TLC32044C Datasheet, PDF (13/39 Pages) Texas Instruments – VOICE-BAND ANALOG INTERFACE CIRCUITS

TLC32044C, TLC32044E, TLC32044I, TLC32044M, TLC32045C, TLC32045I
VOICE-BAND ANALOG INTERFACE CIRCUITS
SLAS017F – MARCH 1988 – REVISED MAY 1995
power-up sequence
To ensure proper operation of the AIC and as a safeguard against latch-up, it is recommended that Schottky
diodes with forward voltages less than or equal to 0.4 V be connected from V_{CC –} to ANLG GND and from V_{CC –}
to DGTL GND (see Figure 21). In the absence of such diodes, power should be applied in the following
sequence: ANLG GND and DGTL GND, V_{CC –}, then V_{CC +} and V_DD. Also, no input signal should be applied until
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
TA register + TA’ register = 0 or 1
TA register – TA’ register = 0 or 1
TA register + TA’ register < 0
RA register + RA’ register = 0 or 1
RA register – RA’ register = 0 or 1
RA register + RA’ register = 0 or 1
TA register = 0 or 1
RA register = 0 or 1
TA register < 4 in word mode
TA register < 5 in byte mode
RA register < 4 in word mode
RA register < 5 in byte mode
TB register = 0 or 1
RB register = 0 or 1
AIC and DSP cannot communicate
AIC RESPONSE
Reprogram TX counter A with TA register value
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.
Reprogram RX counter A with RA register value
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.
AIC is shut down.
The AIC serial port no longer operates.
Reprogram TB register with 24 hex
Reprogram RB register with 24 hex
Hold last DAC output
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