TCM320AC36, TCM320AC37

VOICE-BAND AUDIO PROCESSORS (VBAP

™)

SLWS003C – MAY 1992 – REVISED APRIL – 1998

17

POST OFFICE BOX 655303

PRINCIPLES OF OPERATION

_

+

_

+

IN

VMID

4

2

3

EARGS

EARA

EARB

+

–

NOTE A: Terminal numbers shown are for the DW and N packages.

Figure 6. Earphone Audio-Output Amplifier Configuration and Internal Gain-Setting Network

receive data format

In the companded mode, eight bits of data are received. The sign bit is the first bit received (see Table 2).

In the linear mode, 16 bits of data are received. The first 13 bits are the D/A code, and the remaining three bits

form the volume control word (see Table 2). The volume control function is actually an attenuation control in

which the first bit received is the most significant. The maximum volume occurs when all three volume control

bits are zero. Eight levels of attenuation are selectable in 3-dB steps, giving a maximum attenuation of 21 dB

when all bits are 1s. The volume control bits are not latched into the VBAP and must be present in each received

data word.