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CLC020
SMPTE 259M Digital Video Serializer with Integrated
Cable Driver
General Description
The CLC020 SMPTE 259M Digital Video Serializer with Integrated Cable Driver is a monolithic integrated circuit that encodes, serializes and transmits bit-parallel digital data conforming to SMPTE 125M and SMPTE 267M component
video and SMPTE 244M composite video standards. The
CLC020 can also serialize other 8 or 10-bitparalleldata.The
CLC020 operates at data rates from below 100 Mbps to over
400 Mbps. The serial data clock frequency is internally generated and requires no external frequency setting components, trimming or filtering
*
. Functions performed by the
CLC020 include: parallel-to-serial data conversion, data encoding using the polynomial (X
9+X4
+1), data format conversion from NRZ to NRZI, parallel data clock frequency multiplication and encoding with the serial data, and coaxial cable
driving. Input for sync (TRS) detection disabling and a PLL
lock detect output are provided. The CLC020 has an exclusive built-in self-test (BIST) and video test pattern generator
(TPG) with 4 component video test patterns, reference
black, PLLandEQpathologicals and modified colour bars, in
4:3 and 16:9 raster and both NTSC and PALformats
*
. Separate power pins for the output driver, VCO and the digital
logic improve power supply rejection, output jitter and noise
performance.
The CLC020 is the ideal complement to the CLC011B
SMPTE 259M Serial Digital Video Decoder, CLC014 Active
Cable Equalizer, CLC016 Data Retiming PLL (clock-data
separator), CLC018 8X8 Digital Crosspoint Switch and
CLC006 or CLC007 Cable Drivers, for a complete
parallel-serial-parallel, high-speed data processing and
transmission system.
The CLC020 is powered from a single 5V supply. Power dissipation is typically 235 mW including two 75Ω
back-matched output loads. The device is packaged in a
JEDEC 28-lead PLCC.
Features
n SMPTE 259M serial digital video standard compliant
n No external serial data rate setting or VCO filtering
components required
*
n Built-in self-test (BIST) and video test pattern generator
(TPG) with 16 internal patterns
*
n Supports all NTSC and PAL standard component and
composite serial video data rates
n HCMOS/TTL-compatible data and control inputs and
outputs
n 75Ω ECL-compatible, differential, serial cable-driver
outputs
n Fast VCO lock time:
<
75 µs
n Single +5V TTL or −5V ECL supply operation
n Low power: 235 mW typical
n 28-lead PLCC package
n Commercial temperature range 0˚C to +70˚C
Applications
n SMPTE 259M parallel-to-serial digital video interfaces
for:
— Video cameras
— VTRs
— Telecines
— Video test pattern generators and digital video test
equipment
n Non-SMPTE video applications
n Other high data rate parallel/serial video and data
systems
*
Patents applications made or pending.
Typical Application
DS100917-12
February 2000
CLC020 SMPTE 259M Digital Video Serializer with Integrated Cable Driver
© 2000 National Semiconductor Corporation DS100917 www.national.com
Page 2
Block Diagram
Connection Diagram
DS100917-1
DS100917-2
28-Pin PLCC
Order Number CLC020ACQ
See NS Package Number V28A
CLC020
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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.
Supply Voltage (V
DD−VSS
) 6.0V
CMOS/TTL Input Voltage (V
I
) −0.5V to (VDD+ 0.5V)
CMOS/TTL Output Voltage (V
O
) −0.5V to (VDD+ 0.5V)
CMOS/TTL Input Current (single input)
V
I=VSS
−0.5V −5 mA
V
I=VDD
+0.5V +5 mA
Input Current, Other Inputs
±
1mA
CMOS/TTL Output Source/Sink Current
±
10 mA
SDO Output Source Current 20 mA
Package Thermal Resistance
θ
JA
28-lead PLCC 85˚C/W
θ
JC
28-lead PLCC 35˚C/W
Storage Temp. Range −65˚C to +150˚C
Junction Temperature +150˚C
Lead Temperature (Soldering 4 Sec) +260˚C
ESD Rating (HBM)
>
2.5 kV
ESD Rating (MM)
>
300 V
Transistor Count 33,400
Recommended Operating
Conditions
Supply Voltage (VDD−VSS) 5.0V±10%
CMOS/TTL Input Voltage V
SS
to V
DD
Maximum DC Bias on SDO pins 3.0V±10%
Operating Free Air Temperature (T
A
) 0˚C to +70˚C
DC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Notes 2, 3).
Symbol Parameter Conditions Reference Min Typ Max Units
V
IH
Input Voltage High Level D0 through D9,
P
CLK
, TPG_EN
and Sync.
Detect Enable
2.0 V
DD
V
V
IL
Input Voltage Low Level V
SS
0.8 V
I
IH
Input Current High Level VIH=V
DD
+40 +60 µA
I
IL
Input Current Low Level VIL=V
SS
-1 -20 µA
V
OH
CMOS Output Voltage
High Level
IOH= −10 mA Lock Detect,
Test Out
2.4 4.7 V
DD
V
V
OL
CMOS Output Voltage
Low Level
IOL= +10 mA 0.0 0.3 VSS+ 0.5V V
V
SDO
Serial Driver Output
Voltage
RL=75Ω1%,
R
REF
= 1.69 kΩ 1%,
Figure 2
SDO, SDO 700 800 900 mV
P-P
I
DD
Power Supply Current,
Total
RL=75Ω1%,
R
REF
= 1.69 kΩ 1%,
P
CLK
= 27 MHz,
Figure 2
,
NTSC Colour Bar Pattern
47 60 mA
AC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Note 3).
Symbol Parameter Conditions Reference Min Typ Max Units
BR
SDO
Serial data rate RL=75Ω, AC coupled, (Note 5) SDO, SDO 100 400 Mbps
t
j
Serial output jitter 270 Mbps,
Figure 2
, (Note 6) SDO, SDO 220 ps
P-P
t
jit
Serial output jitter (Notes 4, 5) SDO, SDO 100 200 ps
P-P
tr,t
f
Rise time, Fall time 20%–80%, (Notes 4, 5) SDO, SDO 500 800 1500 ps
Output overshoot SDO, SDO
1%
t
LOCK
Lock time 270 Mbps, (Notes 5, 7) 75 µs
t
SU
Setup time
Figure 3
DNto P
CLK
32 ns
t
HLD
Hold time
Figure 3
DNfrom P
CLK
1.5 1 ns
L
GEN
Output inductance (Note 4) SDO, SDO 6nH
R
GEN
Output resistance (Note 4) SDO, SDO 25k Ω
CLC020
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AC Electrical Characteristics (Continued)
Note 1: “Absolute Maximum Ratings” are those parameter values beyond which the life and operation of the device cannot be guaranteed. The stating herein of
these maximums shall not be construed to imply that the device can or should be operated at or beyond these values. The table of “Electrical Characteristics” specifies acceptable device operating conditions.
Note 2: Current flow into device pins is defined as positive. Current flow out of device pins is defined as negative. All voltages are stated referenced to V
SS
=0V.
Note 3: Typical values are stated for V
DD
= +5.0V and TA= +25˚C.
Note 4: Specification is guaranteed by design.
Note 5: R
L
=75Ω, AC-coupled@270 M
bps,RREF
= 1.69 kΩ 1%, See
Test Loads
and
Figure 2
.
Note 6: CLC020 mounted in the SD020EVK board, configured in BIST mode (NTSC color bars) with P
CLK
= 27MHz derived from Tektronix TG2000 black-burst ref-
erence. Timing jitter measured with Tektronix VM700T using jitter measurement FFT mode, frame rate, 1kHz filter bandwidth, Hanning window.
Note 7: Measured from rising-edge of first P
CLK
cycle until Lock Detect output goes high (true).
Test Loads
DS100917-3
All resistors in Ohms, 1% tolerance.
FIGURE 1. Test Loads
CLC020
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Test Loads (Continued)
Timing Diagram
Device Operation
The CLC020 SMPTE 259M Digital Video Serializer is used in
digital video signal origination and processing equipment:
cameras, video tape recorders, telecines, video test equipment and others. It converts parallel component or composite digital video signals into serial format. Logic levels within
this equipment are normally TTL-compatible as produced by
CMOS or bipolar logic devices. The encoder outputs
ECL-compatible serial digital video (SDV) signals conforming to SMPTE 259M-1997. The CLC020 operates at all standard SMPTE and ITU-R parallel data rates.
DS100917-4
FIGURE 2. Test Circuit
DS100917-5
FIGURE 3. Setup and Hold Timing
CLC020
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Device Operation (Continued)
VIDEO DATA PROCESSING CIRCUITS
The input data register accepts 8 or 10-bit parallel data and
clock signals having CMOS/TTL-compatible signal levels.
Parallel data may conform to any of several standards:
SMPTE 125M, SMPTE 267M, SMPTE 244M or ITU-R
BT.601. If data is 8-bit, it is converted to a 10-bit representation according to the type of data being input: component
4:2:2 per SMPTE 259M paragraph 7.1.1, composite NTSC
per paragraph 8.1.1 or composite PAL per paragraph 9.1.1.
Output from this register feeds the SMPTE polynomial
generator/serializer and sync detector. All CMOS inputs including the P
CLK
input have internal pull-down devices.
The sync detector or TRS character detector accepts data
from the input register. The detection function is controlled
by Sync Detect Enable, a low-true, TTL-compatible, external
signal. Synchronization words, the timing reference signals
(TRS), start-of-active-video (SAV) and end-of-active-video
(EAV) are defined in SMPTE 125M-1995 and 244M. The
sync detector supplies control signals to the SMPTE polynomial generator that identify the presence of valid video data.
The sync detector performs input TRS character
LSB-clipping as prescribed in ITU-R-BT.601. LSB-clipping
causes all TRS characters with a value between 000h and
003h to be forced to 000h and all TRS characters with a
value between 3FCh and 3FFh to be forced to 3FFh. Clipping is done prior to encoding.
The SMPTE polynomial generator accepts the parallel
video data and encodes it using the polynomial X
9+X4
+1 as
specified in SMPTE 259M–1997, paragraph 5 and Annex C.
The scrambled data is then serialized for output.
The NRZ-to-NRZI converter accepts serial NRZ data from
the SMPTE polynomial genertor and converts it to NRZI using the polynomialX+1perSMPTE 259M–1997, paragraph
5.2 and Annex C. The transmission bit order is LSB first, per
paragraph 6. The converter’s output feeds the output driver
amplifier.
PHASE-LOCKED LOOP AND VCO
The phase-locked loop (PLL) system generates the output
serial data clock at 10x the parallel data clock frequency.
This system consists of a VCO, divider chain,
phase-frequency detector and internal loop filter. The VCO
free-running frequency is internally set. The PLL automatically generates the appropriate frequency for the serial clock
rate using the parallel data clock (P
CLK
) frequency as its reference. Loop filtering is internal to the CLC020. The VCO
has separate V
SSO
and V
DDO
power supply feeds, pins 15
and 16, which may be supplied power independently via an
external low-pass filter, if desired. The PLL acquisition (lock)
time is less than 75 µs
@
270 Mbps.
LOCK DETECT
The Lock Detect output of the phase-frequency detector indicates the PLL lock condition. It is a logic HIGH when the
loop is locked. The output is CMOS/TTL-compatible and is
suitable for driving other CMOS devices or a LED indicator.
SERIAL DATA OUTPUT BUFFER
The current-mode serial data outputs provide low-skew
complimentary or differential signals. The output buffer design can drive 75Ω coaxial cables (AC-coupled) or 10k/100k
ECL/PECL-compatible devices (DC-coupled). Output levels
are 800 mV
P-P
±
10% into 75Ω AC-coupled, back-matched
loads. The output level is 400 mV
P-P
±
10% when
DC-coupled into 75Ω (See Application Information for details). The 75Ω resistors connected to the SDO outputs are
back-matching resistors. No series back-matching resistors
should be used. SDO output levels are controlled by the
value of R
REF
connected to pin 19. The value of R
REF
is nor-
mally 1.69 kΩ,
±
1%. The output buffer is static when the de-
vice is in an out-of-lock condition. Separate V
SSSD
and
V
DDSD
power feeds, pins 21 and 24, are provided for the se-
rial output driver.
POWER-ON RESET
The CLC020 has an internally controlled, automatic,
power-on reset circuit. This circuit clears TRS detection circuitry,all latches, registers, counters and polynomial generators and disables the serial output. The SDO outputs are
tri-stated during power-on reset. The part will remain in the
reset condition until the parallel input clock is applied.
BUILT-IN SELF-TEST (BIST)
The CLC020 has a built-in self-test (BIST) function. The
BIST performs a comprehensive go-no-go test of the device.
The test uses either a full-field color bar for NTSC or a PLL
pathological for PALas the test data pattern. Data is input internally to the input data register, processed through the device and tested for errors.
Table 1
gives device pin functions
and
Table 2
gives the test pattern codes used for this function. The signal level at Test_Output,pin 26, indicates a pass
or fail condition.
The BIST is initiated by applying the code for the desired
BIST to D0 throught D3 (D9 through D4 are 00h) and a
27 MHz clock at the P
CLK
input. Since all parallel data inputs
are equipped with an internal pull-down device, only those
inputs D0 through D3 which require a logic-1 need be pulled
high.After the Lock_Detect output goes high (true) indicating
the VCO is locked on frequency,TPG_Enable, pin 17, is then
taken to a logic high. TPG_Enable may be temporarily connected to the Lock_Detect output to automate BIST operation. Test_Output, pin 26, is monitored for a pass/fail indication. If no errors have been detected, this output will go to a
logic high level approximately 2 field intervals after
TPG_Enable is taken high. If errors have been detected in
the internal circuitry of the CLC020, Test_Output will remain
low until the test is terminated. The BIST is terminated by
taking TPG_Enable to a logic low. Continuous serial data
output is available during the test.
TEST PATTERN GENERATOR
The CLC020 features an on-board test pattern generator
(TPG). Four full-field component video test patterns for both
NTSC and PALstandards, and 4x3 and 16x9 raster sizes are
produced. The test patterns are: flat-field black, PLL pathological, equalizer (EQ) pathological and a modified 75%,
8-color vertical bar pattern. The pathologicals follow recommendations contained in SMPTE RP 178–1996 regarding
the test data used. The color bar pattern does not incorporate bandwidth limiting coding in the chroma and luma data
when transitioning between the bars. For this reason, it may
not be suitable for use as a visual test pattern or for input to
video D-to-A conversion devices unless measures are taken
to restrict the production of out-of-band frequency components.
The TPG is operated by applying the code for the desired
test pattern to D0 through D3 (D4 through D9 are 00h). Since
all parallel data inputs are equipped with an internal
pull-down device, only those inputs D0 through D3 which require a logic-1 need be pulled high. Next, apply a 27 or
CLC020
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Device Operation (Continued)
36 MHz signal, appropriate to the raster size desired, at the
P
CLK
input and wait until the Lock_Detect output goes true
indicating the VCO is locked on-frequency. Then, take
TPG_Enable, pin 17, to a logic high. The serial test pattern
data appears on the SDO outputs. TPG_Enable may be
temporarily connected to the Lock_Detect output to automate TPG operation. The TPG mode is exited by taking
TPG_Enable to a logic low.
Table 1
gives device pin func-
tions for this mode.
Table 2
gives the available test patterns
and selection codes.
TABLE 1. BIST and Test Pattern Generator Control Functions
Pin Name Function
3 D0 TPG code input LSB
4 D1 TPG code input
5 D2 TPG code input
6 D3 TPG code input MSB
17 TPG_EN TPG Enable, active high true
26 Test_Out BIST Pass/Fail output. Pass=High
(See text for timing requirements)
DS100917-6
FIGURE 4. Built-In Self-Test Control Sequence
DS100917-7
FIGURE 5. Test Pattern Generator Control Sequence
CLC020
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Device Operation (Continued)
TABLE 2. Component Video Test Pattern Selection
Standard Frame Test Pattern D3 D2 D1 D0
NTSC 4x3 Flat-field black 0000
NTSC 4x3 PLL pathological 0001
NTSC 4x3 EQ pathological 0010
NTSC 4x3 Color bars, 75%, 8-bars (modified, see text), BIST 0011
PAL 4x3 Flat-field black 0100
PAL 4x3 PLL pathological, BIST 0101
PAL 4x3 EQ pathological 0110
PAL 4x3 Color bars, 75%, 8-bars (modified, see text) 0111
NTSC 16x9 Flat-field black 1000
NTSC 16x9 PLL pathological 1001
NTSC 16x9 EQ pathological 1010
NTSC 16x9 Color bars, 75%, 8-bars (modified, see text) 1011
PAL 16x9 Flat-field black 1100
PAL 16x9 PLL pathological 1101
PAL 16x9 EQ pathological 1110
PAL 16x9 Color bars, 75%, 8-bars (modified, see text) 1111
Note: D9 through D4 = 0 (binary)
CLC020
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Pin Descriptions
Pin # Name Description
1V
DD
Positive power supply input (digital logic)
2V
DD
Positive power supply input (digital logic)
3 D0 Parallel data input/Test pattern select (LSB)
4 D1 Parallel data input/Test pattern select
5 D2 Parallel data input/Test pattern select
6 D3 Parallel data input/Test pattern select (MSB)
7 D4 Parallel data input
8 D5 Parallel data input
9 D6 Parallel data input
10 D7 Parallel data input
11 D8 Parallel data input
12 D9 Parallel data input
13 PCLK Parallel clock input
14 Lock Detect VCO Lock Detect output (high-true)
15 V
SSO
Negative power supply input (PLL supply)
16 V
DDO
Positive power supply input (PLL supply)
17 TPG_EN Test Pattern Generator (TPG) Enable input (high-true)
18 V
SSOD
Negative power supply input (PLL digital supply)
19 R
REF
Output driver level control
20 V
DDOD
Positive power supply input (PLL digital supply)
21 V
SSSD
Negative power supply input (Output driver)
22 SDO Serial data true output
23 SDO
Serial data complement output
24 V
DDSD
Positive power supply input (Output driver)
25 Sync Detect Enable
Parallel data sync detection enable input (low true)
26 Test_Out BIST Pass/Fail output
27 V
SS
Negative power supply input (digital logic)
28 V
SS
Negative power supply input (digital logic)
Note: All CMOS/TTL inputs have internal pull-down devices.
CLC020
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Application Information
A typical application circuit for the CLC020 is shown in
Fig-
ure 6
. This circuit demonstrates the capabilities of the
CLC020 and allows its evaluation in a variety of configurations. An assembled demonstration board with more comprehensive evaluation options is available, part number
SD020EVK. The board may be ordered through any of Na-
tional’s sales offices. Complete circuit board layouts and
schematics, for the SD020EVK are available on National’s
WEB site in the application information for this device. For
latest information, please see:
www.national.com/appinfo/interface
APPLICATION CIRCUIT
Several different input and output drive and loading options
can be constructed on the SD020EVK application circuit
board,
Figure 7
. Pin headers are provided for input cabling
and control signal access. The appropriate value resistor
packs, 220 and 330Ω for TTL or 50Ω for signal sources requiring such loading, should be installed at RP1-4 before applying input signals. Output loading can be adapted to both
50 and 75Ω test equipment. Resistors R3 and R4, 24.9Ω,
size 1206 surface-mount, should be installed when using
50Ω test loads. Output levels at J1 and J2 will be attenuated
by 3.5 dB under these conditions. (Note: it is necessary to
cut and remove the traces shorting the mounting pads of R3
and R4 before installing these components).
The board’s outputs may be DC interfaced to PECL inputs by
first installing 124Ω resistors at R1B and R2B, changing R1A
and R2A to 187Ω and replacing C1 and C2 with short circuits. The PECL inputs should be directly connected to J1
and J2 without cabling. If 75Ω cabling is used to connect the
CLC020 to the PECL inputs, the voltage dividers used on the
CLC020 outputs must be removed and re-installed on the
circuit board where the PECL device is mounted. This will
provide correct termination for the cable and biasing for both
the CLC020’s outputs and the PECL inputs. It is most important to note that a 75Ω or equivalent DC loading (measured
with respect to the negative supply rail) must always be installed at both of the CLC020’s SDO outputs to obtain proper
signal levels from device. When using 75Ω
Thevenin-equivalent load circuits, the DC bias applied to the
SDO outputs should not exceed +3V with respect to the
negative supply rail. Serial output levels should be reduced
to 400 mV
p-p
by changing R
REF
to 3.4 kΩ.
The Test Out output circuit includes a series 453Ω resistor,
R10, which permits driving 50Ω test loads. The signal level
at J3 will be attenuated by 20 dB. For high impedance test
loads (
>
500Ω), replace R10 with a short circuit. If the Lock
Detect output is to be externally monitored, the attached
monitoring circuit should present a DC resistance greater
than 5 kΩ so as not to affect Lock Detect indicator operation.
DS100917-8
FIGURE 6. Typical Application Circuit
CLC020
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Application Information (Continued)
MEASURING JITTER
The test method used to obtain the timing jitter value given in
the AC Electrical Specification table is based on procedures
and equipment described in SMPTE RP 192-1996. The recommended practice discusses several methods and indicator devices. An FFT method performed by standard video
test equipment was used to obtain the data given in this data
sheet. As such, the jitter characteristics (or jitter floor) of the
measurement equipment, particularly the measurement analyzer, become integral to the resulting jitter value. The
method and equipment were chosen so that the test can be
easily duplicated by the design engineer using most standard digital video test equipment. In so doing, similar results
should be achieved. The intrinsic jitter floor of the CLC020’s
PLL is approximately 25% of the typical jitter given in the
electrical specifications. In production, device jitter is measured on automatic IC test equipment (ATE)using a different
method compatible with that equipment. Jitter measured using this ATE yields values approximately 50% of those obtained using the video test equipment.
The jitter test setup used to obtain values quoted in the data
sheet consists of:
•
National Semiconductor SD020EVK, CLC020 evaluation
kit
•
Tektronix TG2000 signal generation platform with DVG1
option
•
Tektronix VM700T Option 1S Video Measurement Set
•
Tektronix TDS 794D, Option C2 oscilloscope
•
Tektronix P6339A passive probe
•
75 Ohm coaxial cable, 3ft., Belden 8281 or RG59 (2 required)
•
ECL-to-TTL/CMOS level converter/amplifier,
Figure 9
Apply the black-burst reference clock from the TG2000 signal generator’s BG1 module 27MHz clock output to the level
converter input. The clock amplitude converter schematic is
shown in Figure 9. Adjust the input bias control to give a 50%
duty cycle output as measured on the oscilloscope/probe
system. Connect the level translator to the SD020EVK
board, connector P1, P
CLK
pins (the outer-most row of pins
is ground). Configure the SD020EVK to operate in the NTSC
colour bars, BIST mode. Configure the VM700T to make the
jitter measurement in the jitter FFT mode at the frame rate
DS100917-9
Connect LOCK DETECT to TPG ENABLE for test pattern generator function.
Remove RP1 & RP3 and replace RP2 & RP4 with 50Ω resistor packs for coax interfacing.
Install RP1-4 when using ribbon cable for input interfacing.
This board is designed for use with TTL power supplies only.
For optional ECL compatible load: R1A = R2A = 187; R1B = R2B = 124.
All resistances & impedances in Ohms. Values with 3 significant digits are 1%; with 2 digits 5%.
FIGURE 7. SD020EVK Schematic Diagram
CLC020
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Application Information (Continued)
with 1kHz filter bandwidth and Hanning window. Configure
the setup as shown in
Figure 8
. Switch the test equipment on
(from standby mode) and allow all equipment temperatures
stabilize per manufacturer’s recommendation. Measure the
jitter value after allowing the instrument’s reading to stabilize
(about 1 minute). Consult the VM700T Video Measurement
Set Option 1S Serial Digital Measurements User Manual
(document number 071-0074-00) for details of equipment
operation.
The VM700T measurement system’s jitter floor specification
at 270Mbps is given as 200ps
±
20% (100ps±5% typical) of
actual components from 50Hz to 1MHz and 200ps +60%,
-30% of actual components from 1MHz to 10MHz. To obtain
the actual residual jitter of the CLC020, a root-sum-square
adjustment of the jitter reading must be made to compensate
for the measurement system’s jitter floor specification. For
example, if the jitter reading is 250ps, the CLC020 residual
jitter is the square root of (250
2
− 2002) = 150ps. The accu-
racy limits of the reading as given above apply.
DS100917-10
FIGURE 8. Jitter Test Circuit
DS100917-13
FIGURE 9. ECL-to-TTL/CMOS level converter/amplifer
CLC020
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Application Information (Continued)
PCB LAYOUT AND POWER SYSTEM BYPASS
RECOMMENDATIONS
Circuit board layout and stack-up for the CLC020 should be
designed to provide noise-free power to the device. Good
layout practice also will 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 (4 to 10 mils) for
power/ground sandwiches. This increases the intrinsic capacitance of the PCB power system which improves power
supply filtering, especially at high frequencies, 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 0.01 µF to 0.1 µF. Tantalum capacitors may be in the range 2.2 µF to 10 µF. Voltage rating for
tantalum capacitors should be at least 5x the power supply
voltage being used. It is recommended practice to use two
vias at each power pin of the CLC020 as well as 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.
The outer layers of the PCB may be flooded with additional
V
SS
(ground) plane. These planes will improve shielding and
isolation as well as increase the intrinsic capacitance of the
power supply plane system. Naturally, to be effective, these
planes must be tied to the V
SS
power supply plane at frequent intervals with vias. Frequent via placement also improves signal integrity on signal transmission lines by providing short paths for image currents which reduces signal
distortion. The planes should be pulled back from all transmission lines and component mounting pads a distance
equal to the width of the widest transmission line or the thickness of the dielectric separating the transmission line from
the internal power or ground plane(s) whichever is greater.
Doing so minimizes effects on transmission line impedances
and reduces unwanted parasitic capacitances at component
mounting pads.
In especially noisy power supply environments, such as is
often the case when using switching power supplies, separate filtering may be used at the CLC020’s VCO and output
driver power pins. The CLC020 was designed for this situation. The digital section, VCO and output driver power supply
feeds are independent (see pinout description table and pinout drawing for details). Supply filtering may take the form
of L-section or pi-section, L-C filters in series with these V
DD
inputs. Such filters are available in a single package from
several manufacturers. Despite being independent feeds, all
device power supplies should be applied simultaneously as
from a common source. The CLC020 is free from power supply latch-up caused by circuit-induced delays between the
device’s three separate power feed systems.
REPLACING THE GENNUM GS9022
The CLC020 is form-fit-function compatible with the Gennum
GS9022. The CLC020 can improve the performance of
GS9022 applications using the existing PCB layout with the
removal of certain components or changes to component
values. New layouts using the CLC020 will benefit from the
greatly reduced ancilliary component count and more compact layout.
The CLC020 does not require external VCO filtering components. The external VCO filtering components at pin 17 of
the GS9022 may remain connected to the CLC020 without
complications. It is suggested that these be removed from
DS100917-11
FIGURE 10. Jitter Plots
CLC020
www.national.com13
Page 14
Application Information (Continued)
the circuit board. The CLC020 uses pin 17 for its test pattern
generator enable function. You will find the TPG function
very useful when you make this change.
Remove the C
OSC
capacitor used by the GS9022 at pin 26.
The CLC020 uses pin 26 as the BIST pass/fail indicator output. You may attach a LED as an indicator to this pin, if desired. LED current should be limited to 10 mA maximum. The
same LED type and current limiting resistor shown in
Figure
7
at the Lock Detect output may be used for this indicator
function.
Remove any capacitor attached to pin 19. A capacitor at-
tached to pin 19 will cause distortion of the output V
OH
level.
The former data rate setting resistor, R
VCO
, at pin 19 now
functions as the output level setting resistor, R
REF
. It must be
changed to a 1.69 kΩ, 1% value for correct output level setting.
The input series resistors and the P
CLK
risetime filter capacitor used with the GS9022 are not needed for the CLC020.
These components should be removed from the circuit
board and the resistors replaced by short circuits (0Ω resistors). These series resistors will increase input signal rise
and fall times if left on the board.
The CLC020 has current-mode serial cable driver outputs.
These outputs have very high internal generator resistance
as one would expect of a current source. Though these
current-mode outputs can produce the equivalent drive volt-
ages into the load, it is necessary to change and simplify the
typical GS9022 output circuit normally recommended for that
device. The output load resistors at pins 22 and 23 must be
changed to 75Ω, 1% values. These resistors become the
back-matching loads across which the CLC020’s outputs develop drive voltage. The series back-matching resistors used
on the GS9022 should be removed and replaced with short
circuits. The risetime compensating capacitors across these
resistors should be removed.
Pin 28 on the CLC020 is V
SS
and must be connected to the
negative supply or ground. On layouts designed to mount
the GS9022, the series R-C network connected to this pin
should be replaced by short circuits (0Ω resistors).
The pull-up resistor connected to the Lock Detect output, pin
14, should be removed. It may be replaced by a LED and
current limiting resistor connected to V
SS
if a visual lock indi-
cator is desired.
The CLC020 has an internal pull-down at the Sync Detect
Enable input and may be left unconnected in SMPTE
video-only applications.
The CLC020 has independent power supply pins for the
VCO, V
SSO
, pin 15 and V
DDO
, pin 16. The CLC020 has an
output driver negative supply, V
SSSD
, at pin 21. The output
driver positive supply, V
DDSD
, is pin 24 (as on the GS9022).
On new layouts, additional power supply filtering may be
added at these pins, if desired.
CLC020
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Page 15
Physical Dimensions inches (millimeters) unless otherwise noted
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
National Semiconductor
Corporation
Americas
Tel: 1-800-272-9959
Fax: 1-800-737-7018
Email: support@nsc.com
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Europe
Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
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National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
Email: ap.support@nsc.com
National Semiconductor
Japan Ltd.
Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
www.national.com
28-Pin PLCC
Order Number CLC020ACQ
NS Package Number V28A
CLC020 SMPTE 259M Digital Video Serializer with Integrated Cable Driver
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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