA_1+
SOA_1−
15
16
O, LVDS Switch A-side Channel 1 inverting and non-inverting differential outputs. LVDS compatible
(Notes 1, 3).
SOB_0+
SOB_0−
32
31
O, LVDS Switch B-side Channel 0 inverting and non-inverting differential outputs. LVDS compatible
(Notes 1, 3).
SOB_1+
SOB_1−
17
18
O, LVDS Switch B-side Channel 1 inverting and non-inverting differential outputs. LVDS compatible
(Notes 1, 3).
LINE SIDE DIFFERENTIAL OUTPUTS
LO_0+
LO_0−
42
41
O, LVDS Line-side Channel 0 inverting and non-inverting differential outputs. LVDS compatible (Notes
1, 3).
LO_1+
LO_1−
7
8
O, LVDS Line-side Channel 1 inverting and non-inverting differential outputs. LVDS compatible (Notes
1, 3).
DIGITAL CONTROL INTERFACE
MUX_S0
MUX_S1
38
11
I, LVTTL
Mux Select Control Inputs (per channel) to select which Switch-side input, A or B, is passed
through to the Line-side.
PREA_0
PREA_1
PREB_0
PREB_1
26
23
25
24
I, LVTTL
Output pre-emphasis control for Switch-side outputs. Each output driver on the Switch A-side
and B-side has a separate pin to control the pre-emphasis on or off.
PREL_0
PREL_1
44
5
I, LVTTL
Output pre-emphasis control for Line-side outputs. Each output driver on the Line A-side and
B-side has a separate pin to control the pre-emphasis on or off.
ENA_0
ENA_1
ENB_0
ENB_1
36
13
35
14
I, LVTTL
Output Enable Control for Switch A-side and B-side outputs. Each output driver on the A-side
and B-side has a separate enable pin.
ENL_0
ENL_1
45
4
I, LVTTL
Output Enable Control for The Line-side outputs. Each output driver on the Line-side has a
separate enable pin.
TDI
2
I, LVTTL
Test Data Input to support IEEE 1149.1 features
TDO
1
O, LVTTL Test Data Output to support IEEE 1149.1 features
TMS
46
I, LVTTL
Test Mode Select to support IEEE 1149.1 features
TCK
47
I, LVTTL
Test Clock to support IEEE 1149.1 features
TRST
3
I, LVTTL
Test Reset to support IEEE 1149.1 features
POWER
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2
Pin
Name
LLP Pin
Number
SCAN15MB200
Pin Descriptions
(Continued)
I/O, Type
Description
VDD
6, 12, 37,
43, 48
I, Power
VDD = 3.3V ± 0.3V.
GND
(Note 2)
I, Power
Ground reference for LVDS and CMOS circuitry.
For the LLP package, the DAP is used as the primary GND connection to the device. The
DAP is the exposed metal contact at the bottom of the LLP-48 package. It should be
connected to the ground plane with at least 4 vias for optimal AC and thermal performance.
Note 1: For interfacing LVDS outputs to CML or LVPECL compatible inputs, refer to the applications section of this datasheet (planned).
Note 2: Note that the DAP on the backside of the LLP package is the primary GND connection for the device when using the LLP package.
Note 3: The LVDS outputs do not support a multidrop (BLVDS) environment. The LVDS output characteristics of the SCAN15MB200 device have been optimized
for point-to-point backplane and cable applications.
3
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SCAN15MB200
Connection Diagrams
20132802
LLP Top View
DAP = GND
20132803
Directional Signal Paths Top View
(Refer to pin names for signal polarity)
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4
Multiplexer Truth Table
The output characteristics of the SCAN15MB200 have been
optimized for point-to-point backplane and cable applications, and are not intended for multipoint or multidrop signaling.
A 100Ω output (source) termination resistor is incorporated
in the device to eliminate the need for an external resistor,
providing excellent drive characteristics by locating the
source termination as close to the output as physically possible.
Data Inputs
(Note 5)
Control Inputs
SIB_0
MUX_S0
ENL_0
LO_0
X
valid
0
1
SIB_0
valid
X
1
1
SIA_0
X
X
X
0 (Note 6)
Z
X = Don’t Care
Z = High Impedance (TRI-STATE)
Repeater/Buffer Truth Table
Pre-Emphasis Controls
Data
Input
The pre-emphasis is used to compensate for long or lossy
transmission media. Separate pins are provided for each
output to minimize power consumption. Pre-emphasis is
programmable to be off or on per the Pre-emphasis Control
Table.
PREx_n (Note 4)
Output Pre-emphasis
0
0%
1
100%
Output
SIA_0
Control Inputs
LI_0
ENA_0
ENB_0
(Note 5)
Outputs
SOA_0
SOB_0
X
0
0
valid
0
1
Z (Note 6) Z (Note 6)
Z
LI_0
valid
1
0
LI_0
Z
valid
1
1
LI_0
LI_0
X = Don’t Care
Z = High Impedance (TRI-STATE)
Note 4: Applies to PREA_0, PREA_1, PREB_0, PREB_1, PREL_0,
PREL_1
Note 5: Same functionality for channel 1
Note 6: When all enable inputs from both channels are Low, the device
enters a powerdown mode. Refer to the applications section titled TRI-STATE
and Powerdown modes.
5
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SCAN15MB200
Output Characteristics
SCAN15MB200
Absolute Maximum Ratings (Note 7)
Supply Voltage (VDD)
EIAJ, 0Ω, 200pF
CDM
−0.3V to +4.0V
CMOS Input Voltage
-0.3V to (VDD+0.3V)
LVDS Receiver Input Voltage
(Note 8)
-0.3V to (VDD+0.3V)
LVDS Driver Output Voltage
-0.3V to (VDD+0.3V)
LVDS Output Short Circuit Current
+40 mA
Junction Temperature
+150˚C
Storage Temperature
−65˚C to +150˚C
Lead Temperature (Solder, 4sec)
260˚C
Max Pkg Power Capacity @ 25˚C
5.2W
Thermal Resistance (θJA)
Package Derating above +25˚C
Supply Voltage (VCC)
8kV
15kV
3.0V to 3.6V
Input Voltage (VI) (Note 8)
0V to VCC
Output Voltage (VO)
0V to VCC
Operating Temperature (TA)
Industrial
−40˚C to +85˚C
Note 7: Absolute maximum ratings are those values beyond which damage
to the device may occur. The databook specifications should be met, without
exception, to ensure that the system design is reliable over its power supply,
temperature, and output/input loading variables. National does not recommend operation of products outside of recommended operation conditions.
41.7mW/˚C
LVDS pins to GND only
1000V
Recommended Operating
Conditions
24˚C/W
ESD Last Passing Voltage
HBM, 1.5kΩ, 100pF
250V
Note 8: VID max < 2.4V
Electrical Characteristics
Over recommended operating supply and temperature ranges unless other specified.
Symbol
Parameter
Conditions
Min
Typ
(Note 9)
Max
Units
LVTTL DC SPECIFICATIONS (MUX_Sn, PREA_n, PREB_n, PREL_n, ENA_n, ENB_n, ENL_n, TDI, TDO, TCK, TMS, TRST)
VIH
High Level Input Voltage
2.0
VDD
V
VIL
Low Level Input Voltage
GND
0.8
V
IIH
High Level Input Current
VIN = VDD = VDDMAX
−10
+10
µA
IIHR
High Level Output Current
PREA_n, PREB_n, PREL_n
40
200
µA
IIL
Low Level Input Current
VIN = VSS, VDD = VDDMAX
−10
+10
µA
-40
-200
µA
IILR
Low Level Input Current
TDI, TMS, TRST
CIN1
Input Capacitance
Any Digital Input Pin to VSS
2.0
pF
COUT1
Output Capacitance
Any Digital Output Pin to VSS
4.0
pF
VCL
Input Clamp Voltage
ICL = −18 mA
−0.8
V
VOH
High Level Output Voltage
(TDO)
IOH = −12 mA, VDD = 3.0 V
2.4
V
IOH = −100 µA, VDD = 3.0 V
VDD-0.2
V
−1.5
VOL
Low Level Output Voltage
(TDO)
IOL = 100 µA, VDD = 3.0 V
0.2
V
IOS
Output Short Circuit Current
TDO
-15
-125
mA
IOZ
Output TRI-STATE Current
TDO
-10
+10
µA
100
mV
IOL = 12 mA, VDD = 3.0 V
0.5
V
LVDS INPUT DC SPECIFICATIONS (SIA ± , SIB ± , LI ± )
VTH
Differential Input High Threshold
(Note 10)
VCM = 0.8V or 1.2V or 3.55V,
VDD = 3.6V
VTL
Differential Input Low Threshold
(Note 10)
VCM = 0.8V or 1.2V or 3.55V,
VDD = 3.6V
−100
VID
Differential Input Voltage
VCM = 0.8V to 3.55V, VDD = 3.6V
100
VCMR
Common Mode Voltage Range
VID = 150 mV, VDD = 3.6V
0.05
CIN2
Input Capacitance
IN+ or IN− to VSS
IIN
Input Current
VIN = 3.6V, VDD = VDDMAX or 0V
−15
+15
µA
VIN = 0V, VDD = VDDMAX or 0V
−15
+15
µA
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6
0
0
mV
2400
3.55
2.0
mV
V
pF
(Continued)
Over recommended operating supply and temperature ranges unless other specified.
Symbol
Parameter
Conditions
Min
Typ
(Note 9)
Max
Units
250
360
500
mV
35
mV
1.475
V
35
mV
-40
mA
LVDS OUTPUT DC SPECIFICATIONS (SOA_n ± , SOB_n ± , LO_n ± )
VOD
Differential Output Voltage,
0% Pre-emphasis (Note 10)
∆VOD
Change in VOD between
Complementary States
-35
RL is the internal 100Ω between OUT+
and OUT−
VOS
Offset Voltage (Note 11)
1.05
∆VOS
Change in VOS between
Complementary States
1.22
-35
IOS
Output Short Circuit Current
OUT+ or OUT− Short to GND
−21
COUT2
Output Capacitance
OUT+ or OUT− to GND when
TRI-STATE
4.0
All inputs and outputs enabled and
active, terminated with differential load
of 100Ω between OUT+ and OUT-.
225
275
mA
ENA_0 = ENB_0 = ENL_0= ENA_1 =
ENB_1 = ENL_1 = L
0.6
4.0
mA
170
250
ps
170
250
ps
1.0
2.5
ns
1.0
2.5
ns
pF
SUPPLY CURRENT (Static)
ICC
ICCZ
Supply Current
Supply Current - Powerdown
Mode
SWITCHING CHARACTERISTICS — LVDS OUTPUTS
tLHT
tHLT
Differential Low to High Transition Use an alternating 1 and 0 pattern at
Time
200 Mb/s, measure between 20% and
Differential High to Low Transition 80% of VOD. (Note 16)
Time
tPLHD
Differential Low to High
Propagation Delay
tPHLD
Differential High to Low
Propagation Delay
tSKD1
Pulse Skew
|tPLHD–tPHLD| (Note 16)
25
75
ps
tSKCC
Output Channel to Channel Skew
Difference in propagation delay (tPLHD
or tPHLD) among all output channels.
(Note 16)
50
115
ps
RJ - Alternating 1 and 0 at 750MHz
(Note 13)
1.1
1.5
psrms
DJ - K28.5 Pattern, 1.5 Gbps (Note 14)
20
34
psp-p
TJ - PRBS 27-1 Pattern, 1.5 Gbps (Note
15)
14
28
psp-p
Time from ENA_n, ENB_n, or ENL_n to
OUT ± change from TRI-STATE to
active.
0.5
1.5
µs
LVDS Output Enable time from
powerdown mode
Time from ENA_n, ENB_n, or ENL_n to
OUT ± change from Powerdown to
active
10
20
µs
LVDS Output Disable Time
Time from ENA_n, ENB_n, or ENL_n to
OUT ± change from active to
TRI-STATE or powerdown.
12
ns
tJIT
tON
tON2
tOFF
Jitter (0% Pre-emphasis)
(Note 12)
LVDS Output Enable Time
Use an alternating 1 and 0 pattern at
200 Mb/s, measure at 50% VOD
between input to output.
7
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SCAN15MB200
Electrical Characteristics
SCAN15MB200
Electrical Characteristics
(Continued)
Over recommended operating supply and temperature ranges unless other specified.
Symbol
Parameter
Typ
(Note 9)
Conditions
Min
Max
Units
RL = 500Ω,
CL = 35 pF
25.0
MHz
3.0
ns
SWITCHING CHARACTERISTICS - SCAN FEATURES
fMAX
Maximum TCK Clock Frequency
tS
TDI to TCK, H or L
tH
TDI to TCK, H or L
0.5
ns
tS
TMS to TCK, H or L
3.0
ns
tH
TMS to TCK, H or L
0.5
ns
tW
TCK Pulse Width, H or L
10.0
ns
tW
TRST Pulse Width, L
2.5
ns
tREC
Recovery Time, TRST to TCK
2.0
ns
Note 9: Typical parameters are measured at VDD = 3.3V, TA = 25˚C. They are for reference purposes, and are not production-tested.
Note 10: Differential output voltage VOD is defined as ABS(OUT+–OUT−). Differential input voltage VID is defined as ABS(IN+–IN−).
Note 11: Output offset voltage VOS is defined as the average of the LVDS single-ended output voltages at logic high and logic low states.
Note 12: Jitter is not production tested, but guaranteed through characterization on a sample basis.
Note 13: Random Jitter, or RJ, is measured RMS with a histogram including 1500 histogram window hits. The input voltage = VID = 500mV, 50% duty cycle at
750MHz, tr = tf = 50ps (20% to 80%).
Note 14: Deterministic Jitter, or DJ, is measured to a histogram mean with a sample size of 350 hits. Stimulus and fixture jitter has been subtracted. The input
voltage = VID = 500mV, K28.5 pattern at 1.5 Gbps, tr = tf = 50ps (20% to 80%). The K28.5 pattern is repeating bit streams of (0011111010 1100000101).
Note 15: Total Jitter, or TJ, is measured peak to peak with a histogram including 3500 window hits. Stimulus and fixture jitter has been subtracted. The input voltage
= VID = 500mV, 27-1 PRBS pattern at 1.5 Gbps, tr = tf = 50ps (20% to 80%).
Note 16: Not Production tested. Guaranteed by statistical analysis on a sample basis at the time of characterization.
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8
SCAN15MB200
Typical Performance Characteristics
Power Supply Current vs. Bit Data Rate
Total Jitter vs. Bit Data Rate
20132820
20132821
Total Jitter measured at 0V differential while running a PRBS 27-1 pattern
with one channel active, all other channels are disabled. VDD = 3.3V, TA =
+25˚C, VID = 0.5V, pre-emphasis off.
Dynamic power supply current was measured with all channels active and
toggling at the bit data rate. Data pattern has no effect on the power
consumption. VDD = 3.3V, TA = +25˚C, VID = 0.5V, VCM = 1.2V
Total Jitter vs. Temperature
20132822
Total Jitter measured at 0V differential while running a PRBS 27-1 pattern
with one channel active, all other channels are disabled. VDD = 3.3V, VID =
0.5V, VCM = 1.2V, 1.5 Gbps data rate, pre-emphasis off.
FIGURE 2. LLP Performance Characteristics
9
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SCAN15MB200
voltage will be at the normal LVPECL levels – around 2 V.
This scheme works well with LVDS receivers that have
rail-to-rail common mode voltage, VCM, range. Most National
Semiconductor LVDS receivers have wide VCM range. The
exceptions are noted in devices’ respective datasheets.
Those LVDS devices that do have a wide VCM range do not
vary in performance significantly when receiving a signal
with a common mode other than standard LVDS VCM of 1.2
V.
TRI-STATE and Powerdown Modes
The SCAN15MB200 has output enable control on each of
the six onboard LVDS output drivers. This control allows
each output individually to be placed in a low power TRISTATE mode while the device remains active, and is useful
to reduce power consumption on unused channels. In TRISTATE mode, some outputs may remain active while some
are in TRI-STATE.
When all six of the output enables (all drivers on both channels) are deasserted (LOW), then the device enters a Powerdown mode that consumes only 0.5mA (typical) of supply
current. In this mode, the entire device is essentially powered off, including all receiver inputs, output drivers and
internal bandgap reference generators. When returning to
active mode from Powerdown mode, there is a delay until
valid data is presented at the outputs because of the ramp to
power up the internal bandgap reference generators.
Any single output enable that remains active will hold the
device in active mode even if the other five outputs are in
TRI-STATE.
20132862
FIGURE 4. AC Coupled LVPECL to LVDS Interface
When in Powerdown mode, any output enable that becomes
active will wake up the device back into active mode, even if
the other five outputs are in TRI-STATE.
An AC coupled interface is preferred when transmitter and
receiver ground references differ more than 1 V. This is a
likely scenario when transmitter and receiver devices are on
separate PCBs. Figure 4 illustrates an AC coupled interface
between a LVPECL driver and LVDS receiver. R1 and R2, if
not present in the driver device (Note 17), provide DC load
for the emitter followers and may range between 140-220Ω
for most LVPECL devices for this particular configuration.
The 15MB200 includes an internal 100Ω resistor to terminate the transmission line for minimal reflections. The signal
after ac coupling capacitors will swing around a level set by
internal biasing resistors (i.e. fail-safe) which is either VDD/2
or 0 V depending on the actual failsafe implementation. If
internal biasing is not implemented, the signal common
mode voltage will slowly drift to GND level.
Input Failsafe Biasing
External pull up and pull down resistors may be used to
provide enough of an offset to enable an input failsafe under
open-circuit conditions. This configuration ties the positive
LVDS input pin to VDD thru a pull up resistor and the
negative LVDS input pin is tied to GND by a pull down
resistor. The pull up and pull down resistors should be in the
5kΩ to 15kΩ range to minimize loading and waveform distortion to the driver. Please refer to application note AN1194, “Failsafe Biasing of LVDS Interfaces” for more information.
Interfacing LVPECL to LVDS
An LVPECL driver consists of a differential pair with coupled
emitters connected to GND via a current source. This drives
a pair of emitter-followers that require a 50Ω to VCC-2.0 load.
A modern LVPECL driver will typically include the termination
scheme within the device for the emitter follower. If the driver
does not include the load, then an external scheme must be
used. The 1.3 V supply is usually not readily available on a
PCB, therefore, a load scheme without a unique power
supply requirement may be used.
20132861
FIGURE 3. DC Coupled LVPECL to LVDS Interface
Figure 3 is a separated π termination scheme for a 3.3 V
LVPECL driver. R1 and R2 provides proper DC load for the
driver emitter followers, and may be included as part of the
driver device (Note 17). The 15MB200 includes a 100Ω input
termination for the transmission line. The common mode
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10
Design-For-Test (DfT) Features
An LVDS driver consists of a current source (nominal 3.5mA)
which drives a CMOS differential pair. It needs a differential
resistive load in the range of 70 to 130Ω to generate LVDS
levels. In a system, the load should be selected to match
transmission line characteristic differential impedance so
that the line is properly terminated. The termination resistor
should be placed as close to the receiver inputs as possible.
When interfacing an LVDS driver with a non-LVDS receiver,
one only needs to bias the LVDS signal so that it is within the
common mode range of the receiver. This may be done by
using separate biasing voltage which demands another
power supply. Some receivers have required biasing voltage
available on-chip (VT, VTT or VBB).
IEEE 1149.1 SUPPORT
The SCAN15MB200 supports a fully compliant IEEE 1149.1
interface. The Test Access Port (TAP) provides access to
boundary scan cells at each LVTTL I/O on the device for
interconnect testing. Differential pins are included in the
same boundary scan chain but instead contain IEEE1149.6
cells. IEEE1149.6 is the improved IEEE standard for testing
high-speed differential signals.
Refer to the BSDL file located on National’s website for the
details of the SCAN15MB200 IEEE 1149.1 implementation.
IEEE 1149.6 SUPPORT
AC-coupled differential interconnections on very high speed
(1+ Gbps) data paths are not testable using traditional IEEE
1149.1 techniques. The IEEE 1149.1 structures and methods are intended to test static (DC-coupled), single ended
networks. IEEE 1149.6 is specifically designed for testing
high-speed differential, including AC coupled networks.
The SCAN15MB200 is intended for high-speed signalling up
to 1.5 Gbps and includes IEEE1149.6 on all differential inputs and outputs.
20132863
FAULT INSERTION
Fault Insertion is a technique used to assist in the verification
and debug of diagnostic software. During system testing
faults are "injected" to simulate hardware failure and thus
help verify the monitoring software can detect and diagnose
these faults. In the SCAN15MB200 an IEEE1149.1 "stuckat" instruction can create a stuck-at condition, either high or
low, on any pin or combination of pins. A more detailed
description of the stuck-at feature can be found in NSC
Applications note AN-1313.
FIGURE 5. DC Coupled LVDS to LVPECL Interface
Figure 5 illustrates interface between an LVDS driver and a
LVPECL with a VT pin available. R1 and R2, if not present in
the receiver (Note 17), provide proper resistive load for the
driver and termination for the transmission line, and VT sets
desired bias for the receiver.
Packaging Information
The Leadless Leadframe Package (LLP) is a leadframe
based chip scale package (CSP) that may enhance chip
speed, reduce thermal impedance, and reduce the printed
circuit board area required for mounting. The small size and
very low profile make this package ideal for high density
PCBs used in small-scale electronic applications such as
cellular phones, pagers, and handheld PDAs. The LLP package is offered in the no Pullback configuration. In the no
Pullback configuration the standard solder pads extend and
terminate at the edge of the package. This feature offers a
visible solder fillet after board mounting.
The LLP has the following advantages:
• Low thermal resistance
• Reduced electrical parasitics
20132864
FIGURE 6. AC Coupled LVDS to LVPECL Interface
Figure 6 illustrates AC coupled interface between an LVDS
driver and LVPECL receiver without a VT pin available. The
resistors R1, R2, R3, and R4, if not present in the receiver
(Note 17), provide a load for the driver, terminate the transmission line, and bias the signal for the receiver.
• Improved board space efficiency
• Reduced package height
• Reduced package mass
For more details about LLP packaging technology, refer to
applications note AN-1187, "Leadless Leadframe Package"
Note 17: The bias networks shown above for LVPECL drivers and receivers
may or may not be present within the driver device. The LVPECL driver and
receiver specification must be reviewed closely to ensure compatibility between the driver and receiver terminations and common mode operating
ranges.
11
www.national.com
SCAN15MB200
Interfacing LVDS to LVPECL
SCAN15MB200 Dual 1.5 Gbps 2:1/1:2 LVDS Mux/Buffer with Pre-Emphasis and IEEE 1149.6
Physical Dimensions
inches (millimeters) unless otherwise noted
48-Pin LLP
NS Package Number SQA48a
Ordering Code SCAN15MB200TSQ (250 piece Tape and Reel)
SCAN15MB200TSQX (2500 piece Tape and Reel)
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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