Datasheet

TAS5548
www.ti.com SLES270 –NOVEMBER 2012
After the initialization time, the TAS5548 starts the transition to the operational state with the master
volume set at mute.
Because the TAS5548 has an internal oscillator time base, following the release of reset, oscillator trim
command is needed so the TAS5548 can detect the MCLK and data rate and perform 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 I
2
C.
5.2.2 Power Down (PDN)
The TAS5548 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 a non PWM switching mute 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 TAS5548 to receive five
MCLKs prior to the release of PDN.
As long as the PDN pin is held low, the device is in the power-down state with the PWM outputs not
switching. During power down, all I
2
C and serial data bus operations are ignored. Table 5-3 shows the
device output signals while PDN is active.
Table 5-3. Device Outputs During Power Down
SIGNAL SIGNAL STATE
VALID Low
PWM P-outputs Not Switching = Low
PWM M-outputs Not Switching = Low
SDA Inputs Ignored
PSVC Low
Following the application of PDN, the TAS5548 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 I
2
C register settings.
Copyright © 2012, Texas Instruments Incorporated TAS5548 Controls and Status 37
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