TCM320AC46 Datasheet, PDF (4/19 Pages) Texas Instruments – GEBERAL-PURPOSE AUDIO INTERFACE FOR DSP

TCM320AC46
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GENERALĆPURPOSE AUDIO INTERFACE FOR DSP
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SLWS001 − D4091, JUNE 1993
general information
system reliability features
The device should be powered up and initialized as follows:
1. GND is applied.
2. V_CC is applied.
3. All clocks are connected.
4. TTL high is applied to PDN.
5. FSX and/or FSR synchronization pulses are applied.
Even though the device is heavily protected against latch-up, it is still possible to cause it to latch-up under
certain improper power conditions where excess current is forced into or out of one or more terminals. To assure
that latch-up will not occur, it is good design practice to put a reverse-biased Schottky diode between V_CC (power
supply) and GND.
On the transmit channel, digital outputs DOUT and TSX are held in the high-impedance state for approximately
four frames (500 µs) after power up or application of V_CC. After this delay, DOUT, TSX, and signaling are
functional and occur in the proper time slot. The analog circuits on the transmit side require approximately 60
ms to reach their equilibrium value due to the autozero circuit settling time. To further enhance system integrity,
DOUT and TSX are placed in the high-impedance state after an interruption of CLK.
power-down and standby operations
To minimize power consumption, a power-down mode and three standby modes are provided.
For power down, an external low signal is applied to PDN. In the absence of a signal, PDN is internally pulled
up to a high logic level and the device remains active. In the power-down mode, the average power consumption
is reduced to 3 mW.
The standby modes give the user the options of putting the entire device on standby, putting only the transmit
channel on standby, or putting only the receive channel on standby. To place the entire device on standby, both
FSX and FSR are held low. For transmit-only operation, FSX is pulsed and FSR is held low. For receive-only
operation, FSR is pulsed and FSX is held low. In the standby mode with both transmit and receive on standby,
power consumption is reduced to 8 mW. See Table 1 for power-down and standby procedures.
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