DS92LV1021AMSAX [TI]
16-40 MHz 10 Bit Bus LVDS Serializer;
| 型号： | DS92LV1021AMSAX |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 16-40 MHz 10 Bit Bus LVDS Serializer 驱动 光电二极管 接口集成电路 驱动器 |
| 文件： | 总17页 (文件大小：375K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DS92LV1212A
DS92LV1212A 16-40 MHz 10-Bit Bus LVDS Random Lock Deserializer with
Embedded Clock Recovery
Literature Number: SNLS071D
November 2000
DS92LV1212A
16-40 MHz 10-Bit Bus LVDS Random Lock Deserializer
with Embedded Clock Recovery
General Description
Features
n Clock recovery without SYNC patterns-random lock
n Guaranteed transition every data transfer cycle
The DS92LV1212A is an upgrade of the DS92LV1212. It
maintains all of the features of the DS92LV1212. The
DS92LV1212A is designed to be used with the DS92LV1021
Bus LVDS Serializer. The DS92LV1212A receives a Bus
LVDS serial data stream and transforms it into a 10-bit wide
parallel data bus and separate clock. The reduced cable,
PCB trace count and connector size saves cost and makes
PCB layout easier. Clock-to-data and data-to-data skews are
eliminated since one input receives both clock and data bits
serially. The powerdown pin is used to save power by reduc-
ing the supply current when the device is not in use. The
Deserializer will establish lock to a synchronization pattern
within specified lock times but it can also lock to a data
stream without SYNC patterns.
<
@
n Chipset (Tx + Rx) power consumption 300mW (typ)
40MHz
n Single differential pair eliminates multi-channel skew
n 400 Mbps serial Bus LVDS bandwidth (at 40 MHz clock)
n 10-bit parallel interface for 1 byte data plus 2 control bits
or UTOPIA I Interface
n Synchronization mode and LOCK indicator
n Flow-through pinout for easy PCB layout
n High impedance on receiver inputs when power is off
n Programmable edge trigger on clock
n Footprint compatible with DS92LV1210
n Small 28-lead SSOP package-MSA
Block Diagram
DS101387-1
TRI-STATE® is a registered trademark of National Semiconductor Corporation.
© 2000 National Semiconductor Corporation
DS101387
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Block Diagram (Continued)
Application
DS101387-2
Functional Description
Data Transfer
The DS92LV1212 is a 10-bit Deserializer chip designed to
receive data over heavily loaded differential backplanes at
clock speeds from 16 MHz to 40 MHz. It may also be used to
receive data over Unshielded Twisted Pair (UTP) cable.
After initialization, the Serializer will accept data from inputs
DIN0–DIN9. The Serializer uses the TCLK input to latch
incoming Data. The TCLK_R/F pin selects which edge the
Serializer uses to strobe incoming data. TCLK_R/F high
selects the rising edge for clocking data and low selects the
falling edge. If either of the SYNC inputs is high for 5*TCLK
cycles, the data at DIN0-DIN9 is ignored regardless of clock
edge.
The chip has three active states of operation: Initialization,
Data Transfer, and Resynchronization; and two passive
states: Powerdown and TRI-STATE®.
The following sections describe each operation of the active
and passive states.
After determining which clock edge to use, a start and stop
bit, appended internally, frame the data bits in the register.
The start bit is always high and the stop bit is always low.
The start and stop bits function as the embedded clock bits
in the serial stream.
Initialization
Before data can be transferred, the Deserializer must be
initialized. The Deserializer should be powered up with the
PWRDN pin held low. After VCC stabilizes, the PWRDN pin
can be forced high. The Deserializer is ready to lock to the
incoming data stream.
Serialized data and clock bits (10+2 bits) are received at 12
times the TCLK frequency. For example, if TCLK is 40 MHz,
the serial rate is 40 x 12 = 480 Mega bits per second. Since
only 10 bits are from input data, the serial “payload” rate is
10 times the TCLK frequency. For instance, if TCLK = 40
MHz, the payload data rate is 40 x 10 = 400 Mbps. TCLK is
provided by the data source and must be in the range 16
MHz to 40 MHz nominal.
Step 1: When you apply VCC to the Deserializer, the respec-
tive outputs are held in TRI-STATE and internal circuitry is
disabled by on-chip power-on circuitry. When VCC reaches
VCC OK (2.5V), the PLL is ready to lock to incoming data or
synchronization patterns. You must apply the local clock to
the REFCLK pin.
The LOCK pin on the Deserializer is driven low when it is
synchronized with the Serializer. The Deserializer locks to
the embedded clock and uses it to recover the serialized
data. ROUT data is valid when LOCK is low. Otherwise,
ROUT0–ROUT9 is invalid.
The Deserializer LOCK output will remain high while its PLL
locks to incoming data or to SYNC patterns on the inputs.
Step 2: The Deserializer PLL must synchronize to the Seri-
alizer to complete the initialization. The Deserializer will lock
to non-repetitive data patterns; however, the transmission of
SYNC patterns to the Deserializer enables the Deserializer
to lock to the Serializer signal within a specified time. See
Figure 7.
The ROUT0-ROUT9 pins use the RCLK pin as the reference
to data. The polarity of the RCLK edge is controlled by the
RCLK_R/F input. See Figure 5.
ROUT(0-9), LOCK and RCLK outputs will drive a minimum
of three CMOS input gates (15 pF load) with 40 MHz clock.
The user’s application determines control of the SYNC1 and
SYNC2 pins. One recommendation is a direct feedback loop
from the LOCK pin. Under all circumstances, the Serializer
stops sending SYNC patterns after both SYNC inputs return
low.
Resynchronization
When the Deserializer PLL locks to the embedded clock
edge, the Deserializer LOCK pin asserts a low. If the Dese-
rializer loses lock, the LOCK pin output will go high and the
outputs (including RCLK) will enter TRI-STATE.
When the Deserializer detects edge transitions at the Bus
LVDS input, it will attempt to lock to the embedded clock
information. When the Deserializer locks to the Bus LVDS
clock, the LOCK output will go low. When LOCK is low, the
Deserializer outputs represent incoming Bus LVDS data.
The user’s system monitors the LOCK pin to detect a loss of
synchronization. Upon detection, the system can arrange to
pulse the Serializer SYNC1 or SYNC2 pin to resynchronize.
Multiple resynchronization approaches are possible. One
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2
Resynchronization (Continued)
Powerdown
When no data transfer occurs, you can use the Powerdown
state. The Serializer and Deserializer use the Powerdown
state, a low power sleep mode, to reduce power consump-
tion. The Deserializer enters Powerdown when you drive
PWRDN and REN low. The Serializer enters Powerdown
when you drive PWRDN low. In Powerdown, the PLL stops
and the outputs enterTRI-STATE, which disables load cur-
rent and reduces supply current to the milliampere range. To
exit Powerdown, you must drive the PWRDN pin high.
recommendation is to provide a feedback loop using the
LOCK pin itself to control the sync request of the Serializer
(SYNC1 or SYNC2). Dual SYNC pins are provided for mul-
tiple control in a multi-drop application. Sending sync pat-
terns for resynchronization is desirable when lock times
within a specific time are critical. However, the Deserializer
can lock to random data, which is discussed in the next
section.
Before valid data exchanges between the Serializer and
Deserializer, you must reinitialize and resynchronize the de-
vices to each other. Initialization of the Serializer takes 510
TCLK cycles. The Deserializer will initialize and assert LOCK
high until lock to the Bus LVDS clock occurs.
Random Lock Initialization and
Resynchronization
The initialization and resynchronization methods described
in their respective sections are the fastest ways to establish
the link between the Serializer and Deserializer. However,
the DS92LV1212A can attain lock to a data stream without
requiring the Serializer to send special SYNC patterns. This
allows the DS92LV1212A to operate in “open-loop” applica-
tions. Equally important is the Deserializer’s ability to support
hot insertion into a running backplane. In the open loop or
hot insertion case, we assume the data stream is essentially
random. Therefore, because lock time varies due to data
stream characteristics, we cannot possibly predict exact lock
time. The primary constraint on “random” lock time is the
initial phase relation between the incoming data and the
REFCLK when the Deserializer powers up. As described in
the next paragraph, the data contained in the data stream
can also affect lock time.
TRI-STATE
The Serializer enters TRI-STATE when the DEN pin is driven
low. This puts both driver output pins (DO+ and DO−) into
TRI-STATE. When you drive DEN high, the Serializer returns
to the previous state, as long as all other control pins remain
static (SYNC1, SYNC2, PWRDN, TCLK_R/F).
When you drive the REN pin low, the Deserializer enters
TRI-STATE. Consequently, the receiver output pins
(ROUT0–ROUT9) and RCLK will enter TRI-STATE. The
LOCK output remains active, reflecting the state of the PLL.
If a specific pattern is repetitive, the Deserializer could enter
“false lock” - falsely recognizing the data pattern as the
clocking bits. We refer to such a pattern as a repetitive
multi-transition, RMT. This occurs when more than one
Low-High transition takes place in a clock cycle over multiple
cycles. This occurs when any bit, except DIN 9, is held at a
low state and the adjacent bit is held high, creating a 0-1
transition. In the worst case, the Deserializer could become
locked to the data pattern rather than the clock. Circuitry
within the DS92LV1212A can detect that the possibility of
“false lock” exists. The circuitry accomplishes this by detect-
ing more than one potential position for clocking bits. Upon
detection, the circuitry will prevent the LOCK output from
becoming active until the potential “false lock” pattern
changes. The false lock detect circuitry expects the data will
eventually change, causing the Deserializer to lose lock to
the data pattern and then continue searching for clock bits in
the serial data stream. Graphical representations of RMT are
shown on the following page. Please note that RMT only
applies to bits DIN0-DIN8.
3
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RMT Patterns
DS101387-23
DS101387-24
DIN0 Held Low-DIN1 Held High Creates an RMT Pattern
DIN4 Held Low-DIN5 Held High Creates an RMT Pattern
DS101387-25
DIN8 Held Low-DIN9 Held High Creates an RMT Pattern
Order Numbers
Function
NSID
Package
MSA28
MSA28
DS92LV1021TMSA
DS92LV1212AMSA
Serializer
Deserializer
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Package Derating:
28L SSOP
10.3mW/˚C above +25˚C
>
ESD Rating (HBM)
2kV
Supply Voltage (VCC
)
−0.3V to +4V
−0.3V to (VCC +0.3V)
−0.3V to (VCC +0.3V)
Recommended Operating
Conditions
CMOS/TTL Input Voltage
CMOS/TTL Output Voltage
Bus LVDS Receiver Input
Voltage
Min
Nom Max Units
−0.3V to +3.9V
+150˚C
Supply Voltage (VCC
)
3.0
3.3
3.6
+85
2.4
V
˚C
V
Junction Temperature
Storage Temperature
Lead Temperature
Operating Free Air
Temperature (TA)
−65˚C to +150˚C
−40
0
+25
Receiver Input Range
(Soldering, 4 seconds)
+260˚C
Maximum Package Power Dissipation Capacity
Supply Noise Voltage
100 mVP-P
(VCC
)
@
25˚C Package:
28L SSOP
1.27 W
Electrical Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
DESERIALIZER LVCMOS/LVTTL DC SPECIFICATIONS (apply to pins PWRDN, RCLK_R/ F, REN, REFCLK = inputs; apply to
pins ROUT, RCLK, LOCK = outputs)
VIH
VIL
High Level Input Voltage
Low Level Input Voltage
Input Clamp Voltage
2.0
VCC
0.8
V
V
GND
VCL
IIN
ICL = −18 mA
−0.62
−1.5
+15
VCC
0.5
V
±
Input Current
VIN = 0V or 3.6V
IOH = −9 mA
−10
2.1
2
µA
V
VOH
VOL
IOS
IOZ
High Level Output Voltage
Low Level Output Voltage
Output Short Circuit Current
TRI-STATE Output Current
2.93
0.33
−38
IOL = 9 mA
GND
−15
−10
V
VOUT = 0V
−85
+10
mA
µA
±
PWRDN or REN = 0.8V, VOUT = 0V or VCC
0.4
DESERIALIZER Bus LVDS DC SPECIFICATIONS (apply to pins RI+ and RI−)
VTH
VTL
IIN
Differential Threshold High
Voltage
VCM = +1.1V
+6
+50
mV
mV
Differential Threshold Low
Voltage
−50
−12
±
Input Current
VIN = +2.4V, VCC = 3.6V or 0V
VIN = 0V, VCC = 3.6V or 0V
−10
−10
1
+15
+10
µA
µA
±
0.05
DESERIALIZER SUPPLY CURRENT (apply to pins DVCC and AVCC)
ICCR
Deserializer Supply Current
Worst Case
CL = 15 pF
Figure 1
f = 40 MHz
f = 16 MHz
58
30
75
45
mA
mA
ICCXR
Deserializer Supply Current
Powerdown
PWRDN = 0.8V, REN = 0.8V
0.36
1.0
mA
Deserializer Timing Requirements for REFCLK
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
tRFCP
tRFDC
fRef
Parameter
REFCLK Period
Conditions
Min
Typ
T
Max
Units
25
62.5
ns
%
REFCLK Duty Cycle
REFCLK Frequency
REFCLK Transition Time
50
tRCP
3
0.95/tRCP
1.05/tRCP
6
tRFTT
ns
5
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Deserializer Switching Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
Conditions
Pin/Freq.
Min
Typ
Max
Units
tRCP
Receiver out Clock
Period
Figure 3
tRCP = tTCP
RCLK
25
62.5
ns
tCLH
tCHL
tDD
CMOS/TTL Low-to-High
Transition Time
CL = 15 pF
Figure 2
Rout(0-9),
1.2
1.1
4
4
ns
CMOS/TTL High-to-Low
Transition Time
LOCK, RCLK
ns
ns
Deserializer Delay
Figure 4
All Temp./All Freq. 1.75*tRCP+ 1.25 1.75*tRCP+3.75 1.75*tRCP+6.25
Room Temp
1.75*tRCP+ 2.25 1.75*tRCP+3.75 1.75*tRCP+5.25
3.3V/40MHz
tROS
tROH
ROUT (0-9) Setup Data to Figure 5
RCLK
RCLK
0.4*tRCP
0.5*tRCP
ns
ns
ROUT (0-9) Hold Data to
RCLK
−0.4*tRCP
45
−0.5*tRCP
tRDC
tHZR
tLZR
RCLK Duty Cycle
50
55
%
ns
ns
ns
ns
HIGH to TRI-STATE Delay Figure 6
LOW to TRI-STATE Delay
TRI-STATE to HIGH Delay
TRI-STATE to LOW Delay
Deserializer PLL Lock Time Figure 7
Rout(0-9),
LOCK
4.2+0.5*tRCP
4.5+0.5*tRCP
6+0.5*tRCP
6.0+0.5*tRCP
10+tRCP
10+tRCP
12+tRCP
12+tRCP
tZHR
tZLR
tDSR1
16MHz
40MHz
4
10
3
µs
µs
from PWRDWN (with
SYNCPAT)
Figure 8
(Note 4)
1.31
tDSR2
Deserializer PLL Lock time
from SYNCPAT
16MHz
40MHz
1.2
5
1
µs
µs
0.47
tZHLK
tRNM
TRI-STATE to HIGH Delay
(Power-up)
LOCK
4.62
12
ns
Deserializer Noise Margin
Figure 9
(Note 5)
16 MHz
40 MHz
900
450
1100
730
ps
ps
Note 1: “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the devices
should be operated at these limits. The table of “Electrical Characteristics” specifies conditions of device operation.
Note 2: Typical values are given for V
= 3.3V and T = +25˚C.
A
CC
Note 3: Current into device pins is defined as positive. Current out of device pins is defined as negative. Voltages are referenced to ground except VOD, ∆VOD, VTH
and VTL which are differential voltages.
Note 4: For the purpose of specifying Deserializer PLL performance tDSR1 and tDSR2 are specified with the REFCLK running and stable, and specific conditions
of the incoming data stream (SYNCPATs). It is recommended that the Deserializer be initialized using either tDSR1 timing or tDSR2 timing. tDSR1 is the time required
for the Deserializer to indicate lock upon power-up or when leaving the power-down mode. Synchronization patterns should be sent to the device before initiating
either condition. tDSR2 is the time required to indicate lock for the powered-up and enabled Deserializer when the input (RI+ and RI-) conditions change from not
receiving data to receiving synchronization patterns (SYNCPATs).
Note 5: tRNM is a measure of how much phase noise (jitter) the Deserializer can tolerate in the incoming data stream before bit errors occur.
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AC Timing Diagrams and Test Circuits
DS101387-4
FIGURE 1. “Worst Case” Deserializer ICC Test Pattern
DS101387-6
FIGURE 2. Deserializer CMOS/TTL Output Load and Transition Times
DS101387-11
FIGURE 3. Serializer Delay
DS101387-12
FIGURE 4. Deserializer Delay
7
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AC Timing Diagrams and Test Circuits (Continued)
DS101387-13
Timing shown for RCLK_R/F = LOW
Duty Cycle (t
) =
RDC
FIGURE 5. Deserializer Setup and Hold Times
DS101387-14
FIGURE 6. Deserializer TRI-STATE Test Circuit and Timing
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AC Timing Diagrams and Test Circuits (Continued)
DS101387-15
FIGURE 7. Deserializer PLL Lock Times and PWRDN TRI-STATE Delays
DS101387-22
FIGURE 8. Deserializer PLL Lock Time from SyncPAT
9
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AC Timing Diagrams and Test Circuits (Continued)
DS101387-21
SW - Setup and Hold Time (Internal data sampling window)
t
t
- Serializer Output Bit Position Jitter
JIT
= Receiver Sampling Margin Time
RSM
FIGURE 9. Receiver Bus LVDS Input Skew Margin
The Deserializer noise margin is the amount of input jitter
(phase noise) that the Deserializer can tolerate and still
reliably receive data. Various environmental and systematic
factors include:
Application Information
Using the DS92LV1021 and DS92LV1212A
The Serializer and Deserializer chipset is an easy to use
transmitter and receiver pair that sends 10 bits of parallel
LVTTL data over a serial Bus LVDS link up to 660 Mbps. An
on-board PLL serializes the input data and embeds two clock
bits within the data stream. The Deserializer uses a separate
reference clock (REFCLK) and an onboard PLL to extract
the clock information from the incoming data stream and
then deserialize the data. The Deserializer monitors the
incoming clock information, determines lock status, and as-
serts the LOCK output high when loss of lock occurs.
Serializer: TCLK jitter, VCC noise (noise bandwidth and
out-of-band noise)
Media: ISI, Large VCM shifts
Deserializer: VCC noise
Recovering from LOCK Loss
In the case where the Deserializer loses lock during data
transmission, up to 3 cycles of data that were previously
received can be invalid. This is due to the delay in the lock
detection circuit. The lock detect circuit requires that invalid
clock information be received 4 times in a row to indicate
loss of lock. Since clock information has been lost, it is
possible that data was also lost during these cycles. There-
fore, after the Deserializer relocks to the incoming data
stream and the Deserializer LOCK pin goes low, at least
three previous data cycles should be suspect for bit errors.
Power Considerations
An all CMOS design of the Serializer and Deserializer makes
them inherently low power devices. In addition, the constant
current source nature of the Bus LVDS outputs minimizes
the slope of the speed vs. ICC curve of conventional CMOS
designs.
Powering Up the Deserializer
The Deserializer can relock to the incoming data stream by
making the Serializer resend SYNC patterns, as described
above, or by random locking, which can take more time,
depending on the data patterns being received.
The DS92LV1212A can be powered up at any time by fol-
lowing the proper sequence. The REFCLK input can be
running before the Deserializer powers up, and it must be
running in order for the Deserializer to lock to incoming data.
The Deserializer outputs will remain in TRI-STATE until the
Deserializer detects data transmission at its inputs and locks
to the incoming data stream.
Hot Insertion
All the BLVDS devices are hot pluggable if you follow a few
rules. When inserting, ensure the Ground pin(s) makes con-
tact first, then the VCC pin(s), and then the I/O pins. When
removing, the I/O pins should be unplugged first, then the
VCC, then the Ground. Random lock hot insertion is illus-
trated in Figure 10.
Transmitting Data
Once you power up the Serializer and Deserializer, they
must be phase locked to each other to transmit data. Phase
locking occurs when the Deserializer locks to incoming data
or when the Serializer sends patterns. The Serializer sends
SYNC patterns whenever the SYNC1 or SYNC2 inputs are
high. The LOCK output of the Deserializer remains high until
it has locked to the incoming data stream. Connecting the
LOCK output of the Deserializer to one of the SYNC inputs of
the Serializer will guarantee that enough SYNC patterns are
sent to achieve Deserializer lock.
PCB Considerations
The Bus LVDS Serializer and Deserializer should be placed
as close to the edge connector as possible. In multiple
Deserializer applications, the distance from the Deserializer
to the slot connector appears as a stub to the Serializer
driving the backplane traces. Longer stubs lower the imped-
ance of the bus, increase the load on the Serializer, and
lower the threshold margin at the Deserializers. Deserializer
devices should be placed much less than one inch from slot
connectors. Because transition times are very fast on the
Serializer Bus LVDS outputs, reducing stub lengths as much
as possible is the best method to ensure signal integrity.
The Deserializer can also lock to incoming data by simply
powering up the device and allowing the “random lock”
circuitry to find and lock to the data stream.
While the Deserializer LOCK output is low, data at the De-
serializer outputs (ROUT0-9) is valid, except for the specific
case of loss of lock during transmission which is further
discussed in the ’Recovering from LOCK Loss’ section be-
low.
Transmission Media
The Serializer and Deserializer can also be used in
point-to-point configuration of a backplane, through a PCB
trace, or through twisted pair cable. In point-to-point configu-
ration, the transmission media need only be terminated at
Noise Margin
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Using tDJIT and tRNM to Validate Signal Quality
Application Information (Continued)
The parameters tDJIT and tRNM can be used to generate an
eye pattern mask to validate signal quality in an actual
application or in simulation.
the receiver end. Please note that in point-to-point configu-
ration, the potential of offsetting the ground levels of the
Serializer vs. the Deserializer must be considered. Also, Bus
LVDS provides a +/− 1.2V common mode range at the
receiver inputs.
The parameter tDJIT measures the transmitter’s ability to
place data bits in the ideal position to be sampled by the
receiver. The typical tDJIT parameter of −80pS indicates that
the crossing point of the Tx data is 80pS ahead of the ideal
crossing point. The tDJIT(min) and tDJIT(max) parameters
specify the earliest and latest, repectively, time that a cross-
ing will occur relative to the ideal position.
Failsafe Biasing for the DS92LV1212A
The DS92LV1212A has an improved input threshold sensi-
tivity of +/− 50mV versus +/− 100mV for the DS92LV1210 or
DS92LV1212. This allows for greater differential noise mar-
gin in the DS92LV1212A. However, in cases where the
receiver input is not being actively driven, the increased
sensitivity of the DS92LV1212A can pickup noise as a signal
and cause unintentional locking . For example, this can
occur when the input cable is disconnected.
The parameter tRNM is calculated by first measuring how
much of the ideal bit the receiver needs to ensure correct
sampling. After determining this amount, what remains of the
ideal bit that is available for external sources of noise is
called tRNM. It is the offset from tDJIT(min or max) for the test
mask within the eye opening.
External resistors can be added to the receiver circuit board
to prevent noise pick-up. Typically, the non-inverting receiver
input is pulled up and the inverting receiver input is pulled
down by high value resistors. the pull-up and pull-down
resistors (R1 and R2) provide a current path through the
termination resistor (RL) which biases the receiver inputs
when they are not connected to an active driver. The value of
the pull-up and pull-down resistors should be chosen so that
enough current is drawn to provide a +15mV drop across the
termination resistor. Please see Figure 11 for the Failsafe
Biasing Setup.
The vertical limits of the mask are determined by the
DS92LV1212A receiver input threshold of +/− 50mV.
Please refer to the eye mask pattern of Figure 12 for a
graphic representation of tDJIT and tRNM
.
DS101387-26
The DS92LV1212A can be “Hot Inserted” into operating serial busses without interrupting bus communication. The random lock feature allows the
DS92LV1212A to synchronize to the bus traffic and receive data.
FIGURE 10. Random Lock Allows Hot Insertion into Serial Busses
DS101387-27
FIGURE 11. Failsafe Biasing Setup
11
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Application Information (Continued)
DS101387-28
Note: For the DS92LV1021, tDJIT(max) = 70pS and tDJIT(min) = −300pS
FIGURE 12. Using tDJIT and tRNM to Generate an Eye Pattern Mask and Validate SIgnal Quality
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Pin Diagram
DS92LV1212AMSA - Deserializer
DS101387-19
Deserializer Pin Description
Pin Name
I/O
No.
Description
±
ROUT
O
15–19,
24–28
Data Output. 9 mA CMOS level outputs.
RCLK_R/F
I
2
Recovered Clock Rising/Falling strobe select. TTL level input.
Selects RCLK active edge for strobing of ROUT data. High
selects rising edge. Low selects falling edge.
RI+
I
I
I
5
6
7
+ Serial Data Input. Non-inverting Bus LVDS differential input.
− Serial Data Input. Inverting Bus LVDS differential input.
RI−
PWRDN
Powerdown. TTL level input. PWRDN driven low shuts down the
PLL.
LOCK
O
10
LOCK goes low when the Deserializer PLL locks onto the
embedded clock edge. CMOS level output. Totem pole output
structure, does not directly support wire OR connection.
RCLK
REN
O
I
9
8
Recovered Clock. Parallel data rate clock recovered from
embedded clock. Used to strobe ROUT, CMOS level output.
Output Enable. TTL level input. TRI-STATEs ROUT0–ROUT9,
LOCK and RCLK when driven low.
DVCC
DGND
AVCC
I
I
I
I
I
21, 23
14, 20, 22
4, 11
Digital Circuit power supply.
Digital Circuit ground.
Analog power supply (PLL and Analog Circuits).
Analog ground (PLL and Analog Circuits).
AGND
REFCLK
1, 12, 13
3
Use this pin to supply a REFCLK signal for the internal PLL
frequency.
13
www.national.com
Truth Table
INPUTS
OUTPUTS
PWRDN
REN
H
ROUT [0:9]
LOCK
RCLK
H
H
L
Z
Active
Z
H
L
Z
Active
Z
H
X
Z
H
L
Z
Active
Z
1) LOCK Active indicates the LOCK output will reflect the state of the Deserializer with regard to the selected data stream.
2) RCLK Active indicates the RCLK will be running if the Deserializer is locked. The Timing of RCLK with respect to ROUT is determined by RCLK_R/F.
3) ROUT and RCLK are TRI-STATED when LOCK is asserted High.
www.national.com
14
Physical Dimensions inches (millimeters) unless otherwise noted
Note: Package Dimensions are in millimeters only.
Order Number DS92LV1212AMSA
NS Package Number MSA28
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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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相关型号：
DS92LV1021TMSA
DS92LV1212A 16-40 MHz 10-Bit Bus LVDS Random Lock Deserializer with Embedded Clock Recovery
TI
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