LM2889 Technical Summary

Overview

The LM2889 is a specialized integrated circuit designed to interface audio and video signals with the antenna terminals of a television receiver. It integrates multiple functional blocks, including a sound subcarrier oscillator, FM modulator, video clamp, and RF oscillators and modulators for low-VHF applications. This component is particularly suited for broadcast and consumer electronics applications where reliable signal modulation and transmission are required.

With its pin-for-pin compatibility with the LM1889 RF section, the LM2889 offers an easy upgrade path for legacy designs. It operates within a supply voltage range of 10V to 16V, making it versatile for various system configurations. The device is known for its excellent oscillator stability, low distortion, and minimal intermodulation products, ensuring high-quality signal transmission.

Features

• Pin-for-Pin Compatibility: Direct replacement for the LM1889 RF section, simplifying design upgrades.
• Low Distortion FM Sound Modulator: Achieves less than 1% Total Harmonic Distortion (THD) for high-fidelity audio transmission.
• Video Clamp: Supports AC-coupled video signals, ensuring stable video output.
• Low Sound Oscillator Harmonic Levels: Minimizes unwanted harmonics for cleaner signal output.
• Wide Supply Voltage Range: Operates from 10V to 16V, accommodating various power supply configurations.
• DC Channel Switching: Enables straightforward channel selection and control.
• Excellent Oscillator Stability: Ensures consistent performance over temperature and time.
• Low Intermodulation Products: Reduces signal interference for clearer audio and video output.

Applications

The LM2889 is ideal for a variety of applications in consumer and professional electronics, including:

• Television Broadcast Equipment: Used to modulate audio and video signals for transmission.
• Cable TV Systems: Facilitates signal distribution across cable networks.
• Video Game Consoles: Provides RF modulation for older gaming systems requiring analog TV output.
• VCRs and DVD Players: Enables RF output for compatibility with older television sets.
• Educational and Industrial Video Systems: Supports signal modulation for closed-circuit TV and training systems.

Electrical Characteristics

Absolute Maximum Ratings

The following table outlines the absolute maximum ratings for the LM2889. Exceeding these values may result in permanent damage to the device.

• Supply Voltage (VCC): 16V
• Operating Temperature Range: -20°C to +75°C
• Storage Temperature Range: -55°C to +150°C
• Power Dissipation: 1.2W (at 25°C free-air temperature)

Recommended Operating Conditions

• Supply Voltage (VCC): 10V to 16V
• Ambient Temperature: 0°C to 70°C

Key Performance Parameters

• FM Sound Modulator THD: <1% (typical)
• Sound Subcarrier Frequency: 4.5MHz (standard)
• Video Input Level: 1Vpp (nominal)
• RF Output Level: Adjustable via external components

Package Information

The LM2889 is available in a standard 14-pin Dual-In-Line Package (DIP), designated as N14A. Below are the key package specifications:

• Package Type: N14A (14-pin DIP)
• Dimensions: 19.3mm x 6.35mm (body)
• Pin Spacing: 2.54mm (standard DIP pitch)
• Material: Molded plastic, lead-free options available

Pin Configuration

The pinout for the LM2889 is as follows:

• Pin 1: Video Input
• Pin 2: Video Clamp
• Pin 3: Ground
• Pin 4: Sound Subcarrier Output
• Pin 5: RF Oscillator Tank
• Pin 6: RF Output
• Pin 7: VCC (Supply Voltage)
• Pins 8-14: Additional control and modulation pins (see datasheet for full details)

Conclusion

The LM2889 is a robust and versatile IC designed for audio and video signal modulation in television and broadcast applications. Its low distortion, excellent stability, and wide operating voltage range make it a reliable choice for both consumer and professional electronics. With its pin-for-pin compatibility with the LM1889, it offers an easy transition for legacy designs while providing enhanced performance characteristics.

For detailed application notes, schematics, and additional performance data, refer to the official LM2889 datasheet from National Semiconductor Corporation.