General Description

The HM 9270C/D is a complete DTMF receiver integrating both the bandsplit filter and digital decoder functions. The filter section uses switched capacitor techniques for high- and low-group filters and dial-tone rejection. Digital counting techniques are employed in the decoder to detect and decode all 16 DTMF tone pairs into a 4-bit code. External component count is minimized by on-chip provision of a differential input amplifier, clock-oscillator and latched 3-state bus interface.

Features

• Complete receiver in an 18-pin package.

• Excellent performance.

• CMOS, single 5 volt operation.

• Minimum board area.

• Central office quality.

• Low power consumption.

• Power-Down mode (HM9270D only).

• Inhibit-mode (HM9270D only).