Overview
The LM1881MX/NOPB, produced by Texas Instruments, is a video sync separator integrated circuit designed to extract timing information from composite video signals. This device supports standard negative-going sync signals for NTSC, PAL, and SECAM video formats. It operates from a single supply voltage between 5-V DC and 12-V DC and requires minimal external components, including a power supply decoupling capacitor, a composite input coupling capacitor, and an external resistor (RSET) to set internal current levels.
The LM1881MX/NOPB is capable of providing composite sync, vertical sync, burst gate or back porch timing, and odd and even field outputs. It is particularly useful in applications requiring the separation of sync signals from composite video sources, such as video cameras, recorders, broadcasting systems, and home entertainment devices.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Supply Voltage | 5 | - | 12 | V |
| Input Voltage (VCC = 5) | 0.5 | - | 3 | Vp-p |
| Input Voltage (VCC ≥ 8) | 0.5 | - | 6 | Vp-p |
| Operating Temperature | 0 | - | 70 | °C |
| Supply Current (VCC = 5 V) | 5.2 | 10 | - | mA |
| Output Sink Current (Pins 1, 3, 5) | - | - | 5 | mA |
| Output Sink Current (Pin 7) | - | - | 2 | mA |
| ESD Rating (Human Body Model) | - | - | ±2000 | V |
Key Features
- AC Coupled Composite Input Signal: Supports input signals with amplitudes from 0.5 V to 2 V p-p.
- Sync Outputs: Provides composite sync, vertical sync, burst gate or back porch timing, and odd and even field outputs.
- Adjustable RSET: Allows adjustment for source signals with different line scan frequencies.
- Default Vertical Sync Output: Generates a default vertical sync pulse for non-standard video signals.
- Low Power Consumption: Supply current is typically 10 mA at VCC = 5 V.
- High Input Resistance: Input resistance greater than 10 kΩ.
- Support for Various Video Standards: Compatible with NTSC, PAL, and SECAM video formats.
Applications
- Video Cameras and Recorders: Useful for gen-locking video camera/VTR signals with graphics sources.
- Broadcasting Systems: Essential for extracting timing information in broadcasting environments.
- Set-Top Boxes: Applied in set-top boxes for video signal processing.
- Home Entertainment: Used in various home entertainment devices such as TVs and gaming consoles.
- Computing and Gaming: Utilized in computing and gaming applications requiring video signal synchronization.
Q & A
- What is the primary function of the LM1881MX/NOPB?
The primary function of the LM1881MX/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 formats for the LM1881MX/NOPB?
The LM1881MX/NOPB supports NTSC, PAL, and SECAM video formats.
- What is the operating voltage range for the LM1881MX/NOPB?
The operating voltage range is from 5 V to 12 V DC.
- What is the purpose of the RSET resistor in the LM1881MX/NOPB circuit?
The RSET resistor sets the internal current levels and allows adjustment for source signals with different line scan frequencies.
- How does the LM1881MX/NOPB handle non-standard video signals?
The LM1881MX/NOPB generates a default vertical sync pulse for non-standard video signals when the vertical sync period is unusually long and lacks serration pulses.
- What are the typical applications of the LM1881MX/NOPB?
Typical applications include video cameras, recorders, broadcasting systems, set-top boxes, home entertainment devices, and computing and gaming systems.
- What is the maximum ESD rating for the LM1881MX/NOPB?
The maximum ESD rating is ±2000 V according to the Human Body Model.
- What is the input resistance of the LM1881MX/NOPB?
The input resistance is greater than 10 kΩ.
- How does the LM1881MX/NOPB identify odd and even video fields?
The LM1881MX/NOPB provides an odd and even field output that identifies which video field of an interlaced video source is present at the input.
- What is the typical supply current of the LM1881MX/NOPB at VCC = 5 V?
The typical supply current is 10 mA at VCC = 5 V.
