LM567 Tone Decoder IC

LM567 Tone Decoder IC

The LM567 is a versatile tone decoder and phase-locked loop (PLL) IC designed for detecting and demodulating specific frequencies in analog and digital systems. Developed by Texas Instruments / National Semiconductor, this IC combines a voltage-controlled oscillator (VCO) and a phase detector in a single package, allowing it to lock onto an input signal’s frequency and provide a digital output when a match occurs.

The LM567 is widely used in tone detection, frequency monitoring, remote control systems, data transmission, and tone-based signaling applications. Its high sensitivity, wide frequency range, and excellent noise immunity make it a reliable choice for frequency recognition and control systems.

The LM567 operates as a phase-locked loop system. The internal VCO generates a reference frequency determined by external timing components (a resistor and capacitor). When an input signal at the same frequency is applied, the IC locks onto it and the output pin changes state — typically going low to indicate tone detection.

By adjusting the timing components, the LM567 can be precisely tuned to detect a specific tone or frequency. Its built-in filtering and demodulation circuitry ensure reliable detection even in the presence of noise, making it ideal for communication and control systems.

Click here to view related products

Features:-

• 20 to 1 Frequency Range With an External Resistor
• Logic Compatible Output With 100-mA Current Sinking Capability
• Bandwidth Adjustable From 0 to 14%
• High Rejection of Out of Band Signals and Noise
• Immunity to False Signals
• Highly Stable Center Frequency
• Center Frequency Adjustable from 0.01 Hz to
• 500 kHz