LMH1980
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SNLS263A –JULY 2007–REVISED MARCH 2013
LMH1980 Auto-Detecting SD/HD/PC Video Sync Separator
Check for Samples: LMH1980
1FEATURES DESCRIPTION
The LMH1980 is an auto-detecting SD/HD/PC video
2• Analog Video Sync Separation for NTSC, PAL, sync separator ideal for use in a wide range of video
480I/P, 576I/P, 720P, 1080I/P/PsF, and Many applications, such as automotive LCD monitors, video
VESA-Compatible Timing Formats capture & editing devices, surveillance & security
• Composite Video (CVBS), S-Video (Y/C), and equipment, and machine vision and inspection
Component Video (YPBPR/GBR) and PC systems.
Graphics (RGsB) Interfaces The LMH1980 accepts an analog video input signal
• SD/PC Bi-Level Sync & HD Tri-Level Sync with either bi-level or tri-level sync and automatically
Compatible detects the video format, eliminating the need for
external RSET resistor adjustment required by other
• Composite, Horizontal, and Vertical Sync sync separators (e.g.: LM1881). The outputs provide
Outputs timing signals in CMOS logic, including Composite,
• Burst/Back Porch Timing, Odd/Even Field, and Horizontal, and Vertical Syncs, Burst/Back Porch
HD Detect Flag outputs Timing, and Odd/Even Field outputs. The HD flag
• Automatic Video Format Detection output (pin 5) provides a logic low signal only when a
valid HD video input with tri-level sync is detected.
• Fixed-Level Sync Slicing for Video Inputs from The HD flag can be used to disable an external
0.5 to 2 VPP switch-controlled SD chroma filter when HD video is
• 3.3V to 5V Supply Operation detected, or enable it when SD video is detected. For
non-standard video with bi-level sync and without
APPLICATIONS vertical serration pulses, a default vertical sync pulse
will be output and no horizontal sync pulses will be
• Consumer, Professional, Automotive & output during the vertical sync interval.
Industrial Video The LMH1980 is available in a space-saving 10-lead
• Video Capture, Editing, and Processing Mini-SO Package (VSSOP) and operates over a
• Genlock Circuits temperature range of −40°C to +85°C.
• Surveillance & Security Video Systems
• Set-Top Boxes (STB) & Digital Video
Recorders (DVR)
• LCD / Plasma Displays and Video Projectors
• Machine Vision and Inspection Systems
• Video Trigger Oscilloscopes and Waveform
Monitors
1Please 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.
2All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date. Copyright © 2007–2013, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
REXT
GND
VCC
VIN
HD
OEOUT
BPOUT
CSOUT
VSOUT
HSOUT
LMH1980
1
2
3
4
5
10
9
8
7
6
LMH1980
SNLS263A –JULY 2007–REVISED MARCH 2013
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Connection Diagram
Top View
Figure 1. 10-Lead VSSOP Package
See Package Number DGS0010A
Pin Descriptions
Pin No. Pin Name Pin Description
1 REXT Bias Current External Resistor
2 GND Ground
3 VCC Supply Voltage
4 VIN Analog Video Input
5 HD HD Detect Flag Output
6 HSOUT Horizontal Sync Output
7 VSOUT Vertical Sync Output
8 CSOUT Composite Sync Output
9 BPOUT Burst/Back Porch Timing Output
10 OEOUT Odd/Even Field Output
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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)
ESD Tolerance (3) Human Body Model 3.5 kV
Machine Model 350V
Supply Voltage, VCC 0V to 5.5V
Video Input, VIN −0.3V to VCC + 0.3V
Storage Temperature Range −65°C to +150°C
Lead Temperature (soldering 10 sec.) 300°C
Junction Temperature, TJMAX(4) +150°C
Thermal Resistance, θJA (no airflow) 120°C/W
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test
conditions, see the Electrical Characteristics Tables.
(2) All voltages are measured with respect to GND, unless otherwise specified.
(3) Human Body Model, applicable std. MIL-STD-883, Method 3015.7. Machine Model, applicable std. JESD22-A115-A (ESD MM std. of
JEDEC)Field-Induced Charge-Device Model, applicable std. JESD22-C101-C (ESD FICDM std. of JEDEC).
(4) The maximum power dissipation is a function of TJ(MAX),θJA. The maximum allowable power dissipation at any ambient temperature is
PD= (TJ(MAX) - TA)/θJA . All numbers apply for packages soldered directly onto a PC board.
Operating Ratings (1)
Temperature Range (2) −40°C to +85°C
VCC 3.3V −10% to 5V +10%
Input Amplitude, VIN-AMPL 140 mV to VCC–VIN-CLAMP
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test
conditions, see the Electrical Characteristics Tables.
(2) The maximum power dissipation is a function of TJ(MAX),θJA. The maximum allowable power dissipation at any ambient temperature is
PD= (TJ(MAX) - TA)/θJA . All numbers apply for packages soldered directly onto a PC board.
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Electrical Characteristics (1)
Unless otherwise specified, all limits are specified for TA= 25°C, VCC = 3.3V, REXT = 10 kΩ1%, RL= 10 kΩ, CL< 10
pF.Boldface limits apply at the temperature extremes. See Figure 2 for Test Circuit.
Parameter Test Conditions Min (2) Typ (3) Max (2) Units
ICC Supply Current No input signal VCC = 3.3V 10.5 12.5 mA
VCC = 5V 12.0 14.0
Video Input Specifications
VIN-SYNC Input Sync Amplitude Amplitude from negative sync tip to video 0.14 0.30 0.60
blanking level for SD/EDTV bi-level sync (4)
(5) VPP
Amplitude from negative to positive sync tips 0.30 0.60 1.20
for HDTV tri-level sync (4) (6)
VIN-CLAMP Input Sync Tip Clamp Level (7) 0.7 V
VIN-SLICE Input Sync Slice Level Slicing level above VIN-CLAMP 70 mV
Logic Output Specifications (8)
VOL Output Logic 0 See output load conditions VCC = 3.3V 0.3 V
above VCC = 5V 0.5
VOH Output Logic 1 See output load conditions VCC = 3.3V 3.0 V
above VCC = 5V 4.5
TSYNC-LOCK Sync Lock Time Time for the output signals to be correct after 2 V
the video signal settles at VIN following a periods
significant input change. See START-UP
TIME for more information
TVSOUT Vertical Sync Output Pulse Serration Pulses in the Vertical Interval. See 3 H
Width Figure 3,Figure 4,Figure 5,Figure 6, periods
Figure 7, and Figure 8 for SDTV, EDTV &
HDTV Vertical Interval Timing
(1) Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very
limited self-heating of the device such that TJ= TA. Parametric performance indicated in the electrical tables is not ensured under
conditions of internal self-heating where TJ> TA.
(2) Limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlations using the
Statistical Quality Control (SQC) method.
(3) Typical values represent the most likely parametric norm at the time of characterization. Actual typical values may vary over time and
will also depend on the application and configuration. The typical values are not tested and are not specified on shipped production
material.
(4) VIN-AMPL plus VIN-CLAMP should not exceed VCC.
(5) Tested with 480I signal.
(6) Tested with 1080P signal.
(7) Maximum voltage offset (DC bounce) between 2 consecutive input sync tips must be less than 25 mVPP; otherwise, this may cause
incorrect output signals to occur.
(8) Outputs are negative-polarity logic signals, except for Odd/Even Field.
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VIN
CSOUT
HSOUT
BPOUT
VSOUT
OEOUT
COLOR
BURST
START OF FIELD 1
ODD FIELD
LINE # 1 3 4 5 6 7 9 10 11525 2 8
3H
H
3H 3H
TVSOUT = 3H
H½ H
VERTICAL SYNC
SERRATION
TP2
Odd/Even
Field Output
2
1
TP3
Burst/Back
Porch Output
2
1
TP4
Composite
Sync Output
2
1
TP5
Vertical Sync
Output
2
1
TP6
Horizontal
Sync Output
2
1
R6
100:
R7
100:
R8
100:
R4
100:
R5
100:
7
6
8
9
10
OEOUT
BPOUT
CSOUT
VSOUT
HSOUT
LMH1980
4
5
3
2
1REXT
GND
VCC
VIN
HD
U2
R2
10 k:
1%
C5
0.1 PF
C3
0.1 PF
+
C4
10 PF
R3
10 k:
R10
100:
TP1
HD Detect Flag Output
2
1
J2
GND TP7
GND
1
1
J1
VCC TP8
VCC
1
1
R9
100:
C2
560 pF
C1
*OPT
Q1
MMBT3904
R1
75:
BNC
J3
LMH1980
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SNLS263A –JULY 2007–REVISED MARCH 2013
LMH1980 Test Circuit
Figure 2. Test Circuit
The LMH1980 test circuit is shown in Figure 2. The video generator should provide a clean, low-noise video input
signal with minimal sync pulse overshoot over 75Ωcoaxial cable, which should be impedance-matched with a
75Ωload termination resistor to prevent unwanted signal distortion. The output waveforms should be monitored
using a low-capacitance probe on an oscilloscope with at least 500 MHz bandwidth. See PCB LAYOUT
CONSIDERATIONS for more information about signal and supply trace routing and component placement. Also,
refer to the “LMH1980 Evaluation Board Instruction Manual” Application Note (AN-1618 [SNLA096]).
SDTV Vertical Interval Timing Diagrams (NTSC, PAL, 480I, 576I)
Figure 3. NTSC Odd Field Vertical Interval
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VIN
CSOUT
HSOUT
BPOUT
VSOUT
OEOUT
START OF FRAME
OEOUT LOGIC HIGH FOR PROGRESSIVE VIDEO
FORMATS
VERTICAL SYNC SERRATION
TVSOUT = 3H
6H 6H
H
|
|||
H
|
1 6 7 8 9 10 11 12 13 14
525
LINE #
|
VIN
CSOUT
HSOUT
BPOUT
VSOUT
OEOUT
264 265 266 267 268 269 270 271 272 273
EVEN FIELD
½ H
LINE # 263
START OF FIELD 2
3H 3H 3H
TVSOUT = 3H
LMH1980
SNLS263A –JULY 2007–REVISED MARCH 2013
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Figure 4. NTSC Even Field Vertical Interval
EDTV Vertical Interval Timing Diagram (480P, 576P)
Figure 5. 480P Vertical Interval
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1
VIN
CSOUT
HSOUT
BPOUT
VSOUT
OEOUT
3 4 5 6 7 20 21 22
1125
FIELD 1
2
VERTICAL
SYNC SERRATION
TVSOUT = 3H
||
|
||
|
H15H
LINE #
½ H
START OF FIELD 1
1
VIN
CSOUT
HSOUT
BPOUT
VSOUT
OEOUT
3 4 5 6 7 25
(41) 26
(42) 27
(43)
750
(1125)
OEOUT LOGIC HIGH FOR
PROGRESSIVE VIDEO FORMATS
2
TVSOUT = 3H
|
|
||
|
H20H (36H)
LINE #
START OF FRAME
|
8...
LMH1980
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SNLS263A –JULY 2007–REVISED MARCH 2013
HDTV Vertical Interval Timing Diagram (720P, 1080P)
Figure 6. 720P (1080P) Vertical Interval
HDTV Vertical Interval Timing Diagrams (1080I)
Figure 7. 1080I Field 1 Vertical Interval
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VIN
CSOUT
HSOUT
BPOUT
SYNC TIP LEVEL
BLANKING LEVEL
WHITE LEVEL
VIDEO
SYNC
50%
THSOUT
tdBPOUT
tdHSOUT
tdCSOUT
0.5 VPP to 2 VPP
1 VPP (typ.)
TBPOUT
VIDEO INPUT RANGE
OH
NTSC/PAL
COLOR BURST
ENVELOPE
LMH1980
SNLS263A –JULY 2007–REVISED MARCH 2013
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Figure 8. 1080I Field 2 Vertical Interval
SD/EDTV Horizontal Interval Timing Diagram
Figure 9. SD/EDTV Horizontal Interval with Bi-level Sync
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Table 1. SDTV Horizontal Interval Timing Characteristics(1)
Parameter Test Conditions Typ Units
tdCSOUT Composite Sync Output See Figure 9 525
Propagation Delay from ns
Input Sync Reference
(OH)
tdHSOUT Horizontal Sync Output See Figure 9 530
Propagation Delay from ns
Input Sync Reference
(OH)
tdBPOUT Burst/Back Porch Timing See Figure 9 400 ns
Output Propagation Delay
from Input Sync Trailing
Edge
THSOUT Horizontal Sync Output See Figure 9 2.5 µs
Pulse Width
TBPOUT Burst/Back Porch Timing See Figure 9 3.0 µs
Output Pulse Width
(1) VCC = 3.3V , TA= 25°C, No Input Filter, PAL Video Input from Tek TG700 Generator with AVG7 SD video module
Table 2. EDTV Horizontal Interval Timing Characteristics(1)
Parameter Test Conditions Typ Units
tdCSOUT Composite Sync Output See Figure 9 170 ns
Propagation Delay from
Input Sync Reference
(OH)
tdHSOUT Horizontal Sync Output See Figure 9 175 ns
Propagation Delay from
Input Sync Reference
(OH)
tdBPOUT Burst/Back Porch Timing See Figure 9 485 ns
Output Propagation Delay
from Input Sync Trailing
Edge
THSOUT Horizontal Sync Output See Figure 9 2.3 µs
Pulse Width
TBPOUT Burst/Back Porch Timing See Figure 9 350 ns
Output Pulse Width
(1) VCC = 3.3V , TA= 25°C, No Input Filter, 576P Video Input from Tek TG700 Generator with AVG7 SD module
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VIN
CSOUT
HSOUT
BPOUT
TBPOUT
BLANKING LEVEL
WHITE LEVEL
- SYNC
OHTRAILING
EDGE
50%
50%
50% + SYNC
VIDEO
tdBPOUT
THSOUT
tdHSOUT
tdCSOUT
VIDEO INPUT RANGE
0.5 VPP to 2 VPP
1 VPP (typ.)
LEADING
EDGE
LMH1980
SNLS263A –JULY 2007–REVISED MARCH 2013
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HDTV Horizontal Interval Timing Diagram
Figure 10. HDTV Horizontal Interval with Tri-level Sync
Table 3. HDTV Horizontal Interval Timing Characteristics(1)
Parameter Test Conditions Typ Units
tdCSOUT Composite Sync Output See Figure 10 150 ns
Propagation Delay from
Input Sync Leading Edge
tdHSOUT Horizontal Sync Output See Figure 10 60 ns
Propagation Delay from
Input Sync Reference
(OH)
tdBPOUT Burst/Back Porch Timing See Figure 10 450
Output Propagation Delay ns
from Input Sync Trailing
Edge
THSOUT Horizontal Sync Output See Figure 10 525 ns
Pulse Width
TBPOUT Burst/Back Porch Timing See Figure 10 350 ns
Output Pulse Width
(1) VCC = 3.3V , TA= 25°C, No Input Filter, 1080I Video Input from Tek TG700 Generator with AWVG7 HD module
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APPLICATION INFORMATION
GENERAL DESCRIPTION
The LMH1980 is designed to extract the timing information from various video formats with standard and non-
standard vertical serration and output the syncs and relevant timing signals in CMOS logic. Its advanced features
and easy application make it ideal for consumer, professional, and industrial video systems where sync timing
needs to be extracted from SD, HD, and PC video signals. The device can operate from a supply voltage
between 3.3V and 5V. The only required external components are bypass capacitors between the VCC and GND
pins, input coupling capacitor (CIN) from the signal source to the VIN pin, and a fixed-value 1% precision resistor
between the REXT and GND pins. Refer to the test circuit in Figure 2.
REXT Resistor
The precision external resistor (REXT) establishes the internal bias current and precise reference voltage for the
LMH1980. For optimal performance, REXT should be a 10 kΩ1% precision resistor with a low temperature
coefficient to ensure proper operation over a wide temperature range. Using a REXT resistor with less precision
may result in reduced performance (like worse performance, increased propagation delay variation, or reduced
input sync amplitude range) against temperature, supply voltage, input signal, or part-to-part variations.
NOTE
The REXT resistor used with the LMH1980 serves a different function than the “RSET
resistor” used with other previous sync separators, like the LM1881. For the LM1881, the
RSET value needed to be adjusted externally to support different input line rates. For the
LMH1980, the REXT value is fixed, and the device automatically detects the input line rate
to support various video formats without electrical or physical intervention.
Automatic Format Detection and Switching
Automatic format detection eliminates the need for adjusting an external RSET resistor or programming via a
microcontroller. The device outputs will respond correctly to a switch in video format after a sufficient start-up
time has been satisfied, usually within 1 to 2 fields of video. Unlike other sync separators, the LMH1980 does not
require the power to be cycled in order to produce correct outputs after a significant change to the input signal.
See START-UP TIME for more details.
Fixed-Level Sync Slicing
The LMH1980 uses fixed-level sync slicing for video inputs with an amplitude from 0.5VPP to 2VPP, which allows
for proper sync separation even for improperly terminated or attenuated input signals. The fixed-level sync slicing
threshold is nominally 70 mV above the clamped sync tip. This means that for a minimum video input signal
amplitude of 0.5VPP, the slicing level is near the mid-point of the sync pulse amplitude. This slicing level is
independent of the input signal amplitude; therefore, for a 2VPP input, the slicing level occurs at 12% of the sync
pulse amplitude.
INPUT CONSIDERATIONS
The LMH1980 supports sync separation for analog CVBS, Y (luma) from Y/C and YPBPR, and G (sync on green)
from GBR/RGsB, as specified in the following video standards.
• Composite Video (CVBS) and S-Video (Y/C):
– SMPTE 170M (NTSC), ITU-R BT.470 (PAL)
• Component Video (YPBPR/GBR):
– SDTV: SMPTE 125M, SMPTE 267M, ITU-R BT.601 (480I, 576I)
– EDTV: ITU-R BT.1358 (480P, 576P)
– HDTV: SMPTE 296M (720P), SMPTE 274M (1080I/P), SMPTE RP 211 (1080PsF)
• PC Graphics (RGsB):
– VESA Monitor Timing Standards and Guidelines Version 1.0, Revision 0.8
•Non-Standard Video:
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7
6
VSOUT
HSOUT
4
5
VIN
HD
C5
0.1 PF
R3
10 k:
R10
100:
TP1
HD Detect Flag Output
2
1
R9
100:
C2
560 pF
C1
*OPT
Q1
MMBT3904
R1
75:
BNC
J3
LMH1980
SNLS263A –JULY 2007–REVISED MARCH 2013
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– Composite NTSC & PAL (or Component 480I & 576I) without vertical serration & equalization pulses (i.e.:
from logical OR-ing of H & V signals)
Input Termination
The video source should be load terminated with a 75Ωresistor to ensure correct video signal amplitude and
minimize signal distortion due to reflections. In extreme cases, the LMH1980 can handle non-terminated or
double-terminated input conditions, assuming 1VPP signal amplitude for normally terminated video.
Input Filtering
An external filter is recommended if the video signal has large chroma amplitude that extends near the sync tip
and/or has considerable high-frequency noise, so they do not interfere with sync separation. A simple RC low-
pass chroma filter with a series resistor (R9) and a filter capacitor (C2) to ground can be used to sufficiently
attenuate chroma such that minimum peak of its amplitude is above the slicing level and also to improve the
overall signal-to-noise ratio. To achieve the desired filter cutoff frequency, it’s advised to vary C2and keep R9
small (i.e.: 100Ω) to minimize sync tip clipping due to the voltage drop across R9. Keep in mind that as the cutoff
frequency decreases, the LMH1980 output propagation delays increase, which could affect the timing
relationship between the sync and video signals.
In applications where the chroma filter needs to be disabled when HD video is input, it is possible to use a
transistor switch (Q1) controlled by the HD flag (pin 5) to open C2’s connection to ground as shown in Figure 11.
When a HD tri-level sync input signal is applied, HD will output logic low (following a brief delay for auto format
detection) and Q1 will turn off to disable the chroma filter, which is intended for SD composite video only. When
a SD bi-level sync signal (i.e.: NTSC/PAL) is applied, HD will output logic high and Q1 will turn on to enable the
chroma filter.
Important: If the filter cutoff frequency (fCO) is set too low and HD video is applied, the filter can severely roll off
and attenuate the input's high-bandwidth tri-level sync pulses such that the LMH1980 cannot detect a valid HD
input signal. If the LMH1980 cannot detect a valid HD input, then the HD flag will never change from logic high to
low and the switch-controlled filter will never be disabled via Q1. In other words, fCO should not be set too low
that the filter impairs the LMH1980's ability to detect a valid HD input. The values of R9and C2shown in
Figure 11 give fCO=2.79 MHz (about -4 dB at 3.58 MHz NTSC subcarrier frequency) without impairing HD video
format detection.
Figure 11. External Switch-Controlled Chroma Filter
If a PC video input with bi-level sync is to be used, C2should be removed to disable chroma filtering. This is
necessary because HD will output logic high (like in the SD video input case) and enable the filter. A chroma
filter could severely band-limit a high-bandwidth PC video signal, which could roll-off and attenuate the sync
pulses such that the LMH1980 cannot detect a valid input signal.
If some high-frequency noise filtering is needed for all video inputs, a small capacitor (C1) may be optionally used
in parallel but outside of the transistor switch. When Q1 is turned on, then C1and C2will be connected in parallel
(C1+C2)
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Input Coupling Capacitor
The input signal should be AC coupled to the VIN (pin 4) of the LMH1980 with a properly chosen coupling
capacitor, CIN.
The primary consideration in choosing CIN is whether the LMH1980 will interface with video sources using an
AC-coupled output stage. If AC-coupled video sources are expected in the end-application , then it’s
recommended to choose a small CIN value such as 0.01 µF to avoid missing sync output pulses due to average
picture level changes. It’s important to note that video sources with an AC-coupled output will cause video-
dependent jitter at the HSync output of the sync separator. When only DC-coupled video sources are expected, a
larger value for CIN may be used without concern for missing sync output pulses. A smaller CIN value can be
used to increase rejection of source AC hum components and also reduce start-up time regardless of the video
source's output coupling type.
START-UP TIME
When there is a significant change to the video input signal, such as sudden signal switching in, signal
attenuation (i.e.: load termination added via loop through) or signal gain (i.e.: load termination removed), the
quiescent operation of the LMH1980 will be disrupted. During this dynamic input condition, the LMH1980 outputs
may not be correct but will recover to valid signals after a predictable start-up time, which consists of an
adjustable input settling time and a predetermined “sync lock time”.
Input Settling Time and Coupling Capacitor Selection
Following a significant input condition, the negative sync tip of the AC-coupled signal settles to the input clamp
voltage as the coupling capacitor, CIN, recovers a quiescent DC voltage via the dynamic clamp current through
VIN. Because CIN determines the input settling time, its capacitance value is critical when minimizing overall start-
up time. A smaller CIN value yields shorter settling time at the expense of increased line droop voltage, whereas
a larger one yields reduced line droop but longer settling time. Settling time is proportional to the value of CIN, so
doubling CIN will also double the settling time.
Sync Lock Time
In addition to settling time, the LMH1980 has a predetermined sync lock time, TSYNC-LOCK, before the outputs are
correct. Once the AC-coupled input has settled enough, the LMH1980 needs time to detect the valid video signal
and apply fixed-level sync slicing before the output signals are correct.
For practical values of CIN, TSYNC-LOCK is typically less than 1 or 2 video fields in duration starting from the 1st
valid VSync output pulse to the valid HSync pulses beginning thereafter. VSync and HSync pulses are
considered valid when they align correctly with the input's vertical and horizontal sync intervals.
It is recommended for the outputs to be applied to the system after the start-up time is satisfied and outputs are
valid. For example, the oscilloscope screenshot in Figure 12 shows a typical start-up time within 1 video field
from when an NTSC signal is just applied to when the LMH1980 outputs are valid.
Figure 12. Typical Start-Up Time for NTSC Input to LMH1980 (CIN = 0.1 µF)
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LOGIC OUTPUTS
In the absence of a video input signal, the LMH1980 outputs are logic high except for the odd/even field, which is
undefined and depends on its previous state, and the composite sync output.
Horizontal Sync Output
HSOUT (pin 6) produces a negative-polarity horizontal sync signal, or HSync, extracted from the input signal. For
bi-level and tri-level sync signals, HSync's negative-going leading edge is derived from the input's sync
reference, OH, with a propagation delay.
Important: The HSync output has good performance on its negative-going leading edge, so it should be used as
the reference to a negative-edge triggered PLL input. If HSync is used as the reference to a positive-edge
triggered PLL input, like in some FPGAs, the signal must be inverted first to produce a positive-polarity HSync
signal (i.e.: positive-going leading edge) before the PLL input. HSync's trailing edge should not be used as the
reference to a PLL because for a NTSC/PAL input, the input's half-width pulses (½TSYNC) in the vertical interval
cause the trailing edges of the HSync output to occur earlier than for the normal-width sync pulses (TSYNC). This
bi-modal timing variation on HSync's trailing edge, as shown in Figure 13, could affect the performance of the
PLL. The bi-modal trailing edge timing also occurs on the CSync output as well.
Figure 13. Bi-modal Timing on HSync's Trailing Edge for Half-Width Pulses for NTSC
Vertical Sync Output
VSOUT (pin 7) produces a negative-polarity vertical sync signal, or VSync. VSync's negative-going leading edge
is derived from the first vertical serration pulse with a propagation delay, and its output pulse width, TVSOUT,
spans approximately three horizontal periods (3H). When there is no vertical serration pulses (i.e.: non-standard
video signal), the LMH1980 will output a default VSync pulse derived from the input's vertical sync leading edge
with a propagation delay.
Composite Sync Output
CSOUT (pin 8) simply reproduces the video input sync pulses below the video blanking level. This is obtained by
clamping the video signal sync tip to the internal clamp voltage at VIN and extracting the resultant composite sync
signal, or CSync. For both bi-level and tri-level syncs, CSync's negative-going leading edge is derived from the
input's negative-going leading edge with a propagation delay.
Burst/Back Porch Timing Output
BPOUT (pin 9) provides a negative-polarity burst/back porch signal, which is pulsed low for a fixed width during
the back porch interval following the input's sync pulse. The burst/back porch timing pulse is useful as a burst
gate signal for NTSC/PAL color burst synchronization and as a clamp signal for black level clamping (DC
restoration) and sync stripping applications.
14 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated
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SNLS263A –JULY 2007–REVISED MARCH 2013
For SDTV formats, the back porch pulse's negative-going leading edge is derived from the input's positive-going
sync edge with a propagation delay, and the pulse width spans an appropriate duration of the color burst
envelope for NTSC/PAL. For EDTV formats, the back porch pulse behaves similar to the SDTV case except with
a narrow pulse width. For HDTV formats, the pulse's leading edge is derived from the input's negative-going
trailing sync edge with a propagation delay, and the pulse width is narrow to correspond with the short back
porch durations. During the vertical sync period, the back porch output will be muted (no pulses) and remain
logic high.
Odd/Even Field Output
OEOUT (pin 10) provides an odd/even field output signal, which facilitates identification of odd and even fields for
interlaced or segmented frame (sF) formats. For interlaced or segmented frame formats, the odd/even output is
logic high during an odd field (field 1) and logic low during an even field (field 2). The odd/even output edge
transitions align with VSync's leading edge to designate the start of odd and even fields. For progressive (non-
interlaced) video formats, the output is held constantly at logic high.
HD Detect Flag Output
HD (pin 5) is an active-low flag output that only outputs a logic low signal when a valid HD video input (i.e.: 720P,
1080I and 1080P) with tri-level sync is detected; otherwise, it will output logic high. Note that there is a
processing delay (within 1 to 2 video fields) from when an HD video signal is applied to when the outputs are
correct and the HD flag changes from logic high (default) to logic low, to indicate a valid HD input has been
detected.
The HD flag can be used to disable an external switch-controlled SD chroma filter when HD video is detected
and conversely, enable it when SD video is detected. This is important because a non-switched chroma filter
attenuates signal components above 500 kHz to 3 MHz, which could roll-off and/or attenuate the high bandwidth
HD tri-level sync signal prior to the LMH1980 and may increase output propagation delay and jitter. SeeInput
Filtering for more information.
ADDITIONAL CONSIDERATIONS
Using an AC-Coupled Video Source into the LMH1980
An AC coupled video source typically has a 100 µF or larger output coupling capacitor (COUT) for protection and
to remove the DC bias of the amplifier output from the video signal. When the video source is load terminated,
the average value of the video signal will shift dynamically as the video duty cycle varies due to the averaging
effect of the COUT and termination resistors. The average picture level or APL of the video content is closely
related to the duty cycle.
For example, a significant decrease in APL such as a white-to-black field transition will cause a positive-going
shift in the sync tips characterized by the source’s RC time constant, tRC-OUT (150Ω*COUT). The LMH1980’s input
clamp circuitry may have difficulty stabilizing the input signal under this type of shifting; consequently, the
unstable signal at VIN may cause missing sync output pulses to result, unless a proper value for CIN is chosen.
To avoid this potential problem when interfacing AC-coupled sources to the LMH1980, it’s necessary to introduce
a voltage droop component via CIN to compensate for video signal shifting related to changes in the APL. This
can be accomplished by selecting CIN such that the effective time constant of the LMH1980’s input circuit, tRC-IN,
is less than tRC-OUT.
The effective time constant of the input circuit can be approximated as: tRC-IN = (RS+RI)*CIN*TLINE/TCLAMP, where
RS= 150Ω, RI=1kΩ(input resistance when clamping), TLINE ∼64 μs for NTSC, and TCLAMP = 250 ns (internal
clamp duration). A white-to-black field transition in NTSC video through COUT will exhibit the maximum sync tip
shifting due to its long line period (TLINE). By setting tRC-IN < tRC-OUT, the maximum value of CIN can be calculated
to ensure proper operation under this worst-case condition.
For instance, tRC-OUT is about 33 ms for COUT = 220 µF. To ensure tRC-IN < 33 ms, CIN must be about 100 nF or
less. By choosing CIN = 47 nF, the LMH1980 will function properly with AC-coupled video sources using COUT ≥
220 μF.
Copyright © 2007–2013, Texas Instruments Incorporated Submit Documentation Feedback 15
Product Folder Links: LMH1980
LMH1980
SNLS263A –JULY 2007–REVISED MARCH 2013
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PCB LAYOUT CONSIDERATIONS
Please refer to the “LMH1980 Evaluation Board Instruction Manual” Application Note (AN-1618 [SNLA096]) for a
good PCB layout example, which adheres to the following suggestions for component placement and signal
routing.
LMH1980 IC Placement
The LMH1980 should be placed such that critical signal paths are short and direct to minimize PCB parasitics
from degrading the video input and logic output signals.
Ground Plane
A two-layer, FR-4 PCB is sufficient for this device. One of the PCB layers should be dedicated to a single, solid
ground plane that connects to the GND pin of the device and connects to other components, serving as the
common ground reference. It also helps to reduce trace inductances and minimize ground loops. Routing supply
and signal traces on another layer can help to maintain as much ground plane continuity as possible.
Power Supply Routing
The power supply pin should be connected using short traces with minimal inductance. When routing the supply
traces, try not to disrupt the solid ground plane.
For high frequency bypassing, place 0.1 µF and 0.01 µF SMD ceramic bypass capacitors with very short
connections to VCC and GND pins. Place a 4.7 or 10 µF SMD tantalum bypass capacitor nearby the VCC for low
frequency supply bypassing.
REXT Resistor
The REXT resistor should be a 10 kΩ1% SMD precision resistor. Place REXT as close as possible to the device
and connect to pin 1 and the ground plane using the shortest possible connections. All input and output signals
should be kept as far as possible from this pin to prevent unwanted signals from coupling into this bias reference
pin.
Video Input
The input signal path should be routed using short, direct traces between video source and input pin. Use a 75Ω
load termination on the board, if not on the cable. If applicable, the chroma filter components should be
connected using short traces and the filter capacitor should be connected to the ground plane. There should be a
sufficient return path from the LMH1980 back to the input source via the ground plane.
Output Routing
The output signal paths should be routed using short, direct traces to minimize parasitic effects that may degrade
these high-speed logic signals. The logic outputs do not have high output drive capability. Each output should
have a resistive load of about 10kΩor more and capacitive load of about 10pF including parasitic capacitances
for optimal signal quality. Each output can be protected against brief short-circuit events using a small series
resistor, like 100Ω, to limit output current.
16 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated
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LMH1980
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SNLS263A –JULY 2007–REVISED MARCH 2013
REVISION HISTORY
Changes from Original (March 2013) to Revision A Page
• Changed layout of National Data Sheet to TI format .......................................................................................................... 16
Copyright © 2007–2013, Texas Instruments Incorporated Submit Documentation Feedback 17
Product Folder Links: LMH1980
PACKAGE OPTION ADDENDUM
www.ti.com 10-Dec-2020
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LMH1980MM/NOPB ACTIVE VSSOP DGS 10 1000 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 AL4A
LMH1980MMX/NOPB ACTIVE VSSOP DGS 10 3500 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 AL4A
(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 <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
PACKAGE OPTION ADDENDUM
www.ti.com 10-Dec-2020
Addendum-Page 2
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
LMH1980MM/NOPB VSSOP DGS 10 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
LMH1980MMX/NOPB VSSOP DGS 10 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 21-Mar-2013
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
LMH1980MM/NOPB VSSOP DGS 10 1000 210.0 185.0 35.0
LMH1980MMX/NOPB VSSOP DGS 10 3500 367.0 367.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 21-Mar-2013
Pack Materials-Page 2
www.ti.com
PACKAGE OUTLINE
C
TYP
5.05
4.75
1.1 MAX
8X 0.5
10X 0.27
0.17
2X
2
0.15
0.05
TYP
0.23
0.13
0 - 8
0.25
GAGE PLANE
0.7
0.4
A
NOTE 3
3.1
2.9
B
NOTE 4
3.1
2.9
4221984/A 05/2015
VSSOP - 1.1 mm max heightDGS0010A
SMALL OUTLINE PACKAGE
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not
exceed 0.15 mm per side.
4. This dimension does not include interlead flash. Interlead flash shall not exceed 0.25 mm per side.
5. Reference JEDEC registration MO-187, variation BA.
110
0.1 C A B
6
5
PIN 1 ID
AREA
SEATING PLANE
0.1 C
SEE DETAIL A
DETAIL A
TYPICAL
SCALE 3.200
www.ti.com
EXAMPLE BOARD LAYOUT
(4.4)
0.05 MAX
ALL AROUND 0.05 MIN
ALL AROUND
10X (1.45)
10X (0.3)
8X (0.5)
(R )
TYP
0.05
4221984/A 05/2015
VSSOP - 1.1 mm max heightDGS0010A
SMALL OUTLINE PACKAGE
SYMM
SYMM
LAND PATTERN EXAMPLE
SCALE:10X
1
56
10
NOTES: (continued)
6. Publication IPC-7351 may have alternate designs.
7. Solder mask tolerances between and around signal pads can vary based on board fabrication site.
METAL
SOLDER MASK
OPENING
NON SOLDER MASK
DEFINED
SOLDER MASK DETAILS
NOT TO SCALE
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
SOLDER MASK
DEFINED
www.ti.com
EXAMPLE STENCIL DESIGN
(4.4)
8X (0.5)
10X (0.3)
10X (1.45)
(R ) TYP0.05
4221984/A 05/2015
VSSOP - 1.1 mm max heightDGS0010A
SMALL OUTLINE PACKAGE
NOTES: (continued)
8. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
9. Board assembly site may have different recommendations for stencil design.
SYMM
SYMM
1
56
10
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
SCALE:10X
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