NXP Semiconductors TFA9812 , , ,

Preliminary data sheet Rev. 02 — 22 January 2009 10 of 66

NXP Semiconductors TFA9812

BTL stereo Class-D audio ampliﬁer with I2S input

•In Soft mute mode the I2S input signal is overruled with a soft mute.

–In Legacy control mode the analog input pin AVOL controls Soft mute mode.

–In I2C control mode I2C control can be used to enable an automatic soft mute

function. See also Section 8.5.3.

•In Hard mute mode the PWM controller is overruled with a 50 % duty cycle square

pulse. The Hard mute mode is only available in I2C control mode.

•In Operating mode the TFA9812 ampliﬁes the I2S audio input signal in line with the

actual control setting.

•In 3-state mode the output stages are switched off.

•Fault mode is entered when a fault condition is detected by one or more of the

protection mechanisms implemented in the TFA9812. In Fault mode the actual device

conﬁguration depends on the fault detected: see Section 8.7 for more information.

Fault mode is for a subset of the faults ﬂagged on the DIAG output pin. When the

DIAG pin is ﬂagged the output stages will be forced to enter 3-state mode. In Sleep

mode the DIAG pin will not ﬂag fault modes.

[1] Clocking faults do not trigger DIAG output.

[2] Under these conditions soft mute still has to be enabled by the appropriate I2C setting.

The I2S interface can be set in master or in slave.

•In I2S master mode the PLL locks to the output signal of the internal crystal oscillator

circuit which uses an external crystal. The BCK, WS and MCLK signals are generated

by the TFA9812. On the MCLK pin the TFA9812 delivers a master clock running at the

crystal frequency.

•In I2S slave mode the PLL can lock to:

–The external MCLK signal on the MCLK pin called MCLK clock mode.

–The I2S input BCK signal on the BCK pin called BCK clock mode.

The I2S master or slave mode can be selected:

•In I2C control mode by selecting the right I2C setting.

•In legacy control mode by selecting the right setting on the SDA/MS pin.

Table 5. Operational mode selection

Pin: DIAG Output Operational mode

selected:

POWERUP ENABLE CSEL AVOL

0 - - - ﬂoating Sleep mode

1 - - - 0 / ﬂoating Fault mode (enabled by

system)[1]

1 1 1 - ﬂoating Soft mute mode (in I2C

control mode)[2]

1 1 0 < 0.8 V ﬂoating Soft mute (in Legacy control

mode)

1 0 - - ﬂoating 3-state mode

1 1 - - ﬂoating Operational mode