TP3070, TP3071, TP3070-X
COMBO? II Programmable PCM CODEC/Filter
General Description
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.