73M1822/73M1922 Data Sheet
DS_1x22_001
1 Introduction
The 73M1922 MicroDAA is a two-device chip set that consists of a 73M1902 Host-Side Device and a
73M1912 Line-Side Device that can be used in any voice-band PSTN telephone interface application
requiring a CODEC. The 73M1822 is a single-package MicroDAA with the same interfaces. Each connects
directly between a host processor and the telephone network with a low-cost pulse transformer to provide
the required high-voltage isolation. A few low-cost components complete the interface to the network. The
pulse transformer transmits encoded digital data rather than analog signals as with other transformer
designs. Data is transmitted and received without the usual degradation from common mode noise and
magnetic coupling typical of other capacitive and voice-band transformer techniques. The data stream
passed between the Host-Side and Line-Side Devices includes the media stream data, control, status and
clocking information.
The data sheet describes both the 73M1922 and 73M1822, which will be collectively referred to as the
73M1x22 in this document.
The Host-Side Device uses a serial data port for transferring transmit and receive data, status and control
information to a host. This interface is compatible with most DSP and high-performance processor
synchronous serial CODEC interfaces.
All media stream data and control information between the Host-Side Device and Line-Side Device of the
73M1822 and 73M1922 are transferred across the pulse transformer. Clocking information used by the
Line-Side Device is embedded in the bit stream received from the Host-Side Device and reconstructed by
the Line-Side Device of the 73M1822 or 73M1922.
On start up, the Host-Side Device provides power to the Line-Side Device through the transformer. After
going off-hook, the Line-Side Device is capable of being powered from the PSTN network. The only
physical connections between the devices are the primary side of the pulse transformer that is connected to
the Host-Side Device and the secondary side to the Line-Side Device.
Figure 1 shows a reference block diagram of the 73M1922 connected by a pulse transformer and example
external line interface circuitry shown for clarification.
Host-Side Device
73M1902
Line-Side Device
73M1912
CTL
STA
Ring
Buffer
Aux A/D
STA
Tip
Digital
Sigma
Delta
Modulator
(DSDM)
PRP
SCP
TxA
Transmit
Analog
Front End
(TxAFE)
TBS
Transmit
Interpolation
Filter (TIF)
TxData
RxData
Off-Chip
Line
Interface
Circuit
On-Chip
Line
Interface
Circuit
Modem
Line
Side
Barrier
Interface
(LSBI)
TxD
RxD
Side
Barrier
Interface
(MSBI)
MAFE
Interface
Receive
Decimation
Filter (RDF)
Receive
Analog
Front End
(RxAFE)
SinC3
Filter
RBS
RxA
PRM
SCM
Ring
Figure 1: Simple 73M1x22 Reference Block Diagram
The Host-Side Device (73M1902) consists of:
1. Modem Analog Front End (MAFE) Interface Block
2. Transmit Interpolation Filter (TIF)
3. Receive Decimation Filter (RDF)
4. Modem-Side Barrier Interface Circuit (MSBI)
6
Rev. 1.6
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
