TAS5508C datasheet(52/107 Pages) TI

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TAS5508C

SLES257 – SEPTEMBER 2010

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3.5.1

Manual Bank Selection

The three bank selection bits of the bank control register allow the appropriate bank to be manually

selected (000 = bank 1, 001 = bank 2, 010 = bank 3). In the manual mode, when a write occurs to the

biquad, DRC, or loudness coefficients, the currently selected bank is updated. If audio data is streaming to

the TAS5508C during a manual bank selection, the TAS5508C first performs a mute sequence, then

performs the bank switch, and finally restores the volume using an unmute sequence.

A mute command initiated by the bank-switch mute sequence overrides an unmute command or a volume

command. While a mute is active, the commanded channels are muted. When a channel is unmuted, the

volume level goes to the last commanded volume setting that has been received for that channel.

If MCLK or SCLK is stopped, the TAS5508C performs a bank-switch operation. If the clocks start up once

the manual bank-switch command has been received, the bank-switch operation is performed during the

5-ms, silent-start sequence.

3.5.2

Automatic Bank Selection

To enable automatic bank selection, a value of 3 is written into the bank selection bits of the bank control

data-rate selection registers. The automatic bank selection is performed when a frequency change is

detected according to the following scheme:

1. The system scans bank-1 data-rate associations to see if bank 1 is assigned for that data rate.

2. If bank 1 is assigned, then the bank-1 coefficients are loaded.

3. If bank 1 is not assigned, the system scans bank 2 to see if bank 2 is assigned for that data rate.

4. If bank 2 is assigned, the bank 2 coefficients are loaded.

5. If bank 2 is not assigned, the system loads the bank 3 coefficients.

The default is that all frequencies are enabled for bank 1. This default is expressed as a value of all 1s in

the bank-1 auto-selection byte and all 0s in the bank-2 auto-selection byte.

3.5.2.1

Coefficient Write Operations While Automatic Bank Switch Is Enabled

In automatic mode, if a write occurs to the tone, EQ, DRC, or loudness coefficients, the bank that is

written to is the current bank.

3.5.3

Bank Set

Bank set is used to provide a secure way to update the bank coefficients in both the manual and

automatic switching modes without causing a bank switch to occur. Bank-set mode does not alter the

current bank register mapping. It simply enables any bank coefficients to be updated while inhibiting any

bank switches from taking place. In manual mode, this enables the coefficients to be set without switching

banks. In automatic mode, this prevents a clock error or data rate change from corrupting a bank

coefficient write.

To update the coefficients of a bank, a value of 4, 5, or 6 is written into in the bank selection-bits of the

bank control register. This enables the tone, EQ, DRC, and loudness coefficient values of bank 1, 2, or 3,

respectively, to be updated.

Once the coefficients of the bank have been updated, the bank-selection bits are then returned to the

desired manual or automatic bank-selection mode.

3.5.4

Bank-Switch Timeline

After a bank switch is initiated (manual or automatic), no I2C writes to the TAS5508C should occur before

a minimum of 186 ms. This value is determined by the volume ramp rates for a particular sample rate.

TAS5508C Controls and Status

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