Datasheet

TAS5548

SLES270 –NOVEMBER 2012

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5.2.3 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 4.1. Once the back-end

error is removed, a delay of 5 ms is performed before the system starts the output re-initialization

sequence. After the initialization time, the TAS5548 begins normal operation. During back-end error I

registers retain current values.

Table 5-4. Device Outputs During Back-End Error

SIGNAL SIGNAL STATE

Valid Low

PWM P-outputs Non PWM Switching = low

PWM M-outputs Non PWM Switching = low

PWM_HP P-outputs Non PWM Switching = low

PWM_HP M-outputs Non PWM Switching = low

SDA Signal input (not driven)

5.2.3.1 BKND_ERR and VALID

The number of channels that are affected by the BKND_ERR signal depends on the setting of bit D1 of

C register 0xE0. If the I

C setting (of bit D1) is 0 (8-channel mode), the TAS5548 places all eight PWM

outputs in the PWM back-end error state. If the I

C setting (of bit D1) is 1, the TAS5548 is in 6-channel

mode. For proper operation in 6-channel mode, the lineout configuration registers (0x09 and 0x0A) must

be 0x00 instead of the default of 0xE0. In this case, VALID is pulled LOW, and the TAS5548 brings PWM

outputs 1, 2, 3, 4, 7, and 8 to a back-end error state, while not affecting lineout channels 5 and 6. Table 5-

4 shows the device output signal states during back-end error.

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