NSC DS32ELX0421

DS32EL0421, DS32ELX0421
125 – 312.5 MHz FPGA-Link Serializer with DDR LVDS
Parallel Interface
General Description
Features
The DS32EL0421/DS32ELX0421 is a 125 MHz to 312.5 MHz
(DDR) serializer for high-speed serial transmission over FR-4
printed circuit board backplanes, balanced cables, and optical
fiber. This easy-to-use chipset integrates advanced signal
and clock conditioning functions, with an FPGA friendly interface.
The DS32EL0421/DS32ELX0421 serializes up to 5 parallel
input LVDS channels to create a maximum data payload of
3.125 Gbps. If the integrated DC-balance encoding is enabled, the maximum data payload achievable is 2.5 Gbps.
The DS32EL0421/DS32ELX0421 serializers feature remote
sense capability to automatically detect and negotiate link
status with its companion DS32EL0124/DS32ELX0124 deserializers without requiring an additional feedback path.
The parallel LVDS interface reduces FPGA I/O pins, board
trace count and alleviates EMI issues, when compared to traditional single-ended wide bus interfaces.
The DS32EL0421/DS32ELX0421 is programmable through
a SMBus interface as well as through control pins.
■
■
■
■
■
■
Target Applications
■
■
■
■
■
■
Imaging: Industrial, Medical Security, Printers
Displays: LED walls, Commercial
Video Transport
Communication Systems
Test and Measurement
Industrial Bus
■
■
■
■
■
■
■
■
■
■
■
5-bit DDR LVDS parallel data interface
Programmable transmit de-emphasis
Configurable output levels (VOD)
Selectable DC-balanced encoder
Selectable data scrambler
Remote Sense for automatic detection and negotiation of
link status
On chip LC VCOs
Redundant serial output (ELX device only)
Data valid signaling to assist with synchronization of
multiple receivers
Supports AC- and DC-coupled signaling
Integrated CML and LVDS terminations
Configurable PLL loop bandwidth
Programmable output termination (50Ω or 75Ω).
Built-in test pattern generator
Loss of lock and error reporting
Configurable via SMBus
48-pin LLP package with exposed DAP
Key Specifications
■
■
■
■
■
1.25 to 3.125 Gbps serial data rate
125 to 312.5 MHz DDR parallel clock
-40° to +85°C temperature range
>8 kV ESD (HBM) protection
Low Intrinsic Jitter — 35ps at 3.125 Gbps
Typical Application
30032101
© 2009 National Semiconductor Corporation
300321
www.national.com
DS32EL0421, DS32ELX0421 125 – 312.5 MHz FPGA-Link Serializer with DDR LVDS Parallel
Interface
June 2, 2009
DS32EL0421, DS32ELX0421
Connection Diagrams
30032102
www.national.com
2
DS32EL0421, DS32ELX0421
30032103
3
www.national.com
DS32EL0421, DS32ELX0421
Pin Descriptions
Pin Name
Pin Number I/O, Type Description
Power, Ground and Analog Reference
VDD33
VDD25
1, 36
I, VDD
3.3V supply
7, 15, 18, 25, I, VDD
35
2.5V supply
VDDPLL
28
I, VDD
3.3V supply
VOD_CTRL
14
Analog
VOD control. The serializer output amplitude can be adjusted by connecting this pin to a
pull-down resistor. The value of the resistor determines the VOD. See CML LAUNCH
AMPLITUDE for more details.
LF_CP
27
Analog
Loop filter connection for PLL
LF_REF
26
Analog
Loop filter ground reference
Exposed
Pad
49
GND
Exposed Pad must be connected to GND by 9 vias
TxOUT0+
TxOUT0-
16
17
O, CML
Inverting and non-inverting high speed CML differential outputs of the serializer. These
outputs are internally terminated.
TxOUT1+
TxOUT1-
19
20
O, CML
DS32ELX0421 ONLY. Redundancy output. Inverting and non-inverting high speed CML
differential outputs of the serializer. These outputs are internally terminated
37
38
I, LVDS
Serializer input clock. TxCLKIN+/- are the inverting and non-inverting LVDS transmit
clock input pins.
39, 40,
41, 42,
43, 44,
45, 46,
47, 48
I, LVDS
Serializer input data. TxIN[4:0]+/- are the inverting and non-inverting LVDS serializer
input data pins.
CML I/O
LVDS Parallel Data Bus
TxCLKIN+
TxCLKINTxIN[4:0]+/-
LVCMOS Control Pins
DC_B
RS
5
6
I,
DC-balance and Remote Sense pins. See Device Configuration section for device
LVCMOS behavior.
DE_EMPH0
DE_EMPH1
9
10
I,
DE_EMPH0, DE_EMPH1 select the output de-emphasis level. These pins are internally
LVCMOS pull-down.
00: Off
01: Low
10: Medium
11: Maximum
TXOUT1_E
N
12
I,
DS32ELX0421 ONLY. When held high, redundant output TxOUT1+/- is enabled. This
LVCMOS pin must be tied high when using TxOUT1+/-.
RESET
30
I,
When held low, reset the device.
LVCMOS 0 = Device Reset
1 = Normal operation
LOCK
31
O,
Lock indication output. The input data on TxIN[0:4]+/- pins is ignored when LOCK pin is
LVCMOS high.
SCK
33
I/O,
SMBus
SMBus compatible clock.
SDA
32
I/O,
SMBus
SMBus compatible data line.
SMB_CS
34
I, SMBus SMBus chip select. When held high, SMBus management control is enabled.
SMBus Interface
www.national.com
4
DS32EL0421, DS32ELX0421
Pin Name
Pin Number I/O, Type Description
Other
GPIO0
3
I/O,
Software configurable I/O pin.
LVCMOS
GPIO1
4
I/O,
Software configurable I/O pin.
LVCMOS
GPIO2
11
I/O,
Software configurable I/O pin.
LVCMOS
NC
2, 8, 12, 13, Misc.
19, 20, 21,
22, 23, 24,
29
No Connect, for DS32EL0421
2, 8, 13, 21, Misc.
22, 23, 24,
29
No Connect, for DS32ELX0421
5
www.national.com
DS32EL0421, DS32ELX0421
Absolute Maximum Ratings (Note 1)
Recommended Operating
Conditions
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (3.3V VDD33)
Supply Voltage (2.5V VDD25)
LVCMOS Input Voltage
LVCMOS Output Voltage
LVDS Input Voltage (IN+, IN-)
CML Output Voltage
Junction Temperature
Storage Temperature Range
Lead Temperature Range
Soldering (4 sec.)
Min
Supply Voltage (VDD33 –
3.135
GND)
Supply Voltage (VDD25 –
2.375
GND)
Supply Noise Amplitude
from 10 Hz to 50 MHz
Ambient Temperature (TA) -40
−0.3V to +4V
−0.3V to +3V
−0.3V to (VDD + 0.3V)
−0.3V to (VDD + 0.3V)
−0.3V to +3.6V
−0.3V to +3.6V
+125°C
-65°C to +150°C
Thermal Resistance, θJA
ESD Susceptibility
HBM (Note 2)
Typ
3.3
Max
3.465
Units
V
2.5
2.625
V
100
mVP-P
+85
°C
+25
+260°C
25°C/W
>8 kV
Power Supply Specifications
Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 3, 5)
Symbol
IDD25
Parameter
2.5V supply current
1 Output Enabled
2.5V supply current
2 Outputs Enabled
IDD33
3.3V supply current
1 Output Enabled
3.3V supply current
2 Outputs Enabled
PD
Power Consumption
1 Output Enabled
Power Consumption
2 Output Enabled
www.national.com
Condition
Typ
Max
87
94
2.5 Gbps
95
105
3.125 Gbps
101
112
1.25 Gbps
126
135
2.5 Gbps
136
145
3.125 Gbps
142
152
1.25 Gbps
74
85
2.5 Gbps
74
85
3.125 Gbps
74
85
1.25 Gbps
80
92
2.5 Gbps
80
92
3.125 Gbps
80
92
1.25 Gbps
460
540
2.5 Gbps
485
560
3.125 Gbps
500
575
1.25 Gbps
580
670
2.5 Gbps
605
695
3.125 Gbps
620
710
1.25 Gbps
6
Min
Unit
mA
mA
mW
Over recommended operating supply and temperature ranges unless otherwise specified. Applies to GPIO0, GPIO1, GPIO2,
RESET, LOCK, RS, and DC_BAL. (Notes 3, 4, 5)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
VIH
High Level Input Voltage
2.0
VDD
V
VIL
Low Level Input Voltage
0
0.8
V
VOH
High Level Output Voltage
IOH = -2mA
VOL
Low Level Output Voltage
IOL = 2mA
VCL
Input Clamp Voltage
ICL = -18mA
IIN
Input Current
VIN = 0.4V, 2.5V, or VDD
IOS
Output Short Circuit Current
VOUT = 0V
(Note 6)
2.7
3.3
V
0.3
-0.79
-35
V
-1.5
V
35
μA
42
mA
SMBus Electrical Specifications
Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 3, 4, 5)
Symbol
Parameter
VSIL
Data, Clock Input Low Voltage
VSIH
Data, Clock Input High Voltage
VSDD
Nominal Bus Voltage
iSLEAKB
Input Leakage Per Bus Segment
CSI
Capacitance for SDA and SCLK
Conditions
Min
Max
Units
0.8
V
2
VSDD
V
2.375
3.6
V
(Notes 9, 10)
Typ
±200
μA
10
pF
SMBus Timing Specifications
Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 3, 5)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
100
kHz
tSMB
Bus Operating Frequency
10
tBUF
Bus Free Time between Stop and Start Condition
4.7
μs
tHD:STA
Hold time after (repeated) start condition. After this
period, the first clock is generated.
4.0
μs
tSU:STA
Repeated Start Condition Setup Time
4.7
μs
tSU:STO
Stop Condition Setup Time
4.0
μs
tHD:DAT
Data Hold Time
300
ns
tSU:DAT
Data Setup Time
250
ns
tLOW
Clock Low Time
4.7
tHIGH
Clock High Time
4.0
tF
Clock/Data Fall Time
tR
Clock/Data Rise Time
tSU:CS
SMB_CS Setup Time
tPOR
Time in which the device must be operation after
power on
μs
20% to 80%
50
μs
300
ns
1000
ns
500
ms
30
(Note 8)
7
ns
www.national.com
DS32EL0421, DS32ELX0421
LVCMOS Electrical Specifications
DS32EL0421, DS32ELX0421
LVDS Electrical Specifications
Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 3, 4, 5)
Symbol
Parameter
Conditions
VTH
Differential Input High Threshold
VTL
Differential Input Low Threshold
VLVCM
LVDS Input Common Mode Voltage
VLVOS
LVDS Input Loss of Signal
LVDS input loss of signal level.
(Note 7)
RLVIN
Input Impedance
Internal LVDS input termination
between differential pairs.
0.05V < VLVCM < VDD25 – 0.05V
Min
Typ
Max
Units
+100
mV
-100
mV
0.05
VDD25 –
0.05
20
85
V
mVP-P
100
115
Ω
Typ
Max
Units
LVDS Timing Specifications
Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 3, 5)
Symbol
Parameter
Conditions
Min
f
Input DDR Clock (TxCLKIN) Frequency Range
312.5
MHz
tCIP
TxCLKIN Period
See Figure 3
125
3.2
2T
8
ns
tCIT
TxCLKIN Transition Time
0.5
1.0
3.0
ns
tXIT
TxIN Transition Time
See Figure 2
(Note 8)
0.15
3
ns
tCIH
TxCLKIN High Time
See Figure 3
0.7T
T
1.3T
ns
tCIL
TxCLKIN Low Time
0.7T
T
1.3T
ns
tSTC
TxIN Setup to TxCLKIN
-550
tHTC
TxIN Hold to TxCLKIN
tLVDLS
LVDS Input Clock Delay Step Size
ps
900
Programmable through the SMBus,
register 30'h
Default setting = 011'b [7:5]
See
ps
100
ps
CML Electrical Specifications
Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 3, 4, 5)
Symbol
ROT
Parameter
Output Terminations
Conditions
Min
Typ
Max
Units
On chip termination from TxOUT0/1
+ and TxOUT0/1 - to VDD25
40
50
60
Ω
60
75
90
Ω
5
%
1175
1350
1450
mVP-P
Max
Units
3.125
Gbps
50Ω mode
75Ω mode
ΔROT
Mismatch in Output Termination Resistors
VOD
Output Differential Voltage Swing
Based on VOD_CTRL = 9.1 kΩ
CML Timing Specifications
Over recommended operating supply and temperature ranges unless otherwise specified. (Notes 3, 5)
Symbol
Parameter
Conditions
LR
Line Rate
Tested with alternating 1-0 pattern.
tOS
Output Overshoot
(Note 8)
tR
Differential Low to High Transition Time
(Note 8)
tF
Differential High to Low Transition Time
tRFMM
Mismatch in Rise/Fall Time
(Note 8)
tDE
De-emphasis width
Measured from zero-crossing at
rising edge to 80% of VOD from zerocrossing at falling edge. TDE is
measured at the High setting during
test.
www.national.com
8
Min
Typ
1.25
10
%
60
90
ps
60
90
ps
15
ps
1
UI
Parameter
Conditions
Min
Typ
Max
Units
tBIT
Serializer Bit Width
0.2 x
tCIP
ns
tSD
Serializer Propagation Delay – Latency
tCIP +
5.5
ns
tJIND
Serializer Output Deterministic Jitter
Serializer output intrinsic
deterministic jitter. Measure with
PRBS-7 test pattern De-emphasis
disabled.
(Note 8)
1.25 Gbps
10
ps
2.5 Gbps
24
ps
3.125 Gbps
21
ps
jitter. Bit error rate ≥10-15.
Alternating–10 pattern. De-emphasis
disabled.
(Note 8)
1.25 Gbps
1.3
psRMS
2.5 Gbps
1.15
psRMS
3.125 Gbps
1.14
psRMS
pattern. Bit error rate ≥10-15. Deemphasis disabled.
(Note 8)
1.25 Gbps
28
ps
2.5 Gbps
38
ps
3.125 Gbps
35
ps
1.25 Gbps
3.125 Gbps
100
300
kHz
kHz
0.5
dB
tJINR
tJINT
Serializer Output Random Jitter
Peak-to-peak Serializer Output Jitter
λTXBW
Jitter Transfer Function -3 dB Bandwidth
(Note 8)
δTX
Jitter Transfer Function Peaking
(Note 8)
Serializer output intrinsic random
Serializer output peak-to-peak jitter
includes deterministic jitter, random
jitter, and jitter transfer from serializer
input. Measure with PRBS-7 test
Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability
and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or other conditions beyond those indicated in
the Recommended Operating Conditions is not implied. The Recommended Operating Conditions indicate conditions at which the device is functional and the
device should not be operated beyond such conditions.
Note 2: Human Body Model, applicable std. JESD22-A114C
Note 3: The Electrical Characteristics tables list guaranteed specifications under the listed Recommended Operating Conditions except as otherwise modified
or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and are not guaranteed.
Note 4: Current into device pins is defined as positive. Current out of device pins is defined as negative. All voltages are referenced to ground except VOD and
ΔVOD.
Note 5: Typical values represent most likely parametric norms for VCC = +3.3V and TA = +25°C, and at the Recommended Operation Conditions at the time of
product characterization and are not guaranteed.
Note 6: Output short circuit current (IOS) is specified as magnitude only, minus sign indicates direction only.
Note 7: If input LVDS signal is below 20mVP-P, loss of signal (LOS) is detected. The device will flag a valid input signal if the signal level is above 100mVP-P
Note 8: Parameter is guaranteed by characterization and is not tested at production.
Note 9: Recommended value, parameter is not tested.
Note 10: Recommended maximum capacitance load per bus segment is 400 pF.
9
www.national.com
DS32EL0421, DS32ELX0421
Symbol
DS32EL0421, DS32ELX0421
Timing Diagrams
30032106
FIGURE 1. SMBus timing parameters
30032111
FIGURE 2. Serializer Input Clock Transition Time
30032110
FIGURE 3. Serializer (LVDS Interface) Setup/Hold and High/Low Times
www.national.com
10
DS32EL0421, DS32ELX0421
30032113
FIGURE 4. LVDS Input Clock Delay
30032112
FIGURE 5. Propagation Delay Timing Diagram
30032104
FIGURE 6. 5-Bit Parallel LVDS Inputs Mapped to CML Output
11
www.national.com
DS32EL0421, DS32ELX0421
Use the following equation to obtain the desired VOD by selecting the corresponding resistor value.
Functional Description
POWER SUPPLIES
The DS32EL0421 and DS32ELX0421 have several power
supply pins, at 2.5V as well as 3.3V. It is important that these
pins all be connected and properly bypassed. Bypassing
should consist of parallel 4.7μF and 0.1μF capacitors as a
minimum, with a 0.1μF capacitor on each power pin. A 22 μF
capacitor is required on the VDDPLL pin which is connected
to the 3.3V rail.
These devices have a large contact in the center on the bottom of the package. This contact must be connected to the
system GND as it is the major ground connection for the device.
R = (1400 mV / VOD) x 9.1 kΩ
The CML output launch amplitude can also be adjusted by
writing to SMBus register 69'h, bits 2:0. This register is meant
to assist system designers during the initial prototype design
phase. For final production, it is recommended that the appropriate resistor value be selected for the desired VOD and
that register 69'h be left to its default value.
REMOTE SENSE
The remote sense feature can be used when a DS32EL0421
or DS32ELX0421 serializer is directly connected to a
DS32EL0124 or DS32ELX0124 deserializer. Active components in the signal path between the serializer and the deserializer may interfere with the back channel signaling of the
devices.
When remote sense is enabled, the serializer will cycle
through four states to successfully establish a link and align
the data. The state diagram for the serializer is shown in Figure 7. The serializer will remain in the low power IDLE state
until it receives an input clock. Once the PLL of the serializer
has locked to the input clock, the device will enter the LINK
DETECT state. While in this state, the serializer will monitor
the line to see if the deserializer is present. If a deserializer is
detected, the serializer will enter the LINK ACQUISITION
state. The serializer will transmit the entire training pattern
and then enter the NORMAL state. If the deserializer is unable
to successfully lock or maintain lock it will break the link,
sending the serializer back to the IDLE or LINK DETECT
states.
With the Remote Sense feature active, the serializer can be
forced out of lock due to events on the high speed serial line
in two ways, a serial channel reset signal is sent upstream
from the deserializer or the near end termination detect circuit
signals and open termination was detected. The upstream
signal sent from the deserializer that resets the serializer is
called the link detect signal. Since the serializer and deserializer may power up at different times, the deserializer will
transmit this link detect signal periodically, once it detects that
a serializer is active on the other side of the high speed line.
When a serializer receives the link detect signal, it will return
to the LINK DETECT state. The near end open termination
detection circuit will trigger only for near end open termination
events, such as unplugging the cable on the serializer end of
the line.
POWER UP
It is recommended, although not necessary, to bring up the
3.3V power supply before the 2.5V supply. If the 2.5V supply
is powered up first, an initial current draw of approximately
600mA from the 2.5V rail may occur before settling to its final
value. Regardless of the sequence, both power rails should
monotonically ramp up to their final values.
POWER MANAGEMENT
These devices have two methods to reduce power consumption. To enter the first power save mode, the on board host
FPGA or controlling device can cease to output the DDR
transmit clock. To further reduce power consumption, write
40'h to register 26'h and 10'h to register 01'h. This will put the
device in its lowest power consumption mode.
RESET
There are three ways to reset these devices. A reset occurs
automatically during power-up. The device can also be reset
by pulling the RESET pin low, with normal operation resuming
when the pin is driven high again. The device can also be
reset by writing to the reset register. This reset will put all of
the register values back to their default values, except it will
not affect the address register value if the SMBus default address has been changed.
LVDS INPUTS
The DS32EL0421 and DS32ELX0421 have standard 2.5V
LVDS inputs which are compliant with ANSI/TIA/EIA-644.
These inputs have internal 100Ω termination resistors. It is
recommended that the PCB trace between the FPGA and the
serializer be less than 40-inches. Longer PCB traces may
degrade the quality of the input signal. The connection between the host and the DS32EL0421 or DS32ELX0421
should be over a controlled impedance transmission line with
impedance that matches the termination resistor – usually
100Ω. Setup and hold times are specified in the LVDS Switching Characteristics table, however the clock delay can be
adjusted by writing to register 30’h.
DC-BALANCE ENCODER
The DS32EL0421 and DS32ELX0421 have a built-in DC-balance encoder to support AC-coupled applications. When enabled, the input signal on TXIN4+/- is treated as a data valid
bit. If TXIN4+/- is low, then the four bit nibbles from TXIN0TXIN3 are taken to form a 16 bit word. This 16 bit word is
processed as two 8 bit words and converted to two 10 bit
words by using the standard 8b/10b data coding scheme. The
two 10 bit words are then combined to create a 20 bit code.
This 20 bit word is serialized and driven on the output. The
nibble taken in on the rising edge of the clock is the most significant nibble and the nibble taken in on the falling edge is
the least significant nibble. If TXIN4+/TXIN4- is high, then the
inputs TXIN0 -TXIN3 are ignored and a programmable DCbalanced SYNC character is inserted in the output stream.
The default character is a K28.5 code. In order to send other
K codes, they must first be programmed into the serializer via
the SMBus. The SMBus registers allows for only a single programmable character.
LOOP FILTER
The DS32EL0421 and DS32ELX0421 have an internal PLL
which is used to generate the serialization clock from the parallel clock input. The loop filter for this PLL is external; and for
optimum results, a 100nF capacitor and a 1.5 kΩ resistor in
series should be connected between pins 26 and 27. See
typical interface circuit (Figure 12).
CML LAUNCH AMPLITUDE
The launch amplitude of the CML output(s) is controlled by
placing a single resistor from the VOD_CTRL pin to ground.
www.national.com
12
DS32EL0421, DS32ELX0421
30032115
FIGURE 7. Serializer State Diagram
phasis is user programmable through either device pins
DE_EMPH0 and DE_EMPH1 or SMBus interface. Users can
control the strength of the de-emphasis to optimize for a specific system environment. Please see the De-Emphasis Control Table for details.
SCRAMBLER and NRZI Encoder
The CDR of the DS32EL0124 and the DS32ELX0124 expect
a transition density of 20% for a period of 200 μs. If the scrambler and NRZI encoder are enabled, the raw or DC-balanced
serialized data is scrambled to improve transition density. The
scrambler accepts 20 bits of data and encodes it using the
polynomial X9 + X4 + 1. The data can then be sent to the NRZto-NRZI converter before being output.
Enabling the scrambler can help to lower EMI emissions by
spreading the spectrum of the data. Scrambling also creates
transitions for the deserializer’s CDR to properly lock onto.
The scrambler and NRZI encoder are enabled or disabled by
default depending on how the DC_B and RS pins are configured. To override the default scrambler setting two register
writes must be performed. First, write to register 22’h and set
bit 3 to unlock the scrambler register. Next write to register
21’h and change bit 4 to the desired value. The NRZI encoder
can be enabled or disabled independently of the scrambler by
controlling bit 7 of register 21'h and bit 4 of register 22'h.
De-Emphasis Control Table
DE_EMPH[1:0]
Output De-Emphasis Level
00'b
Off
01'b
Low
10'b
Medium
11'b
High
The DS32ELX0421 provides a secondary serial output, supporting redundancy applications. The redundant output driver
can be enabled by setting TXOUT1_EN pin to HIGH or by
activating it through the SMBus reigsters.
DEVICE CONFIGURATION
There are four ways to configure the DS32EL0421 and
DS32ELX0421 serializers, these combinations are shown in
Table 1. Refer to Figure 7 to see how the combinations of the
RS and DC_B pins change the link startup behavior of the
serializers. When connecting to a deserializer other than the
DS32EL0124 or DS32ELX0124, Remote Sense should be
disabled. The scrambler and NRZI encoder shown in Table
1 can be enabled or disabled through register programming.
When Remote Sense is enabled, with RS pin tied low, the
serializer must be connected directly to a DS32EL0124 or
DS32ELX0124 deserializer without any active components
between them. The Remote Sense module features an upstream communication method for the serializer and deseri-
CML OUTPUT DATA INTERFACING
The serial outputs provide low-skew differential signals. Internal resistors connected from TxOUTn+ and TxOUTn- to
VDD25 terminate the outputs. The output level can be programmed by adjusting the pull-down resistor to the
VOD_CTRL pin. The output terminations can also be programmed to be either 50 Ω or 75 Ω.
The output buffer consists of a current mode logic (CML) driver with user configurable de-emphasis control, which can be
used to optimize performance over a wide range of transmission line lengths and attenuation distortions resulting from low
cost CAT(-5, -6, -7) cable or FR–4 backplane. Output de-em-
13
www.national.com
DS32EL0421, DS32ELX0421
alizer to communicate. This feature is used to pass link status
information between the 2 devices. When Remote Sense is
enabled the serializer will send a training pattern to the deserializer to establish lock and lane alignment.
If DC-Balance is enabled, a maximum of 4 parallel LVDS
lanes can be used to receive data. The fifth lane (TXIN4±) is
used for Data Valid signaling. Each time a serializer establishes a link to a deserializer with DC-Balance enabled and
Remote Sense disabled, the Data Valid input to the serializer
must be held high for 110 LVDS clock periods. If the Data
Valid input to the serializer is logic HIGH, then SYNC characters are transmitted. If the deserializer receives a SYNC
character, then the LVDS data outputs will all be logic low and
the Data Valid output will be logic high. If the deserializer detects a DC-Balance code error, the output data pins will be
set to logic high with the Data Valid output also set to logic
high.
In the case where DC-Balance is enabled and Remote Sense
is disabled, with RS set to high and DC_B set to low, it is
recommended that the host device periodically toggle the Da-
ta Valid input to the serializer, to transmit SYNC symbols on
the line, to ensure that the deserializer is and remains locked.
In this configuration the deserializer or receiving device does
not have a way to directly notify the serializer if it has lost lock.
Periodically sending SYNC symbols will allow the receiving
system to reacquire lock if a problem has occurred. With these
pin settings the DS32EL0421/DS32ELX0421 and
DS32EL0124/DS32ELX0124 devices can interface with other
active component in the high speed signal path, such as fiber
modules.
When both Remote Sense and DC-Balance are disabled,
RS and DC_B pins set to high, the LVDS lane alignment is
not maintained. In this configuration, data formatting is handled by an FPGA or external source. This pin setting combination also allows for the DS32EL0421/DS32ELX0421 devices to interface with active components other than the
DS32EL0124/DS32ELX0124 in the high speed signal path.
In this configuration the host device is responsible for DC balancing the data in an AC coupled application.
TABLE 1. Device Configuration Table
Remote Sense Pin (RS)
DC-Balance Pin (DC_B)
Configuration
0
0
Remote Sense enabled
DC-Balance enabled
Data Alignment
Scrambler and NRZI encoder disabled by default
0
1
Remote Sense enabled
DC-Balance disabled
Data Alignment
Scrambler and NRZI encoder enabled by default
1
0
Remote Sense disabled
DC-Balance enabled
Data Alignment
Scrambler and NRZI encoder enabled by default
1
1
Remote Sense disabled
DC-Balance disabled
No Data Alignment
Scrambler and NRZI encoder disabled by default
www.national.com
14
The Host de-selects the device by driving its SMBus CS
signal Low.
The WRITE transaction is completed, the bus goes IDLE and
communication with other SMBus devices may now occur.
Reading a Register
To read a register, the following protocol is used (see SMBus
2.0 specification).
1. The Host (Master) selects the device by driving its
SMBus Chip Select (SMB_CS) signal HIGH.
2. The Host drives a START condition, the 7-bit SMBus
address, and a “0” indicating a WRITE.
3. The Device (Slave) drives the ACK bit (“0”).
4. The Host drives the 8-bit Register Address.
5. The Device drives an ACK bit (“0”).
6. The Host drives a START condition.
7. The Host drives the 7-bit SMBus Address, and a “1”
indicating a READ.
8. The Device drives an ACK bit “0”.
9. The Device drives the 8-bit data value (register contents).
10. The Host drives a NACK bit “1”indicating end of the
READ transfer.
11. The Host drives a STOP condition.
12. The Host de-selects the device by driving its SMBus CS
signal Low.
The READ transaction is completed, the bus goes IDLE and
communication with other SMBus devices may now occur.
Transfer of Data via the SMBus
During normal operation the data on SDA must be stable during the time when SCK is HIGH.
There are three unique states for the SMBus:
START A HIGH to LOW transition on SDA while SCK is
HIGH indicates a message START condition
STOP A LOW to HIGH transition on SDA while SCK is
HIGH indicates a message STOP condition.
IDLE
If SCK and SDA are both high for a time exceeding
tBUF from the last detected STOP condition or if they
are HIGH for a total exceeding the maximum
specification for tHIGH then the bus will transfer to
the IDLE state.
SMBus Configurations
Many different configurations of the SMBus are possible and
depend upon the specific requirements of the applications.
Several possible applications are described.
Configuration 1
The deserializer SMB_CS may be tied High (always enabled)
since it is the only device on the SMBus. See Figure 8.
SMBus Transactions
The devices support WRITE and READ transactions. See
Register Description Table for register address, type (Read/
Write, Read Only), default value and function information.
Configuration 2
Since the multiple SER devices have the same address, the
use of the individual SMB_CS signals is required. To communicate with a specific device, its SMB_CS is driven High to
select the device. After the transaction is complete, its
SMB_CS is driven Low to disable its SMB interface. Other
devices on the bus may now be selected with their respective
chip select signals and communicated with. See Figure 9.
Writing to a Register
To write a register, the following protocol is used (see SMBus
2.0 specification).
1. The Host (Master) selects the device by driving its
SMBus Chip Select (SMB_CS) signal HIGH.
2. The Host drives a START condition, the 7-bit SMBus
address, and a “0” indicating a WRITE.
3. The Device (Slave) drives the ACK bit (“0”).
4. The Host drives the 8-bit Register Address.
5. The Device drives an ACK bit (“0”).
6. The Host drive the 8-bit data byte.
7. The Device drives an ACK bit (“0”).
8. The Host drives a STOP condition.
Configuration 3
The addressing field is limited to 7-bits by the SMBus protocol.
Thus it is possible that multiple devices may share the same
7-bit address. An optional feature in the SMBus 2.0 specification supports an Address Resolution Protocol (ARP). This
optional feature is not supported by the DS32EL0421/
DS32ELX0421 devices. Solutions for this include: the use of
the independent SMB_CS signals, independent SMBus segments, or other means.
15
www.national.com
DS32EL0421, DS32ELX0421
9.
SMBus INTERFACE
The System Management Bus interface is compatible to SMBus 2.0 physical layer specification. The use of the Chip
Select signal is required. Holding the SMB_CS pin HIGH enables the SMBus port, allowing access to the configuration
registers. Holding the SMB_CS pin LOW disables the
device's SMBus, allowing communication from the host to
other slave devices on the bus. In the STANDBY state, the
System Management Bus remains active. When communication to other devices on the SMBus is active, the SMB_CS
signal for the serializer must be driven LOW.
The address byte for all DS32EL0421 and DS32ELX0421
devices is AE'h. Based on the SMBus 2.0 specification, these
devices have a 7-bit slave address of 1010111'b. The LSB is
set to 0'b (for a WRITE), thus the 8-bit value is 1010 1110 'b
or AE'h.
The SCK and SDA pins are 3.3V LVCMOS signaling and include high-Z internal pull up resistors. External low
impedance pull up resistors maybe required depending upon
SMBus loading and speed. Note, these pins are not 5V tolerant.
DS32EL0421, DS32ELX0421
30032107
FIGURE 8. SMBus Configuration 1
30032108
FIGURE 9. SMBus Configuration 2
30032109
FIGURE 10. SMBus Daisy Chained CS Configuration
www.national.com
16
30032116
FIGURE 11. Serializer Propagation Delay
17
www.national.com
DS32EL0421, DS32ELX0421
Each clock cycle shown in Figure 11 is defined to be 1/20th
of the high speed serial bit rate. For example, at a serial line
rate of 3.125 Gbps the clock frequency of each delay cycle
would be 156.25 MHz. Note, this is not the same frequency
as the LVDS inputs, which would be 312.5 MHz (625 Mbps)
for a serial line rate of 3.125 Gbps. Dashed lines in Figure
11 indicate that the feature is disabled by default in that mode
and therefore add no more time to the total propagation delay.
PROPAGATION DELAY
Once the serializer is locked, the amount of time it takes for
a bit to travel into the device through the DDR LVDS inputs
and out through the CML serial output is defined to be the
propagation delay. The propagation delay through the
DS32EL0421/DS32ELX0421 due to the analog circuitry is
considered negligible compared to the time delay caused by
the digital components. The information presented in this section allows system designers to predict the propagation delay
through the device in terms of clock cycles which are proportional to the high speed serial line rate.
DS32EL0421, DS32ELX0421
activated “on-the-go”, if a problem is detected on the primary
link. See the Redundancy / Fail Over Configuration section
located under Register Recipes.
Applications Information
GPIO PINS
The GPIO pins can be useful tools when debugging or evaluating the system. For specific GPIO configurations and functions refer to registers 2, 3, 4, 5 and 6 in the device register
map.
GPIO pins are commonly used when there are multiple serializers on the same SMBus. In order to program individual
settings into each serializer, they will each need to have a
unique SMBus address. To reprogram multiple serializers on
a single SMBus, configure the first serializer such that the
SMBus lines are connected to the FPGA or host controller.
The CS pin of the second serializer should be tied to GPIO0
of the first serializer, with the CS pin of the next serializer tied
to GPIO0 of its preceding serializer. By holding all of the
GPIO0 pins low, the first serializer’s address may now be reprogrammed by writing to register 0. The first serializer’s
GPIO pin can now be asserted and the second serializer’s
address may now be reprogrammed.
LINK AGGREGATION
Multiple DS32EL0421/DS32ELX0421 serializers and
D32EL0124/DS32ELX0124 deserializers can be aggregated
together if an application requires a data throughput of more
than 3.125 Gbps. By utilizing the data valid signal of each
device, the system can be properly deskewed to allow for a
single cable, such as CAT-6, DVI-D, or HDMI, to carry data
payloads beyond 3.125 Gbps. The ELXLEVK01 evaluation kit
includes sample IP for a link aggregation system to operate
at an application throughput of up to 6.25 Gbps.
Link aggregation configurations can also be implemented in
applications which require longer cable lengths. In these type
of applications the data rate of each serializer and deserializer
chipset can be reduced, such that the applications' net data
throughput is still the same. Since each high speed channel
is now operating at a fraction of the original data rate, the loss
over the cable is reduced, allowing for greater lengths of cable
to be used in the system.
HIGH SPEED COMMUNICATION MEDIA
Using the serializer’s integrated de-emphasis blocks in combination with the DS32EL0124 or DS32ELX0124’s integrated
equalization blocks allows data to be transmitted across a
variety of media at high speeds. Factors that can limit device
performance include excessive input clock jitter, noisy power
rails, EMI from nearby noisy components and poor layout
techniques. Although many cables contain wires of similar
gauge and shielding, performance can vary greatly depending on the quality of the connector.
LAYOUT GUIDELINES
It is important to follow good layout practices for high speed
devices. The length of LVDS input traces should not exceed
40 inches. In noisy environment the LVDS traces may need
to be shorter to prevent data corruption due to EMI. Noisy
components should not be placed next to the LVDS or CML
traces. The LVDS and CML traces must have a controlled
differential impedance of 100 Ω. Do not place termination resistor at the LVDS inputs or CML outputs, the DS32EL0421
and DS32ELX0421 have internal termination resistors. It is
recommended to avoid using vias. Vias create an impedance
mismatch in the transmission line and result in reflections,
which can greatly lower the maximum distance of the high
speed data link. If vias are required, they should be placed
symmetrically on each side of the differential pair. For more
tips and detailed suggestions regarding high speed board
layout principles, please consult the LVDS Owner’s Manual.
REDUNDANCY APPLICATIONS
The DS32ELX0421 has two high speed CML serial outputs.
SMBus register control allows the device to use a single output exclusively, or both outputs simultaneously. This allows a
single serializer to transmit data to two independant receiving
systems, a primary and secondary endpoint. Some applications require a redundancy measure in case the primary
signal path is compromised. The secondary output can be
www.national.com
18
DS32EL0421, DS32ELX0421
30032105
FIGURE 12. Typical Interface Circuit
19
www.national.com
DS32EL0421, DS32ELX0421
Typical Performance Characteristics
The eye diagrams shown below illustrate the typical performace of the DS32ELX0421/DS32EL0421 configured with
RS = 0,DC_B = 0, for the conditions listed below each figure.
The PRBS-15 data was generated by a low cost FPGA, which
used an LMK03000C to generate the various clock frequencies.
30032117
30032118
CML Serial Differential Output 1.25 Gbps
CML Serial Differential Output 3.125 Gbps
30032119
30032120
CML Serial Singled Ended Output (+) 1.25 Gbps
www.national.com
CML Serial Single Ended Output (+) 3.125 Gbps
20
The register information for the serializer is shown in the table
below. Some registers have been omitted or marked as reAddr
(Hex)
Name
00
Device ID
01
Reset
02
03
04
GPIO0 Config
GPIO1 Config
GPIO2 Config
Bits
Field
R/W
Default
Description
7:1
SMBus Address
R/W
57'h
Some systems will use all 8 bits as the device ID. This
will shift the value from 57’h to AE’h
0
Reserved
0
7:5
Reserved
0
4
Analog Disable
3:1
Reserved
0
Software Reset
7:4
GPIO0 Mode
3:2
GPIO0 R Enable R/W
1
Input Enable
R/W
0
0
Output Enable
R/W
1'b
7:4
GPIO1 Mode
R/W
0
0000: Power on reset
0001: GP out register
0010: PLL lock indicator
0011: TxIN0 loss of signal
0100: TxIN1 loss of signal
0101: TxIN2 loss of signal
0110: TxIN3 loss of signal
0111: TxIN4 loss of signal
All others: Reserverd
3:2
GPIO1 R Enable R/W
01'b
00: Pullup/down disabled
01: Pulldown enabled
10: Pullup enabled
11: Reserved
1
Input Enable
R/W
0
0
Output Enable
R/W
1'b
7:4
GPIO2 Mode
R/W
0
3:2
GPIO2 R Enable R/W
1
Input Enable
R/W
0
0
Output Enable
R/W
1'b
R/W
0
1: Disables analog blocks. Power save feature
0
R/W
0
1: Reset the device. Does not affect device ID.
0
0000: GP out register
0001: Link loss indicator
0011: TxCLKIN loss of signal
0100: TxCLKIN detect
All others: Reserved
01'b
01'b
21
00: Pullup/down disabled
01: Pulldown enabled
10: Pullup enabled
11: Reserved
0: Input buffer disabled
1: Input buffer enabled
0: OutputTtri-State™
1: Output enabled
0: Input buffer disabled
1: Input buffer enabled
0: Output Tri-State™
1: Output enabled
0000: GP out register
0001: Always on clock out
0010: Parallel-to-serial clock out
0100: Digital clock out
All others: Reserverd
00: Pullup/down disabled
01: Pulldown enabled
10: Pullup enabled
11: Reserved
0: Input buffer disabled
1: Input buffer enabled
0: Output Tri-State™
1: Output enabled
www.national.com
DS32EL0421, DS32ELX0421
served; these are for internal testing and should not be written
to. Some register bits require an override bit to be set before
they can be written to.
Register Map
DS32EL0421, DS32ELX0421
Addr
(Hex)
Name
05
GP In
06
GP Out
Bits
Field
R/W
Default
Description
7:3
Reserved
2
GP In 2
R
0
0
Input value on GPIO2
1
GP In 1
R
0
Input value on GPIO1
0
GP In 0
R
0
Input value on GPIO0
7:3
Reserved
2
GP Out 2
R/W
0
Output value on GPIO2
1
GP Out 1
R/W
0
Output value on GPIO1
0
GP Out 0
R/W
0
Output value on GPIO0
7:3
Reserved
2
Pin Override
R/W
0
0: Pin values determine setting
1: Register overrides pin values
1:0
De-emphasis
level
R/W
0
00: No de-emphasis
01: Low
10: Medium
11: High
7
NRZI enable
R/W
0
1: Enable NRZI, if override bit is set
6
DV disable
R/W
0
1: Disable Data Valid
5
Reserved
R/W
0
4
Scrambler
Enable
R/W
0
1: Scrambler enable, requires override bit to change
setting
3
DC Bal encoder
bypass
R/W
0
1: Bypass encoder, requires override bit to change
setting
2
Training
Sequence
Enable
R/W
0
1: Enable training sequence, requires override bit to
change setting
1:0
Device
Configuration
R/W
0
MSB: Remote Sense enable, active low
LSB: DC balance encoder enable, active low
Requires override bit to change settings through
registers. Normally controlled by pins. See Table 1 for
more information.
7:5
Reserved
4
NRZ bypass
override
R/W
0
1: Unlock reg 21’h bit 7
3
Scrambler
bypass override
R/W
0
1: Unlock reg 21’h bit 4
2
DC Bal encoder
bypass override
R/W
0
1: Unlock reg 21’h bit 3
1
Training
sequence
enable override
R/W
0
1: Unlock reg 21’h bit 2
0
Config pin
override
R/W
0
1: Unlock reg 21’h bits 1 and 0
7
TxCLKIN Delay
Bypass
R/W
0
0: TxCLKIN delay enable
1: Bypass TxCLKIN delay
6:0
Reserved
0
07–1F Reserved
20
21
22
De-Emphasis
Device Config
Device Config
Override
0
0
23 Reserved
24
LVDS Clock
Delay Enable
0
25 Reserved
www.national.com
22
26
27
28
29
2A
Name
Power Down
Event Disable
Bits
Event Status
R/W
Default
Description
7
Channel Reset
R/W
0
1: Reset high speed channel. Self-clearing bit.
6
Clock
Powerdown
R/W
0
1: Power down parallel, parallel-to-serial, and always
on clock
5
LVDS Clock
enable
R/W
1'b
0: Disable TxCLKIN
1: Enable TxCLKIN
4
TxIN4 Enable
R/W
1'b
0: Disable TxIN4
1: Enable TxIN4
3
TxIN3 Enable
R/W
1'b
0: Disable TxIN3
1: Enable TxIN3
2
TxIN2 Enable
R/W
1'b
0: Disable TxIN2
1: Enable TxIN2
1
TxIN1 Enable
R/W
1'b
0: Disable TxIN1
1: Enable TxIN1
0
TxIN0 Enable
R/W
1'b
0: Disable TxIN0
1: Enable TxIN0
7:5
Reserved
R/W
0
4
PLL Lock
Disable
R/W
0
0: Count clock errors
1: Clock error count disabled
3
FIFO Error
Disable
R/W
0
0: Count FIFO erros 1: FIFO error count disabled
2
Parallel Clock
Detect Disable
R/W
0
0: Count clock detect errors
1: Clock detect count disabled
1
Clock Loss of
Signal Disable
R/W
0
0: Count clock los of signal errors
1: Clock loss of signal count disabled
0
Data Loss of
Signal Disable
R/W
0
0: Count data los of signal errors
1: Clock data of signal count disabled
LVDS Operation 7:2
Loss of Signal
Status
Field
Reserved
0
1
LVDS Loss of
Signal Preset
R/W
0
1: Preset signal for LVDS loss of signal register
0
LVDS Loss of
Signal Reset
R/W
0
1: Clear signal for LVDS loss of signal register
7:6
Reserved
5
Clock Loss of
Signal
R
0
0: Clock present
1: No clock present on TxCLKIN
4:0
Data Loss of
Signal
R
0
0: Data present
1: No data present on TxIN4:0
7:4
Reserved
3
TxCLKIN Detect
2
Reserved
1:0
Link Detect 1:0
0
0
R/W
0
0: TxCLKIN not detected
1: TxCLKIN detected
0
R/W
0
23
0: Link not detected
1: Link detected
www.national.com
DS32EL0421, DS32ELX0421
Addr
(Hex)
DS32EL0421, DS32ELX0421
Addr
(Hex)
2B
2C
Name
Event Config
Event Count
Bits
Field
R/W
Default
Description
7
Reserved
6
PLL Lock Event
R/W
0
0
0: Count PLL lock events
1: Do not count PLL lock events
5
Link Event
R/W
0
0: Count link events
1: Do not count link events
4
Loss of Signal
Event
R/W
0
0: Count loss of signal events
1: Do not count loss of signal events
3
Event Count
Select
R/W
0
0: Select PLL event count for reading
1: Select link event count for reading
2
Clear PLL Error
Count
R/W
0
1: Reset PLL error count. Self clearing bit.
1
Clear Link Error
Count
R/W
0
1: Reset link error count. Self clearing bit.
0
Enable Count
R/W
0
0: Disable event counters
1: Enable event counters
7:0
Event Counter
R
0
7
Reserved
6
Reverse Data
Order
R/W
0
5:2
Reserved
R/W
0
1
Link Detect 1
R/W
0
Link detect value for channel 1
0
Link Detect 0
R/W
0
Link detect value for channel 0
7:6
Reserved
5
Output
Termination
R/W
1'b
0: 75 Ω terminations
1: 50 Ω terminations
4
Link Start
R/W
1'b
0: Start when TxOUT0 or TxOUT1 link
1: Start when TxOUT0 and TxOUT1 linke
3
Link Stop
R/W
1'b
0: Stop when TxOUT0 and TxOUT1 both links invalid
1: Stop when TxOUT0 or TxOUT1 break link, either
link is invalid
2
TxOUT Override
R/W
0
0: TxOUT0 enabled by default, TxOUT1_en pin
controls channel1
1: Override enable of TxOUT0 and TxOUT1
1
TxOUT1 Enable
R/W
0
0: TxOUT1 disabled
1: TxOUT1 enabled
For proper operation of TxOUT1, the TxOUT1_EN pin
must be held high.
0
TxOOUT0
Enable
R/W
0
0: TxOUT0 disabled
1: TxOUT0 enabled
7:5
TxCLKIN Delay
R/W
011’b
4:0
Reserved
2D Reserved
2E
2F
30
Analog Driver
Tx Config
Clock Delay
0
0
00010’b
31–68 Reserved
www.national.com
0: Normal
1: Reverse output data order
24
000: Min clock delay, 350 ps
011: 725 ps
111: Max clock delay, 1225 ps
69
Name
Bits
Output Amplitude 7:3
Adjust
2:0
Field
R/W
Default
Reserved
Amplitude Adjust R/W
DS32EL0421, DS32ELX0421
Addr
(Hex)
Description
0
011’b
25
000: Level 7
001: Level 8 (Highest output)
010: Level 5
011: Level 6 (Normal output)
100: Level 4
101: Level 3
110: Level 2
111: Level 1 (Lowest output)
www.national.com
DS32EL0421, DS32ELX0421
this is done with a high speed real time oscilloscope or a
sampling oscilloscope. Sampling oscilloscopes require a reference clock to trigger on. The following recipe can be used
to bring out the serial clock on GPIO2 to provide a trigger for
sampling oscilloscopes.
Reg 04’h, write 21’h
Register Recipes
Many features of the serializer contained within the SMBus
registers require multiple writes to configure and enable. This
methodology was implemented to prevent accidental register
writes from causing undesired device behavior. Several
recipes for common features are listed below. When experimenting with other SMBus register features, be sure to read
through the register map for override and enable bits.
Power Save Mode
When a system does not need to transmit high speed data
from the DS32EL0421 or DS32ELX0421, the power consumption of the device can be managed as described in the
Power Management section on the Functional Description
page. The following recipe powers down many of the analog
and digital blocks in the serializer, but leaves the SMBus
module operational. Please note that in order to resume normal operation the recipe below will have to be unwritten.
Reg 01'h, write 10'h
Reg 26'h, write 40'h
SCRAMBLER OVERRIDE CONTROL
The scrambler’s default settings are described in the device
configuration section. However, the scrambler’s setting can
be overridden if desired.
Reg 22’h, write 08’h
Reg 21’h, write to bit 3 to enable/disable
75Ω MODE
The serializer can be programmed to interface with 75Ω media by using the recipe shown below. The inverting serial
output should be terminated when interfacing with single ended media.
Reg 2F’h, write 0 to bit 5
Redundancy / Fail Over Configuration
DS32ELX0421 only. Implementing a redundancy system
with the DS32ELX0421 can be done in several ways. One
method would be to program the redundancy or fail over logic
into the host device or FPGA. The recipe below will describe
a different method, for which a DS32ELX0421 will communicate to two different DS32EL0124 deserializers. The recipe
below will configure the DS32ELX0421 serializer to automatically switch to the alternate output when the current high
speed link fails.
Configure all device with Remote Sense enabled either by pin
or register control.
Pull TxOUT1_EN pin high
reg 2F'h, write 2D'h
Reg 2F'h, write 28'h
OUTPUT CHANNEL MUX CONTROL
DS32ELX0421 only. TxOUT0 is the output channel enabled
by default. By using the external pin TxOUT1_EN, TxOUT1
will be activated along with TxOUT0. If an application requires
that only one channel be active at a time, the following recipe
allows for each channel to be enabled or disabled independent of the other.
Reg 2F’h, write 1’b to bit 2
Reg 2F’h, write to bits 1 or 0 to control the output channels
OUTPUT THE SERIAL CLOCK ON GPIO2
It is very helpful to be able to monitor high speed communication systems and observe their signal integrity. Generally,
www.national.com
26
DS32EL0421, DS32ELX0421
Physical Dimensions inches (millimeters) unless otherwise noted
48–Lead LLP Plastic Quad Package
NS Package Number SQA48A
(See AN-1187 for PCB Design and Assembly Recommendations)
27
www.national.com
DS32EL0421, DS32ELX0421 125 – 312.5 MHz FPGA-Link Serializer with DDR LVDS Parallel
Interface
Notes
For more National Semiconductor product information and proven design tools, visit the following Web sites at:
Products
Design Support
Amplifiers
www.national.com/amplifiers
WEBENCH® Tools
www.national.com/webench
Audio
www.national.com/audio
App Notes
www.national.com/appnotes
Clock and Timing
www.national.com/timing
Reference Designs
www.national.com/refdesigns
Data Converters
www.national.com/adc
Samples
www.national.com/samples
Interface
www.national.com/interface
Eval Boards
www.national.com/evalboards
LVDS
www.national.com/lvds
Packaging
www.national.com/packaging
Power Management
www.national.com/power
Green Compliance
www.national.com/quality/green
Switching Regulators
www.national.com/switchers
Distributors
www.national.com/contacts
LDOs
www.national.com/ldo
Quality and Reliability
www.national.com/quality
LED Lighting
www.national.com/led
Feedback/Support
www.national.com/feedback
Voltage Reference
www.national.com/vref
Design Made Easy
www.national.com/easy
www.national.com/powerwise
Solutions
www.national.com/solutions
Mil/Aero
www.national.com/milaero
PowerWise® Solutions
Serial Digital Interface (SDI) www.national.com/sdi
Temperature Sensors
www.national.com/tempsensors SolarMagic™
www.national.com/solarmagic
Wireless (PLL/VCO)
www.national.com/wireless
www.national.com/training
PowerWise® Design
University
THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION
(“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY
OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO
SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS,
IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS
DOCUMENT.
TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT
NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL
PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR
APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND
APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE
NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS.
EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO
LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE
AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR
PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY
RIGHT.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR
SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and
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. A critical component is any component in 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 safety or effectiveness.
National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other
brand or product names may be trademarks or registered trademarks of their respective holders.
Copyright© 2009 National Semiconductor Corporation
For the most current product information visit us at www.national.com
National Semiconductor
Americas Technical
Support Center
Email: [email protected]
Tel: 1-800-272-9959
www.national.com
National Semiconductor Europe
Technical Support Center
Email: [email protected]
National Semiconductor Asia
Pacific Technical Support Center
Email: [email protected]
National Semiconductor Japan
Technical Support Center
Email: [email protected]