MT93L04AG Zarlink Semiconductor, MT93L04AG Datasheet - Page 25

• Manufacturer Part Number: MT93L04AG
• Description: Description = 128-Channel Voice Echo CANceller ;; Package Type = Bga ;; No. Of Pins = 365
• Manufacturer: Zarlink Semiconductor

Preliminary Information
MT93L04A
with ECB contains undefined data. Back-to-Back configuration allows a no-glue interface for applications
where bidirectional echo cancellation is required.
Back-to-Back configuration is selected by writing “1” into the BBM bit of both Control Register A1 and Control
Register B1 of a given group of echo cancellers. Table 2 shows the 16 groups of 2 cancellers that can be
configured into Back-to-Back.
Examples of Back-to-Back configuration include positioning one group of echo cancellers between a CODEC
and a transmission device or between two codecs for echo control on analog trunks.
Extended Delay configuration
In this configuration, the two echo cancellers from the same group are internally cascaded into one 128
milliseconds echo canceller. See Figure 5b. This configuration uses only one timeslot on PORT1 and PORT2
and the second timeslot normally associated with ECB contains undefined data.
Extended Delay configuration is selected by writing “1” into the ExtDl bit in Echo Canceller A, Control Register
A1. For a given group, only Echo Canceller A, Control Register A1, has the ExtDl bit. Control Register B1, bit-0
must always be set to zero.
Table 2 shows the 16 groups of 2 cancellers that can each be configured into 64ms or 128ms echo tail
capacity.
Echo Canceller Functional States
Each echo canceller has four functional states: Mute, Bypass, Disable Adaptation and Enable Adaptation.
Mute
In Normal and in Extended Delay configurations, writing a “1” into the MuteR bit replaces Rin with quiet code
which is applied to both the Adaptive Filter and Rout. Writing a “1” into the MuteS bit replaces the Sout PCM
data with quiet code.
25