SCAN921025H, SCAN921226H
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SNLS185C – OCTOBER 2004 – REVISED MAY 2013
SCAN921025H and SCAN921226H High Temperature 20-80 MHz 10 Bit Bus LVDS SerDes
with IEEE 1149.1 (JTAG) and at-speed BIST
Check for Samples: SCAN921025H, SCAN921226H
FEATURES
DESCRIPTION
•
•
The SCAN921025H transforms a 10-bit wide parallel
LVCMOS/LVTTL data bus into a single high speed
Bus LVDS serial data stream with embedded clock.
The SCAN921226H receives the Bus LVDS serial
data stream and transforms it back into a 10-bit wide
parallel data bus and recovers parallel clock.
1
2
•
•
•
•
•
•
•
•
•
•
•
High Temperature Operation to 125°C
IEEE 1149.1 (JTAG) Compliant and At-Speed
BIST Test Mode
Clock Recovery from PLL Lock to Random
Data Patterns
Ensured Transition Every Data Transfer Cycle
Chipset (Tx + Rx) Power Consumption < 600
mW (Typ) @ 80 MHz
Single Differential Pair Eliminates MultiChannel Skew
800 Mbps Serial Bus LVDS Data Rate (at 80
MHz Clock)
10-bit Parallel Interface for 1 Byte Data Plus 2
Control Bits
Synchronization Mode and LOCK Indicator
Programmable Edge Trigger on Clock
High Impedance on Receiver Inputs When
Power is Off
Bus LVDS Serial Output Rated for 27Ω Load
Small 49-Lead NFBGA Package
APPLICATIONS
•
•
•
Automotive
Industrial
Military/Aerospace
Both devices are compliant with IEEE 1149.1
Standard for Boundary Scan Test. IEEE 1149.1
features provide the design or test engineer access
via a standard Test Access Port (TAP) to the
backplane or cable interconnects and the ability to
verify differential signal integrity. The pair of devices
also features an at-speed BIST mode which allows
the interconnects between the Serializer and
Deserializer to be verified at-speed.
The SCAN921025H transmits data over backplanes
or cable. The single differential pair data path makes
PCB design easier. In addition, the reduced cable,
PCB trace count, and connector size tremendously
reduce cost. Since one output transmits clock and
data bits serially, it eliminates clock-to-data and datato-data skew. The powerdown pin saves power by
reducing supply current when not using either device.
Upon power up of the Serializer, you can choose to
activate synchronization mode or allow the
Deserializer to use the synchronization-to-randomdata feature. By using the synchronization mode, the
Deserializer will establish lock to a signal within
specified lock times. In addition, the embedded clock
ensures a transition on the bus every 12-bit cycle.
This eliminates transmission errors due to charged
cable conditions. Furthermore, you may put the
SCAN921025H output pins into tri-state to achieve a
high impedance state. The PLL can lock to
frequencies between 20 MHz and 80 MHz.
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004–2013, Texas Instruments Incorporated
SCAN921025H, SCAN921226H
SNLS185C – OCTOBER 2004 – REVISED MAY 2013
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Block Diagram
Figure 1. Application
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Functional Description
The SCAN921025H and SCAN921226H are a 10-bit Serializer and Deserializer chipset designed to transmit
data over differential backplanes at clock speeds from 20 to 80 MHz. The chipset is also capable of driving data
over Unshielded Twisted Pair (UTP) cable.
The chipset has three active states of operation: Initialization, Data Transfer, and Resynchronization; and two
passive states: Powerdown and Tri-state. In addition to the active and passive states, there are also test modes
for JTAG access and at-speed BIST.
The following sections describe each operation and passive state and the test modes.
Initialization
Initialization of both devices must occur before data transmission begins. Initialization refers to synchronization of
the Serializer and Deserializer PLL's to local clocks, which may be the same or separate. Afterwards,
synchronization of the Deserializer to Serializer occurs.
Step 1: When you apply VCC to both Serializer and/or Deserializer, the respective outputs enter tri-state, and onchip power-on circuitry disables internal circuitry. When VCC reaches VCCOK (2.5V) the PLL in each device
begins locking to a local clock. For the Serializer, the local clock is the transmit clock (TCLK) provided by the
source ASIC or other device. For the Deserializer, you must apply a local clock to the REFCLK pin.
The Serializer outputs remain in tri-state while the PLL locks to the TCLK. After locking to TCLK, the Serializer is
now ready to send data or SYNC patterns, depending on the levels of the SYNC1 and SYNC2 inputs or a data
stream. The SYNC pattern sent by the Serializer consists of six ones and six zeros switching at the input clock
rate.
Note that the Deserializer LOCK output will remain high while its PLL locks to the incoming data or to SYNC
patterns on the input.
Step 2: The Deserializer PLL must synchronize to the Serializer to complete initialization. The Deserializer will
lock to non-repetitive data patterns. However, the transmission of SYNC patterns enables the Deserializer to lock
to the Serializer signal within a specified time. See Figure 17.
The user's application determines control of the SYNC1 and SYNC 2 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.
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.
Data Transfer
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.
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.
The Serializer transmits serialized data and clock bits (10+2 bits) from the serial data output (DO±) at 12 times
the TCLK frequency. For example, if TCLK is 80 MHz, the serial rate is 80 × 12 = 960 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 = 80 MHz, the payload data rate is 80 × 10 = 800 Mbps. The data source provides TCLK and must be in
the range of 20 MHz to 80 MHz nominal.
The Serializer outputs (DO±) can drive a point-to-point connection or in limited multi-point or multi-drop
backplanes. The outputs transmit data when the enable pin (DEN) is high, PWRDN = high, and SYNC1 and
SYNC2 are low. When DEN is driven low, the Serializer output pins will enter tri-state.
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When the Deserializer synchronizes to the Serializer, the LOCK pin is low. 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 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 14.
ROUT(0-9), LOCK and RCLK outputs will drive a maximum of three CMOS input gates (15 pF load) with a 80
MHz clock.
Resynchronization
When the Deserializer PLL locks to the embedded clock edge, the Deserializer LOCK pin asserts a low. If the
Deserializer loses lock, the LOCK pin output will go high and the outputs (including RCLK) will enter tri-state.
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 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 multiple control in a multi-drop
application. Sending sync patterns 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.
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 SCAN921226H can attain lock to a data
stream without requiring the Serializer to send special SYNC patterns. This allows the SCAN921226H to operate
in “open-loop” applications. 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.
However, please see Table 1 for some general random lock times under specific conditions. The primary
constraint on the “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.
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 SCAN921226H
can detect that the possibility of “false lock” exists. The circuitry accomplishes this by detecting 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 in Figure 2. Please note that RMT
only applies to bits DIN0-DIN8.
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 consumption. 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 enter tri-state, which disables load current and reduces supply
current to the milliampere range. To exit Powerdown, you must drive the PWRDN pin high.
Before valid data exchanges between the Serializer and Deserializer, you must reinitialize and resynchronize the
devices 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.
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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.
Table 1.
Random Lock Times for the SCAN921226H (1)
80 MHz
Units
Maximum
18
μs
Mean
3.0
μs
0.43
μs
Minimum
PRBS 215, VCC = 3.3V
Conditions:
(1)
Difference in lock times are due to different starting points in the data pattern with multiple parts.
Test Modes
In addition to the IEEE 1149.1 test access to the digital TTL pins, the SCAN921025H and SCAN921226H have
two instructions to test the LVDS interconnects. The first is EXTEST. This is implemented at LVDS levels and is
only intended as a go no-go test (e.g. missing cables). The second method is the RUNBIST instruction. It is an
"at-system-speed" interconnect test. It is executed in approximately 28mS with a system clock speed of 80MHz.
There are two bits in the RX BIST data register for notification of PASS/FAIL and TEST_COMPLETE. Pass
indicates that the BER (Bit-Error-Rate) is better than 10-7.
An important detail is that once both devices have the RUNBIST instruction loaded into their respective
instruction registers, both devices must move into the RTI state within 4K system clocks (At a SCLK of 66Mhz
and TCK of 1MHz this allows for 66 TCK cycles). This is not a concern when both devices are on the same scan
chain or LSP, however, it can be a problem with some multi-drop devices. This test mode has been simulated
and verified using TI's SCANSTA111.
DIN0 Held Low-DIN1 Held High Creates an RMT Pattern
DIN4 Held Low-DIN5 Held High Creates an RMT Pattern
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DIN8 Held Low-DIN9 Held High Creates an RMT Pattern
Figure 2. RMT Patterns Seen on the Bus LVDS Serial Output
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
Absolute Maximum Ratings (1)
−0.3V to +4V
Supply Voltage (VCC)
LVCMOS/LVTTL Input Voltage
−0.3V to (VCC +0.3V)
LVCMOS/LVTTL Output Voltage
−0.3V to (VCC +0.3V)
Bus LVDS Receiver Input Voltage
−0.3V to +3.9V
Bus LVDS Driver Output Voltage
−0.3V to +3.9V
Bus LVDS Output Short Circuit Duration
10mS
Junction Temperature
+150°C
−65°C to +150°C
Storage Temperature
Lead Temperature
(Soldering, 4 seconds)
+220°C
Maximum Package Power Dissipation Capacity
@ 25°C Package:
49L NFBGA
1.47 W
Package Derating:
49L NFBGA
11.8 mW/°C above +25°C
θja
85°C/W
ESD Rating
(1)
HBM
>2kV
MM
> 250V
Absolute Maximum Ratings are those values beyond which the safety of the device cannot be ensured. 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.
Recommended Operating Conditions
Min
Nom
Max
Supply Voltage (VCC)
3.0
3.3
3.6
V
Operating Free Air Temperature (TA)
−40
+25
+125
°C
Receiver Input Range
0
Supply Noise Voltage (VCC)
6
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Units
2.4
V
100
mVP-P
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Electrical Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
SERIALIZER LVCMOS/LVTTL DC SPECIFICATIONS (apply to DIN0-9, TCLK, PWRDN, TCLK_R/F, SYNC1, SYNC2, DEN)
VIH
High Level Input Voltage
2.0
VCC
V
VIL
Low Level Input Voltage
GND
0.8
V
VCL
Input Clamp Voltage
ICL = −18 mA
-0.86
−1.5
V
IIN
Input Current
VIN = 0V or 3.6V
±1
+10
μA
−10
DESERIALIZER LVCMOS/LVTTL DC SPECIFICATIONS (apply to pins PWRDN, RCLK_R/ F, REN, REFCLK = inputs; apply to pins
ROUT, RCLK, LOCK = outputs)
VIH
High Level Input Voltage
2.0
VCC
V
VIL
Low Level Input Voltage
GND
0.8
V
VCL
Input Clamp Voltage
ICL = −18 mA
IIN
Input Current
VIN = 0V or 3.6V
VOH
High Level Output Voltage
IOH = −9 mA
VOL
Low Level Output Voltage
IOL = 9 mA
IOS
Output Short Circuit Current
VOUT = 0V
IOZ
Tri-state Output Current
PWRDN or REN = 0.8V, VOUT = 0V or VCC
−0.62
−1.5
V
±1
+15
μA
2.2
3.0
VCC
V
GND
0.25
0.5
V
−15
−47
−85
mA
−10
±0.1
+10
μA
200
290
1.05
1.1
1.3
V
4.8
35
mV
−56
−90
mA
−10
SERIALIZER Bus LVDS DC SPECIFICATIONS (apply to pins DO+ and DO−)
VOD
Output Differential Voltage
(DO+)–(DO−)
ΔVOD
Output Differential Voltage Unbalance
VOS
Offset Voltage
ΔVOS
Offset Voltage Unbalance
IOS
Output Short Circuit Current
D0 = 0V, DIN = High,PWRDN and DEN =
2.4V
IOZ
Tri-state Output Current
PWRDN or DEN = 0.8V, DO = 0V or VCC
−10
±1
+10
μA
IOX
Power-Off Output Current
VCC = 0V, DO=0V or 3.6V
−20
±1
+30
μA
+6
+50
mV
−50
−12
RL = 27Ω, Figure 18
mV
35
mV
DESERIALIZER Bus LVDS DC SPECIFICATIONS (apply to pins RI+ and RI−)
VTH
Differential Threshold High Voltage
VTL
Differential Threshold Low Voltage
IIN
Input Current
VCM = +1.1V
mV
VIN = +2.4V, VCC = 3.6V or 0V
−10
±1
+10
μA
VIN = 0V, VCC = 3.6V or 0V
−10
±0.05
+10
μA
SERIALIZER SUPPLY CURRENT (apply to pins DVCC and AVCC)
ICCD
ICCXD
Serializer Supply Current
RL = 27Ω
f = 20 MHz
45
60
mA
Worst Case
Figure 3
f = 80 MHz
90
105
mA
Serializer Supply Current Powerdown
PWRDN = 0.8V, f = 80MHz
0.2
2.0
mA
DESERIALIZER SUPPLY CURRENT (apply to pins DVCC and AVCC)
ICCR
ICCXR
Deserializer Supply Current
CL = 15 pF
f = 20 MHz
50
75
mA
Worst Case
Figure 4
f = 80 MHz
100
120
mA
Deserializer Supply Current
Powerdown
PWRDN = 0.8V, REN = 0.8V
0.36
1.0
mA
SCAN CIRCUITRY DC SPECIFICATIONS, SERIALIZER AND DESERIALIZER (applies to SCAN pins as noted)
VIH
High Level Input Voltage
VCC = 3.0 to 3.6V, pins TCK, TMS, TDI, and
TRST
2.0
VCC
V
VIL
Low Level Input Voltage
VCC = 3.0 to 3.6V, pins TCK, TMS, TDI, and
TRST
GND
0.8
V
VCL
Input Clamp Voltage
VCC = 3.0V, ICL = −18 mA, pins TCK, TMS,
TDI, and TRST
−0.85
−1.5
V
IIH
Input Current
VCC = 3.6V, VIN = 3.6V, pins TCK, TMS, TDI,
and TRST
1
+10
μA
IIL
Input Current
VCC = 3.6V, VIN = 0.0V, TCK Input
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Electrical Characteristics (continued)
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
IILR
Input Current
VCC = 3.6V, VIN = 0V, pins TMS, TDI, and
TRST
-20
-10
VOH
High Level Output Voltage
VCC = 3.0V, IOH = −12 mA, TDO output
2.2
2.6
VOL
Low Level Output Voltage
VCC = 3.0V, IOL = 12 mA, TDO output
IOS
Output Short Circuit Current
VCC = 3.6V, VOUT = 0.0V, TDO output
IOZ
Tri-state Output Current
PWRDN or REN = 0.8V, VOUT = 0V or VCC
Max
Units
μA
V
0.3
0.5
V
-15
-90
-120
mA
−10
0
+10
μA
Serializer Timing Requirements for TCLK
Over recommended operating supply and temperature ranges unless otherwise specified.
Min
Typ
Max
Units
tTCP
Symbol
Transmit Clock Period
Parameter
Conditions
12.5
T
50.0
ns
tTCIH
Transmit Clock High Time
0.4T
0.5T
0.6T
ns
tTCIL
Transmit Clock Low Time
0.4T
0.5T
0.6T
ns
tCLKT
TCLK Input Transition Time
3
6
ns
tJIT
TCLK Input Jitter
150
ps
(RMS)
Serializer Switching Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
tLLHT
Bus LVDS Low-to-High
Transition Time
tLHLT
Bus LVDS High-to-Low
Transition Time
tDIS
DIN (0-9) Setup to TCLK
tHZD
DO ± HIGH to
Tri-state Delay
tLZD
DO ± LOW to Tri-state
Delay
tZHD
DO ± Tri-state to HIGH
Delay
tZLD
DO ± Tri-state to LOW
Delay
tSPW
SYNC Pulse Width
tPLD
tSD
tRJIT
(1)
(2)
(3)
8
Min
RL = 27Ω
CL=10pF to GND
Figure 5 (1)
RL = 27Ω,
CL=10pF to GND
DIN (0-9) Hold from TCLK Figure 8
tDIH
tDJIT
Conditions
Typ
Max
Units
0.2
0.4
ns
0.25
0.4
ns
0
ns
4.0
ns
RL = 27Ω,
CL=10pF to GND
Figure 9 (2)
Serializer PLL Lock Time
510*tTCP
Serializer Delay
RL = 27Ω, Figure 12
tTCP+ 1.0
Random Jitter
RL = 27Ω,
CL=10pF
to GND (3)
10
ns
3
10
ns
5
10
ns
6.5
10
ns
5*tTCP
RL = 27Ω
Figure 11
Deterministic Jitter
3
20MHz
80MHz
ns
tTCP+ 2.5
-330
-130
513*tTCP
ns
tTCP+ 3.5
ns
140
ps
-40
+60
ps
6
10
ps (RMS)
tLLHT and tLHLT specifications are Guaranteed By Design (GBD) using statistical analysis.
Because the Serializer is in tri-state mode, the Deserializer will lose PLL lock and have to resynchronize before data transfer.
tDJIT specifications are Guaranteed By Design using statistical analysis.
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Deserializer Timing Requirements for REFCLK
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
tRFCP
REFCLK Period
12.5
T
50.0
ns
tRFDC
REFCLK Duty Cycle
30
50
70
%
tRFCP /
tTCP
Ratio of REFCLK to TCLK
95
1
105
tRFTT
REFCLK Transition Time
3
6
ns
Deserializer Switching Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
tRCP
Receiver out Clock
Period
tCLH
CMOS/TTL Low-to-High
Transition Time
tCHL
CMOS/TTL High-to-Low
Transition Time
tDD
Conditions
Pin/Freq.
Min
tRCP = tTCP
Figure 12
RCLK
12.5
CL = 15 pF
Figure 6
Rout(0-9),
LOCK,
RCLK
All Temp, All Freq
Deserializer Delay
Figure 13
Units
50.0
ns
1.2
4
ns
1.1
4
ns
1.75*tRCP+1.25
1.75*tRCP+5.0
1.75*tRCP+8.5
ns
20MHz
1.75*tRCP+2.25
1.75*tRCP+5.0
1.75*tRCP+8.0
ns
Room Temp, 3.3V
80MHz
1.75*tRCP+2.25
1.75*tRCP+5.0
1.75*tRCP+8.0
ns
RCLK
20MHz
0.4*tRCP
0.5*tRCP
ns
RCLK
80MHz
0.35*tRCP
0.5*tRCP
ns
20MHz
-0.4*tRCP
-0.5*tRCP
ns
80MHz
-0.35*tRCP
-0.5*tRCP
45
50
55
%
2.8
10
ns
2.8
10
ns
4.2
10
ns
4.2
10
ns
20MHz
1.7
3.5
μs
80MHz
1.0
2.5
μs
20MHz
0.65
1.5
μs
80MHz
0.29
0.8
μs
3.7
12
ns
ROUT Data Valid before
RCLK
Figure 14
tROH
ROUT Data Valid after
RCLK
Figure 14
tRDC
RCLK Duty Cycle
tHZR
HIGH to Tri-state Delay
tLZR
LOW to Tri-state Delay
tZHR
Tri-state to HIGH Delay
tZLR
Tri-state to LOW Delay
tDSR1
Deserializer PLL Lock
Time from PWRDWN
(with SYNCPAT)
Deserializer PLL Lock
time from SYNCPAT
Max
Room Temp, 3.3V
tROS
tDSR2
Typ
Figure 15
Figure 16
Figure 17 (1)
Rout(0-9)
tZHLK
Tri-state to HIGH Delay
(power-up)
LOCK
tRNMI-R
VCC = 3.15 to 3.6V
Ideal Noise Margin Right
VCC = 3.0V
Figure 21
80MHz
+335
+215
20MHz
tRNMI-L
VCC = 3.15 to 3.6V
Ideal Noise Margin Left
Figure 21
VCC = 3.0V
80MHz
20MHz
(1)
ns
+1
-395
ps
ns
ps
-520
-1
ns
For the purpose of specifying deserializer PLL performance, tDSR1 and tDSR2 are specified with the REFCLK running and stable, and
with specific conditions for the incoming data stream (SYNCPATs). It is recommended that the derserializer 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 powerdown 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).
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SCAN Circuitry Timing Requirements
Min
Typ
fMAX
Symbol
Maximum TCK Clock
Frequency
25.0
50.0
tS
TDI to TCK, H or L
1.0
ns
tH
TDI to TCK, H or L
2.0
ns
tS
TMS to TCK, H or L
2.5
ns
tH
TMS to TCK, H or L
1.5
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
10
Parameter
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Conditions
RL = 500Ω, CL = 35 pF
Max
Units
MHz
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AC Timing Diagrams and Test Circuits
Figure 3. “Worst Case” Serializer ICC Test Pattern
Figure 4. “Worst Case” Deserializer ICC Test Pattern
Figure 5. Serializer Bus LVDS Output Load and Transition Times
Figure 6. Deserializer CMOS/TTL Output Load and Transition Times
Figure 7. Serializer Input Clock Transition Time
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Timing shown for TCLK_R/F = LOW
Figure 8. Serializer Setup/Hold Times
Figure 9. Serializer Tri-state Test Circuit and Timing
Figure 10. Serializer PLL Lock Time, and PWRDN Tri-state Delays
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Figure 11. SYNC Timing Delays
Figure 12. Serializer Delay
Figure 13. Deserializer Delay
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Timing shown for RCLK_R/F = LOW
Duty Cycle (tRDC) =
Figure 14. Deserializer Data Valid Out Times
Figure 15. Deserializer Tri-state Test Circuit and Timing
14
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Figure 16. Deserializer PLL Lock Times and PWRDN Tri-state Delays
Figure 17. Deserializer PLL Lock Time from SyncPAT
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VOD = (DO+)–(DO−).
Differential output signal is shown as (DO+)–(DO−), device in Data Transfer mode.
Figure 18. VOD Diagram
16
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APPLICATION INFORMATION
USING THE SCAN921025H AND SCAN921226H
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 800 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 asserts the LOCK output
high when loss of lock occurs.
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 SCAN921226H can be powered up at any time by following 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.
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 ensure that enough SYNC patterns are sent to
achieve Deserializer lock.
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 Deserializer 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 below.
NOISE 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:
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. Therefore, 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.
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.
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HOT INSERTION
All the BLVDS devices are hot pluggable if you follow a few rules. When inserting, ensure the Ground pin(s)
makes contact 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 illustrated in Figure 22.
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 impedance 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.
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 configuration, the transmission media need only be
terminated at the receiver end. Please note that in point-to-point configuration, 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.
FAILSAFE BIASING FOR THE SCAN921226H
The SCAN921226H has an improved input threshold sensitivity of +/− 50mV versus +/− 100mV for the
DS92LV1210 or DS92LV1212. This allows for greater differential noise margin in the SCAN921226H. However,
in cases where the receiver input is not being actively driven, the increased sensitivity of the SCAN921226H can
pickup noise as a signal and cause unintentional locking. For example, this can occur when the input cable is
disconnected.
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 19 for the Failsafe Biasing Setup.
USING tDJIT AND tRNM TO VALIDATE SIGNAL QUALITY
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. tRNM includes transmitter jitter.
Please refer to Figure 20 and Figure 21 for a graphic representation of tDJIT and tRNM. Also, for a more detailed
explanation of tRNM, please see the Application Note titled 'How to Validate BLVDS SER/DES Signal Integrity
Using an Eye Mask' (SNLA053).
The vertical limits of the mask are determined by the SCAN921226H receiver input threshold of +/− 50mV.
Figure 19. Failsafe Biasing Setup
18
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Figure 20. Deterministic Jitter and Ideal Bit Position
tRNMI-L is the ideal noise margin on the left of the figure, it is a negative value to indicate early with respect to ideal.
tRNMI-R is the ideal noise margin on the right of the above figure, it is a positive value to indicate late with respect to
ideal.
Figure 21. Ideal Deserializer Noise Margin (tRNMI) and Sampling Window
Figure 22. Random Lock Hot Insertion
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Pin Diagrams
Figure 23. SCAN921025HSM - Serializer (Top View)
Figure 24.
Figure 25. SCAN921226HSM - Deserializer (Top View)
20
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Serializer Pin Descriptions
Pin Name
I/O
Ball Id.
Description
DIN
I
TCLKR/F
I
G3
Transmit Clock Rising/Falling strobe select. LVTTL level input. Selects
TCLK active edge for strobing of DIN data. High selects rising edge. Low
selects falling edge.
DO+
O
D7
+ Serial Data Output. Non-inverting Bus LVDS differential output.
DO−
O
D5
− Serial Data Output. Inverting Bus LVDS differential output.
DEN
I
D6
Serial Data Output Enable. LVTTL level input. A low puts the Bus LVDS
outputs in tri-state.
PWRDN
I
C7
Powerdown. LVTTL level input. PWRDN driven low shuts down the PLL
and tri-states outputs putting the device into a low power sleep mode.
TCLK
I
E4
Transmit Clock. LVTTL level input. Input for 20MHz – 80MHz system clock.
SYNC
I
A4, B3
Assertion of SYNC (high) for at least 1024 synchronization symbols to be
transmitted on the Bus LVDS serial output. Synchronization symbols
continue to be sent if SYNC continues to be asserted. TTL level input. The
two SYNC pins are ORed.
DVCC
I
C3, C4, E5
DGND
I
A1, C2, F5, E6,
G4
Digital Circuit ground.
AVCC
I
A5, A6, B4, B7,
G5
Analog power supply (PLL and Analog Circuits).
AGND
I
B5, B6, C6, E7,
F7
Analog ground (PLL and Analog Circuits).
TDI
I
F1
Test Data Input to support IEEE 1149.1. There is an internal pullup resistor
that defaults this input to high per IEEE 1149.1.
TDO
O
G1
Test Data Output to support IEEE 1149.1
TMS
I
E3
Test Mode Select Input to support IEEE 1149.1. There is an internal pullup
resistor that defaults this input to high per IEEE 1149.1.
TCK
I
F3
Test Clock Input to support IEEE 1149.1
TRST
I
G2
Test Reset Input to support IEEE 1149.1. There is an internal pullup resistor
that defaults this input to high per IEEE 1149.1.
N/A
A2, A7, B2, C5,
D4, F6, G6, G7
N/C
A3, B1, C1, D1, Data Input. LVTTL levels inputs. Data on these pins are loaded into a 10-bit
D2, D3, E1, E2, input register.
F2, F4
Digital Circuit power supply.
Leave open circuit, do not connect
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Deserializer Pin Descriptions
Pin Name
I/O
Ball Id.
ROUT
O
A5, B4, B6, C4,
C7, D6, F5, F7,
G4, G5
RCLKR/F
I
B3
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
D2
+ Serial Data Input. Non-inverting Bus LVDS differential input.
RI−
I
C1
− Serial Data Input. Inverting Bus LVDS differential input.
PWRDN
I
D3
Powerdown. TTL level input. PWRDN driven low shuts down the PLL and
tri-states outputs putting the device into a low power sleep mode.
LOCK
O
E1
LOCK goes low when the Deserializer PLL locks onto the embedded clock
edge. CMOS level output. Totem pole output structure, does not directly
support wired OR connections.
RCLK
O
E2
Recovered Clock. Parallel data rate clock recovered from embedded clock.
Used to strobe ROUT, CMOS level output.
REN
I
D1
Output Enable. TTL level input. When driven low, tri-states ROUT0–ROUT9
and RCLK.
DVCC
I
A7, B7, C5, C6, Digital Circuit power supply.
D5
DGND
I
A1, A6, B5, D7,
E4, E7, G3
Digital Circuit ground.
AVCC
I
B1, C2, F1, F2,
G1
Analog power supply (PLL and Analog Circuits).
AGND
I
A4, B2, F3, F4,
G2
Analog ground (PLL and Analog Circuits).
REFCLK
I
A3
Use this pin to supply a REFCLK signal for the internal PLL frequency.
TDI
I
F6
Test Data Input to support IEEE 1149.1. There is an internal pullup resistor
that defaults this input to high per IEEE 1149.1.
TDO
O
G6
Test Data Output to support IEEE 1149.1
TMS
I
G7
Test Mode Select Input to support IEEE 1149.1. There is an internal pullup
resistor that defaults this input to high per IEEE 1149.1.
TCK
I
E5
Test Clock Input to support IEEE 1149.1
TRST
I
E6
Test Reset Input to support IEEE 1149.1. There is an internal pullup resistor
that defaults this input to high per IEEE 1149.1.
N/A
A2, C3, D4, E3
N/C
Description
Data Output. ±9 mA CMOS level outputs.
Leave open circuit, do not connect
SPACER
Deserializer Truth Table
INPUTS
PWRDN
H
(1)
(2)
(3)
(4)
22
(4)
OUTPUTS
REN
ROUT [0:9]
(1)
LOCK (2)
RCLK (3) (1)
H
Z
H
Z
H
H
Active
L
Active
L
X
Z
Z
Z
H
L
Z
Active
Z
ROUT and RCLK are tri-stated when LOCK is asserted High.
LOCK Active indicates the LOCK output will reflect the state of the Deserializer with regard to the selected data stream.
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.
During Power-up.
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SNLS185C – OCTOBER 2004 – REVISED MAY 2013
REVISION HISTORY
Changes from Revision B (May 2013) to Revision C
•
Page
Changed layout of National Data Sheet to TI format. ......................................................................................................... 22
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
(3)
Device Marking
(4/5)
(6)
SCAN921025HSM
NRND
NFBGA
NZA
49
416
Non-RoHS &
Non-Green
Call TI
Call TI
-40 to 125
SCAN921025
HSM
SCAN921025HSM/NOPB
ACTIVE
NFBGA
NZA
49
416
RoHS & Green
SNAGCU
Level-4-260C-72 HR
-40 to 125
SCAN921025
HSM
SCAN921025HSMX/NOPB
ACTIVE
NFBGA
NZA
49
2000
RoHS & Green
SNAGCU
Level-4-260C-72 HR
-40 to 125
SCAN921025
HSM
SCAN921226HSM
NRND
NFBGA
NZA
49
416
Non-RoHS &
Non-Green
Call TI
Call TI
-40 to 125
SCAN921226
HSM
SCAN921226HSM/NOPB
ACTIVE
NFBGA
NZA
49
416
RoHS & Green
SNAGCU
Level-4-260C-72 HR
-40 to 125
SCAN921226
HSM
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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