NT95089

Features:

 Wide operating voltage range: 2.5V - 10V
Optimum use with a constant operating supply voltage (typically 3.5V )
Tone amplitude stability of ±1.5dB within the suggested operating temperature range
 Device power may be derived directly from telephone lines or from small batteries
 Low total harmonic distortion
 TV crystal standard (3.58MHz) is used to derive all frequencies, providing high accuracy and stability
 Specifically designed for electronic telephone applications
 Interfaces directly with a standard push-button telephone keyboard with common terminal
 Dual tone/single tone capability


Pinout




Specifications

Power Supply Voltage (V_DD - V_SS) . . . . -0.3V to +10.5V
Input Voltage (V_IN). . . . . . . . . . . . . -0.3V to V_DD + 0.3V
Maximum Power Dissipation (at 25). . . . . . . . 500mW
Operating Temperature. . . . . . . . . . . . . . -20 to +70
Storage Temperature. . . . . . . . . . . . . . -55 to +150


Description

The NT95089 DTMF generator is specifically designed for applications requiring a fixed supply operating voltage and a high stability tone output, making it ideal for electronic telephone applications. The NT95089 interfaces directly to a standard push-button telephone keyboard (common terminal connected to VSS) and operates directly from telephone lines. All necessary dual-tone frequencies are derived from the widely-used TV crystal standard, providing high accuracy and stability. The required sinusoidal waveform for individual tones is digitally synthesized on the chip, resulting in a waveform with low total harmonic distortion. A voltage reference which is stable over the operating temperature range is generated on the chip; this reference is used to regulate the dual tone frequency levels to ensure that they meet recommended telephone industry specifications.