SCAN928028
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SCAN928028 8 Channel 10:1 Serializer with IEEE 1149.1 and At-Speed BIST
Check for Samples: SCAN928028
FEATURES
DESCRIPTION
•
The SCAN928028 integrates eight serializer devices
into a single chip. The SCAN928028 can
simultaneously serialize up to eight 10-bit data
streams. The 10-bit parallel inputs are LVTTL signal
levels. The serialized outputs are LVDS signals with
extra drive current for point-to-point and lightly loaded
multidrop applications. Each serializer block in the
SCAN928028 operates independently by using
strobes from a single shared PLL.
1
2
•
•
•
•
•
•
•
•
•
•
•
IEEE 1149.1 (JTAG) Compliant and At-Speed
BIST Test Mode.
All 8 Channels Synchronous to One Parallel
Clock Rate, from 18 to 66 MHz
Duplicates Function of Multiple DS92LV1021
and '1023 10-Bit Serializer Devices
Serializes from One to Eight 10-Bit Parallel
Inputs into Data Streams with Embedded
Clock
Eight 5 mA Modified Bus LVDS Outputs that
are Capable to Drive Double Terminations
@Speed Test - PRBS Generation to Check
LVDS Transmission Path to SCAN921224,
SCAN921226, SCAN921260, or SCAN926260
On Chip Filtering for PLL
740mW Typ Power Dissipation (Loaded, PRBS,
66MHz, 3.3V)
High Impedance Inputs and Outputs on Power
off
Single Power Supply at +3.3V (+/-10%)
196-pin NFBGA Package
Industrial Temperature Range Operation: -40
to +85°C
The SCAN928028 uses a single +3.3V power supply
with a typical power dissipation of 740mW (3.3V /
PRBS / 66 MHz). Each serializer channel has a
unique power down control to further conserve power
consumption.
For high-speed LVDS serial data transmission, line
quality is essential, thus the SCAN928028 includes
an @SPEED TEST function. Each Serializer channel
has the ability to internally generate a PRBS data
pattern. This pattern is received by specific
deserializers (SCAN921224) which have the
complement
PRBS
verification
circuit.
The
deserializer checks the data pattern for bit errors and
reports any errors on the test verification pins on the
deserializer.
For additional information - please see the Application
Information section in this datasheet.
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 © 2003–2013, Texas Instruments Incorporated
SCAN928028
SNLS163F – AUGUST 2003 – REVISED APRIL 2013
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Block Diagram
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) (2)
−0.3V to +4V
Supply Voltage (VCC)
−0.3V to (VCC +0.3V)
LVCMOS/LVTTL Input Voltage
−0.3V to +3.9V
Bus LVDS Driver Output Voltage
Bus LVDS Output Short Circuit Duration
Package Thermal Resistance
10ms
θJA 196 NFBGA:
34°C/W
θJC 196 NFBGA:
8°C/W
−65°C to +150°C
Storage Temperature
Junction Temperature
Lead Temperature
+125°C
(Soldering, 4 seconds)
+225°C
ESD Rating (HBM)
±1.5kV
Reliability Information
(1)
(2)
Transistor Count:
44.8k
Absolute Maximum Ratings are those values beyond which the safety of the device cannot be specified. 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.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
Recommended Operating Conditions
Supply Voltage (VCC)
Operating Free Air
Temperature (TA)
Clock Rate
2
Min
Typ
Max
3.0
3.3
3.6
V
−40
+25
+85
°C
66
MHz
18
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Electrical Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified. (1) (2)
Symbol
Parameter
Conditions
Pin/Freq.
Min
DINn[0-9], TCLK,
PWDNn, SYNCn, DEN,
BIST_ACT, TCK, TDI,
TMS, TRST,
BIST_SEL
Typ
Max
Units
2.0
VCC
V
MS_PWDN
2.2
VCC
V
DINn[0-9], TCLK,
PWDNn, MS_PWDN,
SYNCn, DEN,
BIST_ACT, TCK, TDI,
TMS, TRST,
BIST_SEL
GND
0.8
V
−0.87
−1.5
V
+/− 1
+10
μA
+10
μA
LVCMOS/LVTTL DC Specifications
VIH
High Level Input Voltage
VIL
Low Level Input Voltage
VCL
Input Clamp Voltage
IIN
ICL = −18 mA
Input Current
VIN = 0V or 3.6V
VOH
High level Output Voltage
IOH = -12mA
VOL
Low level Output Voltage
IOL = 12mA
IOS
Output Short Circuit Current
VOUT = 0V
IOZ
Tri-state Output Current
VOUT = 0V or 3.6V
DINn[0-9], TCLK,
PWDNn, MS_PWDN,
SYNCn, TCK, DEN,
BIST_ACT
−10
TDI, TMS, TRST,
BIST_SEL (3)
−20
2.4
TDO
V
-95
−10
0.5
V
-125
mA
+10
uA
Bus LVDS DC Specifications
Over recommended operating supply and temperature unless otherwise specified.
VOD
Output Differential Voltage (DO+)
- (DO-)
ΔVOD
Output Differential Voltage
Unbalance
350
RL = 100Ω, CL = 10pF
to GND
1.0
500
mV
3
35
mV
1.1
1.3
V
2
35
mV
−50
-90
mA
VOS
Offset Voltage
ΔVOS
Offset Voltage Unbalance
IOS
Output Short Circuit Current
DO = 0V, Din = H,
MS_PWDN and DEN =
2.4V
IOZ
Tri-state Output Current
MS_PWDN or DEN =
0.8V, DO = 0V OR
VDD
-10
+/-1
10
µA
IOX
Power-Off Output Current
VDD = 0V, DO = 0V or
3.6V
-10
+/− 1
10
µA
DOn+, DOn-
SER/DES SUPPLY CURRENT (apply to pins DVDD, PVDD and AVDD)
Over recommended operating supply and temperature ranges unless otherwise specified.
Supply Current
(SYNC pattern)
VCC = 3.6V,
RL = 100 Ω
f = 18MHz
145
f = 66MHz
175
Worst Case Supply Current
(Checker-board pattern)
VCC = 3.6V,
RL = 100 Ω Figure 1
f = 18 MHz
148
166
mA
f = 66 MHz
263
350
mA
Supply Current Powered Down
MS_PWDN = 0.1V,
DEN = 0V
0.35
1.0
mA
Worst Cast Power Saving Per
Channel Disabled
MS_PWDN = 3V,
PWDNn = 0V
ICCD
ICCXD
(Master)
ICCXD
(Ind. Ch)
(1)
(2)
(3)
mA
mA
66 MHz
6
mA
18 MHz
3.6
mA
Typical values are given for VCC = 3.3V and TA = +25°C.
Current into device pins is defined as positive. Current out of device pins is defined as negative. Voltages are referenced to ground
except VOD, and ΔVOD which are differential voltages.
BIST_SEL have a weak internal pull-up. In a noisy operating environment, it is recommended that an external pull up be used to ensure
that BIST_SEL is in the high state.
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Serializer Timing Requirements for TCLK
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
tTCP
Transmit Clock Period
15.15
tTCIH
Transmit Clock High
Time
30
tTCIL
Transmit Clock Low
Time
30
tCLKT
TCLK Input Transition
Time
tJIT
TCLK Input Jitter
(1)
(2)
Conditions
See Figure 3
Pin/Freq.
TCLK
Min
(1) (2)
Typ
Max
Units
55.5
ns
50
70
%
50
70
%
3
6
ns
80
psrms
Typical values are given for VCC = 3.3V and TA = +25°C.
Current into device pins is defined as positive. Current out of device pins is defined as negative. Voltages are referenced to ground
except VOD, and ΔVOD which are differential voltages.
Serializer Switching Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified. (1) (2)
Symbol
Parameter
tLLHT
Bus LVDS Low-to-High
Transition Time
(1)
(2)
(3)
4
tLHLT
Bus LVDS High-to-Low
Transition Time
tDIS
DIN (0-9) Setup to
TCLK
tDIH
DIN (0-9) Hold from
TCLK
tHZD
DO ± HIGH to
Tri-state Delay
tLZD
DO ± LOW to Tri-state
Delay
Conditions
Pin/Freq.
RL = 100Ω
CL=10pF to GND (3)
Figure 2
DOn+, DOn-
RL = 100Ω,
CL=10pF to GND
Figure 4
DINn(0-9), TCLK
RL = 100Ω,
CL=10pF to GND
Figure 5
tZHD
DO ± Tri-state to HIGH
Delay
tZLD
DO ± Tri-state to LOW
Delay
tSPD
SYNC Pattern Delay,
Figure 9
tPLD
Serializer PLL Lock
Time, Figure 6
tSD
Serializer Delay
tICR
Individual Channel
Power up Time
tMCR
Master Power up Time
tSTE
@Speed Test Enable
Time
RL = 100Ω
tSTD
@Speed Test Disable
Time
RL = 100Ω
tSKEW
Channel to Channel
Skew
RL = 100Ω,
CL=10pF to GND
Min
Typ
Max
Units
190
330
400
ps
190
330
400
ps
2.0
ns
1.5
ns
5.7
12
ns
6.9
12
ns
6.2
12
ns
5.8
12
ns
DOn+, DOn-, DEN
RL = 100Ω
CL=10pF to GND
TCLK, SYNCn,
DOn+, DOn-,
MS_PWDN
4*tTCP
5*tTCP
ns
510*tTCP
513*tTCP
ns
RL = 100Ω
CL=10pF to GND
Figure 8
DINn(0-9), TCLK,
DOn+, DOn-
tTCP + 1.0
tTCP + 3.5
tTCP + 5
ns
TCLK, DOn+, DOn-,
PWDNn Figure 7
60*tTCP
63*tTCP
70*tTCP
ns
TCLK, DOn+, DOn-,
MS_PWDN Figure 6
510*tTCP
513*tTCP
ns
RL = 100Ω,
CL=10pF to GND
BIST_ACT,
BIST_SEL (0:3),
TCLK, DOn+, DOn-
10*tTCP
ns
7*tTCP
ns
18 MHz
130
ps
66 MHz
80
ps
Typical values are given for VCC = 3.3V and TA = +25°C.
Current into device pins is defined as positive. Current out of device pins is defined as negative. Voltages are referenced to ground
except VOD, and ΔVOD which are differential voltages.
tLLHT, tLHLT, tDJIT and tRJIT specifications are Ensured by Design using statistical analysis.
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Serializer Switching Characteristics (continued)
Over recommended operating supply and temperature ranges unless otherwise specified.(1)(2)
Symbol
Parameter
Conditions
Pin/Freq.
tRJIT
Random Jitter
RL = 100Ω,
CL=10pF to
GND (3) (4)
Deterministic Jitter,
Figure 10
RL = 100Ω,
CL=10pF to
GND (3) (5)
18MHz
tDJIT
66MHz
(4)
(5)
Min
Typ
Max
Units
18MHz
39
45
ps (rms)
66MHz
18
21
ps (rms)
−225
20
257
ps (p-p)
−150
−55
68
ps (p-p)
tRJIT specification is the rms jitter measurement of the serializer output when the device is transmitting SYNC pattern.
tDJIT specification is measured with the serializer output transmitting checkerboard patterns. It is a measurement of the center
distribution of 0V (differential) crossing in comparsion with the ideal bit position. See Figure 10.
SCAN Circuitry Timing Requirements
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
Conditions
Min
fMAX
Maximum TCK Clock
Frequency
RL = 500Ω,
CL = 35 pF
18
Typ
Max
Units
MHz
tS
TDI to TCK, H or L
2.0
ns
tH
TDI to TCK, H or L
1.0
ns
tS
TMS to TCK, H or L
2.0
ns
tH
TMS to TCK, H or L
1.0
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
2.5
ns
AC Timing Diagrams and Test Circuits
Figure 1. ’Worst Case Icc Test Pattern
Figure 2. Serializer Bus LVDS Output Load and Transition Times
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Figure 3. Serializer Input Clock Transition Time
Figure 4. Serializer Setup/Hold Times
Figure 5. Serializer Input Clock Transition Time Tri-state Test Circuit and Timing
6
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Figure 6. Serializer PLL lock Time and MS_PWDN Tri-state Delays
TCLK
PWDNn
2.0V
0.8V
tICR
tZHD or tZLD
tHZDor tLZD
DOn+/TRI-STATE
TRI-STATE
Output Active
Figure 7. Individual Channel Power up Time, tICR
Figure 8. Serializer Delay
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Figure 9. SYNC Timing Delays
Figure 10. Deterministic Jitter and Ideal Bit Position
8
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Functional Description
The SCAN928028 combines eight 10:1 serializers into a single chip. Each of the eight serializers accepts 10 or
less data bits. The serializers then multiplex the data into a serial stream with embedded clock bits and route to
the LVDS output. The LVDS output is a 5 mA current loop driver. It provides enough drive for point-to-point and
lightly loaded multidrop applications. The serialized data stream is compatible with the DS92LV1210,
DS92LV1212A, DS92LV1224, DS92LV1260, SCAN921224, SCAN921226, SCAN921260, and SCAN926260 10bit deserializers from Texas Instruments.
Each of the eight channels on the SCAN928028 has their own serializer function but share a single PLL. There is
a single Transmit Clock (TCLK) for all eight channels. The data on all eight 10-bit interfaces is latched into the
device with the rising edge of TCLK. Each of the serialized data streams is independent of the others and
includes the embedded clock information. The skew between the serializer outputs is minimal.
There is a master power-down signal (MS_PWDN) to put the entire device into a low power consumption state.
In addition, there is a power-down control signal for each of the eight channels. This allows the device to
efficiently operate as one to eight 10-bit serializers.
The @SPEED TEST signal initiates the sending of a random data pattern over the LVDS links. This allows for
testing the links for bit error rates at the frequency they will be carrying data. In addition, JTAG can be used to
verify the device interconnects and initiate/verify the at-speed BIST.
The SCAN928028 has four operating modes. They are the Initialization, Data Transfer, Resynchronization,
@SPEED TEST states. There are also two passive states: Power-down and Tri-state. In addition to the active
and passive states, there are test modes for JTAG access and at-speed BIST.
The following sections describe each operating mode, passive state, and the test modes.
INITIALIZATION
Before the '8028 serializes and transmits data, it and the receiving deserializer device(s) must initialize the link.
Initialization refers to synchronizing the Serializer's and the Deserializer's PLLs to local clocks. The local clocks
should be the same frequency, or within the specified range if from different sources. After all devices
synchronize to local clocks, the Deserializers synchronize to the Serializers as the second and final initialization
step.
Step 1: After applying power to the serializer, the outputs are held in tri-state and the on-chip power-sequencing
circuitry disables the internal circuits. When Vcc reaches VccOK (2.1V), the PLL in the serializer begins locking
to the local clock (TCLK). A local on-board data source or other source provides the specified clock input to the
TCLK pin.
After locking to TCLK, the serializer is now ready to send data or SYNC patterns, depending on the level of the
SYNC input or a data stream at the data inputs. The SYNC pattern sent by the serializer consists of six ones and
six zeros switching at the input clock rate.
Step 2: The Deserializer PLL must synchronize to the Serializer to complete the initialization. (Refer to the
deserializer data sheet for operation details during this step of the Initialization State.) The Deserializer identifies
the rising clock edge in a synchronization pattern or non-repetitive data pattern. Depending on the data pattern
that it is being transmitted, the Deserializer will synchronize to the data stream from the Serializer after some
delay. At the point where the Deserializer's PLL locks to the embedded clock, the LOCK pin goes low and valid
data appears on the output.
The user's application determines control of the SYNC signal input. One recommendation is a direct feedback
loop from the LOCK pin on the deserializer. The serializer stops sending SYNC patterns when the SYNC input
returns to a low state.
DATA TRANSFER
After initialization, the serializer accepts data from the inputs DINn0 to DINn9. The serializer uses the rising edge
of the TCLK input to latch incoming data. If the SYNCn input is high for 4 TCLK cycles, the data on DINn0-DINn9
is ignored and SYNC pulses are transferred.
The serial data stream includes a start bit and stop bit appended by the serializer, which frame the ten data bits.
The start bit is always high and the stop bit is always low. The start and stop bits also function as clock bits
embedded in the serial stream.
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The Serializer transmits the data and clock bits (10+2 bits) at 12 times the TCLK frequency. For example, if
TCLK is 40 MHz, the serial rate is 40 X 12 = 480 Mbps. 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 18 MHz to 66 MHz nominal.
The serializer outputs (DO0± – DO7±) can drive a point-to-point connection or lightly loaded multidrop
connections. The outputs transmit data when the driver enable pin (DEN) is high, MS_PWDN and PWDNn are
high, and SYNCn is low. When DEN is driven low, all the serializer output pins will enter tri-state.
When any one of eight attached Deserializer channels synchronizes to the input from the Serializer, it drives its
LOCK pin low and synchronously delivers valid data on the output. The Deserializer locks to the embedded
clock, uses it to generate multiple internal data strobes, and drives the embedded clock on the RCLK pin. The
RCLK is synchronous to the data on the ROUT pins. While LOCK is low, data on ROUT is valid. Otherwise,
ROUT is invalid.
RESYNCHRONIZATION
Whenever one of the connected DS92LV1212, '1212A, '1224, '1226, '1260, or '6260 deserializers loses lock, it
will automatically try to resynchronize to the data stream from the serializer. If the data stream is not a repetitive
pattern, then the deserializer will automatically lock.
For example, if the deserializer's received embedded clock edge is not detected two times in succession, the
PLL loses lock and the LOCK pin is driven high. The '1212, '1212A, '1224, '1226, '1260, or '6260 deserializers
will automatically begin searching for the embedded clock edge. If it is a random data pattern, the deserializer
will lock to that stream. If the data pattern is repetitive, the deserializer’s PLL will not lock in order to prevent the
deserializer from locking to the data pattern rather than the clock. We refer to such patterns as repetitivemultiple-transition, RMT.
Therefore, if the data stream is not random data or the deserializer is the DS92LV1210, there needs to be a
feedback path from the deserializer to the serializer. This feedback path can be as simple as connecting the
deserializer's LOCK pin to the serializer's SYNC pin. This will automatically signal the serializers to send SYNC
patterns whenever the deserializer loses lock.
The user has the choice of allowing the deserializer to resynchronize to the data stream, or to force
synchronization by pulsing the Serializer SYNC pin. This scheme is left up to the user discretion.
POWER-DOWN
The Power-down state is a low power sleep mode that the Serializer and Deserializer typically occupy while
waiting for initialization, or to reduce power when there are no pending data transfers. The SCAN928028
serializers enter Power-down when MS_PWDN is driven low. In Power-down, the PLL stops and the outputs go
into tri-state. To exit Power-down, the system drives MS_PWDN high.
Each of the serializers in the '8028 also has an individual power down, PWDNn control pin. This control enables
the deactivation of individual serializers while allowing others to operate normally. The benefit is that spare
serializers can be allocated for backup operation, but not consuming power until employed for data transfers.
The Individual Power Down will NOT cause the PLL of the device to lose lock, but it will cause the specific
serializer channel to go into a low power sleep mode and its output go into tri-state. Thus, the device will NOT go
through the Initialization state when individual channels exit the Individual Power Down state, and the output of
the specific channel will become available after a short delay, see Figure 7 and spec tICR
TRI-STATE
When the system drives DEN pin low, the serializer outputs enter tri-state. This will tri-state the output pins
(DO0± to DO7±). When the system drives DEN high, the serializers will return to the previous state as long as all
other control pins remain static (PWDNn, TCLK, SYNCn, and DINn[0:9]).
10
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TEST FEATURES
Since the high-speed LVDS serial data transmission line quality is essential to the chipset operation, a means of
checking this signal integrity is built into the SCAN928028 serializer. Each Serializer channel has the ability to
transfer an internally generated PRBS data pattern. This pattern traverses the transmission line to the
deserializer. Specific deserializers (SCAN921224 for example) have the complement PRBS pattern verification
circuit. The deserializer checks the data pattern for bit errors and reports any errors on the test verification pins
on the deserializer.
The @SPEED feature uses 5 signal pins. The BIST_SEL[0:3] and BIST_ACT pins together determine the
functions of the BIST mode. The BIST_ACT signal activates the test feature. The BIST_SEL[0:3] selects 1 of 8
channels as the output for the BIST pattern. All channels perform BIST when BIST_ACT = H and
BIST_SEL=08H.
JTAG TEST FEATURES
In addition to using IEEE 1149.1 test access to the digital TTL pins, the SCAN928028 has two instructions to test
the LVDS interconnects. The first instruction 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 "atsystem-speed" interconnect test. It is executed in approximately 33mS with a maximum system clock speed of
66MHz. 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 (Run-Test-Idle) state within 4K system clocks (At a
TCLK 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.
If the user is unable to meet the constraint of moving both taps into RTI within 4K system clocks, the receiver
must be moved into the RTI state first. The receiver can then stay in RTI indefinitely until the transmitter is
moved into RTI and the BIST pattern begins. This is true for either SCAN initiated BIST or pin initiated
BIST_ALONE or any combination of the two.
Truth Table (BIST mode)
No BIST function performed when BIST_SEL (0:3) are set from 9H to FH even when BIST_ACT is set at HIGH. See (1) (2)
(1)
(2)
BIST_ACT
BIST_SEL
BIST_SEL
BIST_SEL
BIST_SEL
MODE
H
L
L
L
L
BIST on channel 0
H
L
L
L
H
BIST on channel 1
H
L
L
H
L
BIST on channel 2
H
L
L
H
H
BIST on channel 3
H
L
H
L
L
BIST on channel 4
H
L
H
L
H
BIST on channel 5
H
L
H
H
L
BIST on channel 6
H
L
H
H
H
BIST on channel 7
H
H
L
L
L
BIST on ALL
CHANNELS
L
X
X
X
X
NO BIST
L
H
H
H
H
Default - NO BIST
BIST_SEL have a weak internal pull-up. In a noisy operating environment, it is recommended that an external pull up be used to ensure
that BIST_SEL is in the high state.
No BIST function performed when BIST_SEL (0:3) are set from 9H to FH even when BIST_ACT is set at HIGH.
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Functional Block Diagram
Figure 11. SCAN928028 Functional Block Diagram
12
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APPLICATION INFORMATION
USING THE SCAN928028
The SCAN928028 is an easy to use serializer that combines eight 10:1 serializers into a single chip with a
maximum payload of 5.28Gbps. Each of the eight serializers accepts 10 or less data bits. The serializers then
multiplex the data into a serial data stream with embedded clock bits and route to the LVDS output at up to
660Mbps per channels. The LVDS output is a 5 ma current loop driver that can be used for point-to-point and
lightly loaded multidrop applications. Each of the eight channels has their own serializer function but share a
single Transmit Clock (TCLK) with a single PLL for the entire chip. The data on all eight channels is latched into
the device with the rising edge of TCLK and the data stream is compatible with the DS92LV1210,
DS92LV1212A, DS92LV1224, DS92LV1260, SCAN921224, SCAN921226, SCAN921260, and SCAN926260
deserializers from Texas Instruments.
If using less than 10 bits of data, it is recommended to tie off adjacent bits to the embedded clock bits to prevent
causing a RMT in the data payload. For example, if only using 8 bits, tie D0 High and D9 Low.
POWER CONSIDERATIONS
All CMOS design of the Serializer and Deserializer makes them inherently low power devices. Additionally, the
constant current source nature of the LVDS outputs minimize the slope of the speed vs. ICC curve of CMOS
designs.
PCB LAYOUT AND POWER SYSTEM CONSIDERATIONS
Circuit board layout and stack-up for the BLVDS devices should be designed to provide low-noise power feed to
the device. Good layout practice will also separate high-frequency or high-level inputs and outputs to minimize
unwanted stray noise pickup, feedback and interference. Power system performance may be greatly improved by
using thin dielectrics (2 to 4 mils) for power / ground sandwiches. This arrangement provides plane capacitance
for the PCB power system with low-inductance parasitic, especially proven effective at high frequencies above
approximately 50MHz, and makes the value and placement of external bypass capacitors less critical. External
bypass capacitors should include both RF ceramic and tantalum electrolytic types. RF capacitors may use values
in the range of 0.01 uF to 0.1 uF. Tantalum capacitors may be in the 2.2 uF to 10 uF range. Voltage rating of the
tantalum capacitors should be at least 5X the power supply voltage being used.
It is a recommended practice to use two vias at each power pin as well as at all RF bypass capacitor terminals.
Dual vias reduce the interconnect inductance by up to half, thereby reducing interconnect inductance and
extending the effective frequency range of the bypass components. Locate RF capacitors as close as possible to
the supply pins, and use wide low impedance traces (not 50 Ohm traces). Surface mount capacitors are
recommended due to their smaller parasitics. When using multiple capacitors per supply pin, locate the smaller
value closer to the pin. A large bulk capacitor is recommend at the point of power entry. This is typically in the
50uF to 100uF range and will smooth low frequency switching noise. It is recommended to connect power and
ground pins straight to the power and ground plane, with the bypass capacitors connected to the plane with via
on both ends of the capacitor. Connecting a power or ground pin to an external bypass capacitor will increase
the inductance of the path.
A small body size X7R chip capacitor, such as 0603, is recommended for external bypass. Its small body size
reduces the parasitic inductance of the capacitor. User must pay attention to the resonance frequency of these
external bypass capacitors, usually in the range of 20-30MHz range. To provide effective bypassing, very often,
multiple capacitors are used to achieve low impedance between the supply rails over the frequency of interest. At
high frequency, it is also a common practice to use two via from power and ground pins to the planes, reducing
the impedance at high frequency.
Some devices provide separate power and ground pins for different portions of the circuit. This is done to isolate
switching noise effects between different sections of the circuit. Separate planes on the PCB are typically not
required. Pin Description tables typically provide guidance on which circuit blocks are connected to which power
pin pairs. In some cases, an external filter many be used to provide clean power to sensitive circuits such as
PLLs.
Use at least a four layer board with a power and ground plane. Locate CMOS (TTL) swings away from the LVDS
lines to prevent coupling from the CMOS lines to the LVDS lines. Closely-coupled differential lines of 100 Ohms
are typically recommended for LVDS interconnect. The closely-coupled lines help to ensure that coupled noise
will appear as common-mode and thus is rejected by the receivers. Also the tight coupled lines will radiate less.
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TRANSMISSION MEDIA
The SCAN928028 Serializers can be used in point-to-point configuration of a backplane across PCB traces or
through cable interconnect. In point-to-point configurations the transmission media needs only to be terminated at
the receiver end. The SCAN928028 may also be used with double terminations for a total load or 50 Ohms for
use in certain limited multidrop applications. Termination impedances lower than 50 Ohms is not recommended.
TERMINATION
Termination of the LVDS interconnect is required. For point-to-point applications termination should be located at
the load end. Nominal value is 100 Ohms to match the line's differential impedance. Place the resistor as close
to the receiver inputs as possible to minimize the resulting stub between the termination resistor and receiver.
Additional general guidance can be found in the LVDS Owner's Manual - available in PDF format from the TI
web site at: http://www.ti.com/ww/en/analog/interface/lvds.shtml
SCAN928028 BLVDS SERIALIZER BYPASS RECOMMENDATIONS
General device specific guidance is given below. Exact guidance can not be given as it is dictated by other board
level /system level criteria. This includes the density of the board, power rails, power supply, and other integrated
circuit power supply needs.
For a typical application circuit, please see Figure 12.
DVDD = DIGITAL SECTION POWER SUPPLY
These pins supply the digital portion of the device. A 0.1uF capacitor is sufficient for these pins.
PVDD = PLL SECTION POWER SUPPLY
The PVDD pin supplies the PLL circuit. The PLL(s) require clean power for the minimization of Jitter. A supply
noise frequency in the 300kHZ to 1MHz range can cause increased output jitter. Certain power supplies may
have switching frequencies or high harmonic content in this range. If this is the case, filtering of this noise
spectrum may be required. A notch filter response is best to provide a stable VDD, suppression of the noise
band, and good high-frequency response (clock fundamental). This may be accomplished with a pie filter (CRC
or CLC). The pie filter should be located close to the PVDD power pin. Separate power planes for the PVDD pins
is typically not required.
AVDD = LVDS SECTION POWER SUPPLY
The AVDD pin supplies the LVDS portion of the circuit. The SCAN928028 has nine AVDD pins. Due to the
nature of the design, current draw is not excessive on these pins. A 0.1uF capacitor is sufficient for these pins. If
space is available a 0.01uF may be used in parallel with the 0.1uF capacitor for additional high frequency
filtering.
GROUNDS
The AGND pin should be connected to the signal common in the cable for the return path of any common-mode
current. Most of the LVDS current will be odd-mode and return within the interconnect pair. A small amount of
current may be even-mode due to coupled noise, and driver imbalances. This current should return via a low
impedance known path.
A solid ground plane is recommended for DVDD, PVDD or AVDD. Using a split plane may have a potential
problem of ground loops, or difference in ground potential at various ground pins of the device.
14
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Application Diagram
Figure 12. Typical Application Circuit
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Pin Diagram
Figure 13. Top View of SCAN928028 (196-pin NFBGA)
16
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Pin Descriptions
Pin Number
Name
Type
C7, C9, C10, D6, D7, D9, E5, E7,
G7
AGND
Analog ground.
C6, C8, C11, D5, D8, D10, E6,
E8, F7
AVDD
Analog power supply.
B12
BIST_ACT
3.3 V
CMOS
I
BIST Active. Control pin for BIST mode enable.When BIST_ACT = H
and BIST_SEL (0:3) = 0H to 8H, device will go to BIST mode
accordingly. See Truth Table (BIST mode) Default at Low
A13, B13, D11, E11
BIST_SEL
(0:3)
3.3 V
CMOS
I
BIST select. Control pins for which serializer is set for BIST mode.
See Truth Table (BIST mode) (1)
DEN
3.3 V
CMOS
I
Serializer output data enable. Enable data output DOUTn (0:9). n =
serializer number. When driven low, puts the Bus LVDS outputs in tristate. Default at Low.
M14
A2, A3, A12, B2, B3, C2, C4,
D12, E1, E2, E9, E10, E12, E13,
E14, F6, F10, H10, K6, K10,
M13, P1
DGND
E3, E4, F1, F2, F3, F4, F11, F12,
G1, G2, G3, G4, G11, G12, G14,
H1, H2, H3, H4, H11, H12, H13,
H14, J1, J2, J3, J4, J11, J12,
J13, J14, K1, K2, K3, K4, K11,
K12, K13, K14, L3, L4, L5, L6,
L7, L8, L9, L10, L11, L12, L13,
L14, M3, M4, M5, M6, M7, M8,
M9, M10, M11, N3, N4, N5, N6,
N7, N8, N9, N10, N11, P2, P3,
P4, P5, P6, P7, P8, P9, P10 P11,
P12
DINnx
3.3 V
CMOS
I
B11-A11, B10-A10, B9-A9, B8A8, B7-A7, A6-B6, A5-B5, A4-B4
Doutn±
Bus LVDS
O
A1, B1, C3, C5, D4, D13, D14,
F5, F8, F9, F13, G6, G10, G13,
H7,
DVDD
N14
G5, G8, G9, H5, H6, H8, H9, J5,
J6, J7, J9, J10
MS_PWDN
Digital Ground.
Data input. Inputs for the ten bit serializers. n = serializer number, x =
bit number. Default at Low.
Bus LVDS differential outputs. n = serializer number.
Digital power supply.
3.3 V
CMOS
I
Master Powerdown. MS_PWDN driven low shuts down the PLL and
tri-state all outputs, putting the device into a low power ’sleep’ mode.
Default at Low.
NC (1:12)
No connect.
C1, D1
PGND
PLL ground.
D2, D3
PVDD
PLL power supply.
N1, N2, N13, M1, M2, M12, P13,
P14
J8, K5, K7, K8, K9, L1, L2, N12
(1)
Description
PWDN (0:7)
3.3 V
CMOS
I
Individual Powerdown. PWDN (0:7) driven low puts individual
serializers into tri-state, low power ’sleep’ mode. Default at Low.
SYNC (0:7)
3.3 V
CMOS
I
SYNC pattern enable. When driven high for a mininum of 4 cycles,
SYNC patterns will be transmitted on the Bus LVDS serial output. The
SYNC pattern sent by the serializer consists of six ones and six zeros
switching at the input clock rate. SYNC pattern continues to be sent if
SYNC continues at high. Default at Low. See Functional Description.
C13
TCK
Test Clock Input to support IEEE 1149.1
B14
TDI
Test Data Input to support IEEE 1149.1. There is an internal pullup
resistor that defaults this input to high per IEEE 1149.1.
C14
TDO
Test Data Output to support IEEE 1149.1
A14
TMS
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.
C12
TRSTN
Test Reset Input to support IEEE 1149.1. There is an internal pullup
resistor that defaults this input to high per IEEE 1149.1.
BIST_SEL have a weak internal pull-up. In a noisy operating environment, it is recommended that an external pull up be used to ensure
that BIST_SEL is in the high state.
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Pin Descriptions (continued)
Pin Number
F14
18
Name
Type
TCLK
3.3 V
CMOS
I
Description
Transmit Clock. Input for 18 MHz - 66 MHz (nominal) system clock.
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REVISION HISTORY
Changes from Revision E (April 2013) to Revision F
•
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 18
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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)
SCAN928028TUF/NOPB
ACTIVE
NFBGA
NZH
196
119
RoHS & Green
SNAGCU
Level-3-260C-168 HR
-40 to 85
SCAN928028T
UF
>B
(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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