Description
The M-991 is a call progress tone generator integrated circuit for use in telephone systems. The circuit uses low-power CMOS techniques to generate tones which are digitally controlled and highly linear. The M-991 is designed to permit operation with almost any system. The use of integrated circuit techniques allows the M-991 to incorporate the control, tone generating, and power output buffer into a single 14-pin DIP or a 16-pin SOIC. A 3.58-MHz (color burst) crystal-controlled time base guarantees accuracy and repeatability.

Features
• Generates standard call progress tones
• Digital input control
• Linear (analog) output
• Power output capable of driving standard line
• 14-pin DIP and 16-pin SOIC package types
• Single supply 5V CMOS (low power)
• Inexpensive 3.58 MHz time base
• Temperature range from -25ºC to 70ºC (-01 version)
• Temperature range from -40ºC to 85ºC (-02 version)

Applications
• Telephone systems
• Test equipment
• Callback
• Security systems
• Billing systems