TLC32044C, TLC32044E, TLC32044I, TLC32044M, TLC32045C, TLC32045I

VOICE-BAND ANALOG INTERFACE CIRCUITS

SLAS017F − MARCH 1988 − REVISED MAY 1995

13

POST OFFICE BOX 655303

power-up sequence

To ensure proper operation of the AIC and as a safeguard against latch-up, it is recommended that Schottky

to DGTL GND (see Figure 21). In the absence of such diodes, power should be applied in the following

after power up.

AIC responses to improper conditions

The AIC has provisions for responding to improper conditions. These improper conditions and the response of

the AIC to these conditions are presented in Table 1 below.

AIC register constraints

The following constraints are placed on the contents of the AIC registers:

1.

TA register must be

≥ 4 in word mode (WORD/BYTE = high).

2.

TA register must be

≥ 5 in byte mode (WORD/BYTE = low).

3.

TA’ register can be either positive, negative, or zero.

4.

RA register must be

≥ 4 in word mode (WORD/BYTE = high).

5.

RA register must be

≥ 5 in byte mode (WORD/BYTE = low).

6.

RA’ register can be either positive, negative, or zero.

7.

(TA register

± TA’ register) must be > 1.

8.

(RA register

± RA’ register) must be > 1.

9.

TB register must be > 1.

Table 1. AIC Responses to Improper Conditions

IMPROPER CONDITION

AIC RESPONSE

TA register + TA’ register = 0 or 1

TA register − TA’ register = 0 or 1

Reprogram TX counter A with TA register value

TA register + TA’ register < 0

MODULO 64 arithmetic is used to ensure that a positive value is loaded into the TX counter A, i.e., TA

register + TA’ register + 40 hex is loaded into TX counter A.

RA register + RA’ register = 0 or 1

RA register − RA’ register = 0 or 1

Reprogram RX counter A with RA register value

RA register + RA’ register = 0 or 1

MODULO 64 arithmetic is used to ensure that a positive value is loaded into RX counter A, i.e., RA

register + RA’ register + 40 hex is loaded into RX counter A.

TA register = 0 or 1

RA register = 0 or 1

AIC is shut down.

TA register < 4 in word mode

TA register < 5 in byte mode

RA register < 4 in word mode

RA register < 5 in byte mode

The AIC serial port no longer operates.

TB register = 0 or 1

Reprogram TB register with 24 hex

RB register = 0 or 1

Reprogram RB register with 24 hex

AIC and DSP cannot communicate

Hold last DAC output