The TP3070 and TP3071 are second-generation combined PCM CODEC and Filter devices optimized for digital switching applications on subscriber line and trunk cards. Using advanced switched capacitor techniques, COMBO II combines transmit bandpass and receive lowpass channel filters with a companding PCM encoder and decoder. The devices are A-law and µ-law selectable and employ a conventional serial PCM interface capable of being clocked up to 4.096 MHz. A number of programmable functions may be controlled via a serial control port. Channel gains are programmable over a 25.4 dB range in each direction, and a programmable filter is included to enable Hybrid Balancing to be adjusted to suit a wide range of loop impedance conditions. Both transformer and active SLIC interface circuits with real or complex termination impedances can be balanced by this filter, with cancellation in excess of 30 dB being readily achievable when measured across the passband against standard test termination networks. To enable COMBO II to interface to the SLIC control leads, a number of programmable latches are included; each may be configured as either an input or an output. The TP3070 provides 6 latches and the TP3071 5 latches. See also AN-614, COMBO II application guide.