AM79C30AVC datasheet(97/101 Pages) AMD

97 / 101 page

Am79C30A/32A Data Sheet

•

The sidetone path defaults to –18-dB attenuation. If

disabling the sidetone path is desired, the sidetone

block must be enabled and programmed for infinite

attentuation.

•

Consider the LIU transformers, series resistors, and

IC LIU output drivers as a functional unit. Transform-

ers that meet CCITT I.430 requirements with other

transceivers are not necessarily appropriate for use

with the DSC circuit, and vice versa.

•

Interrupts should be masked when reading or writ-

ing any indirect or multibyte DSC circuit registers to

prevent the possibility of an interrupt occurring and

destroyed the contents of the Command Register.

•

If the MAP and secondary tone ringer are disabled,

the EAR, AREF, and LS outputs are high-imped-

ance. If the MAP is enabled, the unselected audio

output is high-impedance.

•

The MAP should not be enabled until after the LIU

has achieved synchronization. This will eliminate

the possibility of audible distortion when the internal

device timing is resynchronized to the S Interface.

•

To make optimum use of the MAP digital signal pro-

cessing chain, use digital gain (GX) for fine adjust-

ment, and analog gain (GA) for coarse adjustment.

•

The user must program the Secondary Tone Ringer

Frequency Register (STFR) with a legal value

be-

fore enabling the secondary tone ringer.

•

In order to exit Power-Down Mode due to LIU acti-

vation,

both the F7 interrupt and the DSC/IDC cir-

cuit interrupt pin must be enabled. In order to exit

Power-Down Mode due to IOM-2 activation,

both

the IOM -2 Ti ming Request interrupt and the

DSC/IDC circuit interrupt pin must be enabled.

•

The MAP auto-zero function must be enabled

prior

to enabling the MAP. For all normal applications, the

auto-zero function should always be enabled.

•

To ensure proper operation of the filters (X and R)

and gains (GX, GR, GER, STGR, and ATGR), these

quently than 128-µs intervals. This allows the inter-

nal buffers to the map to operate properly, since

they are updated only once per frame.

AM79C30AVC Datasheet(PDF) 97 Page - Advanced Micro Devices

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