Overview
The LM1881M-X/NOPB, produced by National Semiconductor (now part of Texas Instruments), is a video sync separator integrated circuit. This device is designed to extract timing information, including composite and vertical sync, burst or back porch timing, and odd and even field information from standard negative-going sync NTSC, PAL, and SECAM video signals. The LM1881 operates from a single supply voltage between 5-V DC and 12-V DC and can handle input signals with amplitudes from 0.5 V to 2 V peak-to-peak.
The LM1881 is capable of providing sync separation for non-standard, faster horizontal rate video signals and is particularly useful in applications where clean and reliable sync signals are necessary. It features edge-triggered vertical output and a default triggered vertical output for non-standard video signals, making it versatile for various video processing tasks.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Supply Voltage | 5 | - | 12 | V |
| Input Voltage (VCC = 5 V) | 0.5 | - | 2 | V p-p |
| Input Resistance | - | - | >10 kΩ | - |
| Power Supply Drain Current (VCC = 5 V) | 5.2 | 10 | - | mA |
| Operating Free-Air Temperature | 0 | - | 70 | °C |
| Output Sink Current (Pins 1, 3, 5) | - | - | 5 | mA |
| Output Sink Current (Pin 7) | - | - | 2 | mA |
| Package Dissipation | - | - | 1100 | mW |
Key Features
- AC Coupled Composite Input Signal: Handles input signals with amplitudes from 0.5 V to 2 V peak-to-peak.
- Composite Sync and Vertical Outputs: Provides separate outputs for composite sync and vertical sync signals.
- Odd and Even Field Output: Identifies which video field of an interlaced video source is present at the input.
- Burst Gate or Back Porch Output: Generates a burst gate or back porch timing signal.
- Edge Triggered Vertical Output: Vertical output is triggered on the rising edge of the first serration in the vertical sync period.
- Default Triggered Vertical Output: Produces a default vertical output if the rising edge of the serration pulse does not occur within the externally set delay period.
- Adjustable for Non-Standard Video Signals: Can be adjusted for source signals with line scan frequencies differing from standard rates.
Applications
- Video Cameras and Recorders: Used for sync signal extraction and processing in video recording devices.
- Broadcasting Systems: Employed in broadcasting equipment to ensure accurate and reliable sync signals.
- Set-Top Boxes: Utilized in set-top boxes for digital TV and other video processing tasks.
- Home Entertainment Systems: Found in various home entertainment systems such as DVD players and gaming consoles.
- Computing and Gaming Applications: Used in computing and gaming applications where video sync signals are critical.
Q & A
- What is the primary function of the LM1881M-X/NOPB?
The primary function of the LM1881M-X/NOPB is to extract timing information, including composite and vertical sync, burst or back porch timing, and odd and even field information from standard video signals.
- What are the supported video standards for the LM1881M-X/NOPB?
The LM1881M-X/NOPB supports NTSC, PAL, and SECAM video standards.
- What is the operating supply voltage range for the LM1881M-X/NOPB?
The operating supply voltage range for the LM1881M-X/NOPB is from 5 V to 12 V DC.
- How does the LM1881M-X/NOPB handle non-standard video signals?
The LM1881M-X/NOPB can be adjusted for non-standard video signals by using an external resistor (RSET) to set the internal current levels and adjust the timing.
- What are the key outputs provided by the LM1881M-X/NOPB?
The key outputs include composite sync output, vertical sync output, burst or back porch timing output, and odd and even field output.
- What is the purpose of the RSET resistor in the LM1881M-X/NOPB circuit?
The RSET resistor sets the internal current levels and affects the integrator and the internal oscillator, allowing for adjustments to be made for different line scan frequencies.
- How does the LM1881M-X/NOPB generate the vertical sync output?
The vertical sync output is generated on the rising edge of the first serration in the vertical sync period or by a default trigger if the serration pulse does not occur within the set delay period.
- What are some common applications of the LM1881M-X/NOPB?
Common applications include video cameras and recorders, broadcasting systems, set-top boxes, home entertainment systems, and computing and gaming applications.
- What is the maximum operating free-air temperature for the LM1881M-X/NOPB?
The maximum operating free-air temperature for the LM1881M-X/NOPB is 70°C.
- What is the package dissipation rating for the LM1881M-X/NOPB?
The package dissipation rating for the LM1881M-X/NOPB is 1100 mW.
