TP3069``Enhanced'' Serial Interface CMOS CODEC/Filter COMBOÉ General Description The TP3069 (A-law) is a monolithic PCM CODEC/Filter utilizing the A/D and D/A conversion architecture shown in Figure 1 , and a serial PCM interface. The device is fabricated using National's advanced double-poly CMOS process (microCMOS). Similar to the TP305X family, this device features an additional Receive Power Amplifier to provide push-pull balanced output drive capability. The receive gain can be adjusted by means of two external resistors for an output level of up to g6.6V across a balanced 600X load. Also included is an Analog Loopback switch and a TSX output. Note: See also AN-370, ``Techniques for Designing with CODEC/Filter COMBO Circuits.''