Features
• Full DTMF receiver
• Less than 35mW power consumption
• Industrial temperature range
• Uses quartz crystal or ceramic resonators
• Adjustable acquisition and release times
• 18-pin DIP, 18-pin DIP EIAJ, 18-pin SOIC, 20-pin
PLCC
• CM8870C
— Power down mode
— Inhibit mode
— Buffered OSC3 output (PLCC package only)
• CM8870C is fully compatible with CM8870 for 18-pin
devices by grounding pins 5 and 6

Applications
• PABX
• Central office
• Mobile radio
• Remote control
• Remote data entry
• Call limiting
• Telephone answering systems
• Paging systems

Product Description
The CAMD CM8870/70C provides full DTMF receiver capability by integrating both the bandsplit filter and digital
decoder functions into a single 18-pin DIP, SOIC, or 20-pin PLCC package. The CM8870/70C is manufactured using
state-of-the-art CMOS process technology for low power consumption (35mW, max.) and precise data handling. The
filter section uses a switched capacitor technique for both high and low group filters and dial tone rejection. The
CM8870/70C decoder uses digital counting techniques for the detection and decoding of all 16 DTMF tone pairs into a
4-bit code. This DTMF receiver minimizes external component count by providing an on-chip differential input amplifier,
clock generator, and a latched three-state interface bus. The on-chip clock generator requires only a low cost TV
crystal or ceramic resonator as an external component.