MT91L60/61

Data Sheet

6

Zarlink Semiconductor Inc.

Table 1

Transducer Interfaces

Standard handset transducer interfaces are provided by the MT91L60/61. These are:

•

The handset microphone inputs (transmitter), pins M+/M-. The nominal transmit path gain may be adjusted

to either 6.0 dB or 15.3 dB. Control of this gain is provided by the TxINC control bit (Gain Control register 1,

address 00h).

•

The handset speaker outputs (receiver), pins HSPKR+/HSPKR-. This internally compensated fully

differential output driver is capable of driving the load shown in Figure 3. The nominal receive path gain may

be adjusted to either 0 dB, -6 dB or -12 dB. Control of this gain is provided by the RxINC control bit (Gain

Control register 1, address 00h). This gain adjustment is in addition to the programmable gain provided by

the receive filter.

Figure 3 - Audio Gain Partitioning

Code

Sign/

Magnitude

ITU-T (G.711)

µ-Law

A-Law

+ Full Scale

1111 1111

1000 0000

1010 1010

+ Zero

1000 0000

1111 1111

1101 0101

-Zero

(quiet code)

0000 0000

0111 1111

0101 0101

- Full Scale

0111 1111

0000 0000

0010 1010

Serial

Port

Filter/Codec and Transducer Interface

Handset

Receiver

(150

Ω)

PCM

Receive

Filter Gain

0 to -7 dB

(1 dB steps)

Side-tone

-9.96 to

+9. 96 dB

-11 dB

(3.32 dB steps)

-6 dB

Receiver

Driver

-6.0 dB or

0 dB

HSPKR +

HSPKR -

75

Ω

Internal To Device

External To Device

Default Bypass

M+

M

-

Transmit

Gain

6.37 dB

Transmit Gain

-0.37 dB or 8.93 dB

Gain

0 to +7 dB

PCM

Transmitter

Microphone

Transmit Filter

Gain

0 to +7 dB

(1 dB steps)

75

Ω

Decoder

Encoder