TAS5518C Datasheet, PDF (44/103 Pages) Texas Instruments – 8-Channel Digital Audio PWM Processor

Not Recommended For New Designs
TAS5518C
8-Channel Digital Audio PWM Processor
SLES238A – SEPTEMBER 2008 – REVISED JULY 2009
www.ti.com
After the initialization time, the TAS5518C starts the transition to the operational state with the master
volume set at mute.
Because the TAS5518C has an external crystal time base, following the release of reset, the TAS5518C
sets the MCLK and data rates and performs the initialization sequences. The PWM outputs are held at a
mute state until the master volume is set to a value other than mute via I²C.
3.2.2 Power Down (PDN)
The TAS5518C can be placed into the power-down mode by holding the PDN terminal low. When the
power-down mode is entered, both the PLL and the oscillator are shut down. Volume is immediately set to
full attenuation (there is no ramp down). This control uses the PWM mute sequence that provides a low
click and pop transition to the hard-mute state (M-state).
Power down is an asynchronous operation that does not require MCLK to go into the power-down state.
To initiate the power-up sequence requires MCLK to be operational and the TAS5518C to receive five
MCLKs prior to the release of PDN.
As long as the PDN terminal is held low, the device is in the power-down state with the PWM outputs in a
hard-mute state (M-state). During power down, all I²C and serial data bus operations are ignored.
Table 3-3 shows the device output signals while PDN is active.
Table 3-3. Device Outputs During Power Down
SIGNAL
VALID
PWM P-outputs
PWM M-outputs
SDA
PSVC
SIGNAL STATE
Low
M-state = low
M-state = low
Signal input
M-state = low
Following the application of PDN, the TAS5518C does not perform a quiet shutdown to prevent clicks and
pops produced during the application (the leading edge) of this command. The application of PDN
immediately performs a PWM stop. A quiet stop sequence can be performed by first applying MUTE
before PDN.
When PDN is released, the system goes to the end state specified by the MUTE and BKND_ERR pins
and the I²C register settings.
The crystal time base allows the TAS5518C to determine the CLK rates. Once these rates are
determined, the TAS5518C unmutes the audio.
3.2.3 Back-End Error (BKND_ERR)
Back-end error is used to provide error management for back-end error conditions. Back-end error is a
level-sensitive signal. Back-end error can be initiated by bringing the BKND_ERR terminal low for a
minimum of five MCLK cycles. When BKND_ERR is brought low, the PWM sets either six or eight
channels into the PWM back-end error state. This state is described in Section 2.12. Once the back-end
error sequence is initiated, a delay of 5 ms is performed before the system starts the output re-initialization
sequence. After the initialization time, the TAS5518C begins normal operation. Back-end error does not
affect other PWM modulator operations.
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TAS5518C Controls and Status
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