TAS5706APAP datasheet(36/71 Pages) TI1

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BANK SWITCHING

TAS5706A

TAS5706B

SLOS606D – MARCH 2009 – REVISED SEPTEMBER 2009............................................................................................................................................. www.ti.com

The TAS5706A uses an approach called bank switching together with automatic sample-rate detection. All

processing features that must be changed for different sample rates are stored internally in the TAS5706A. The

TAS5706A has three full banks storing information, one for 32 kHz, one for 44.1/48 kHz, and one for all other

data rates. Combined with the clock-rate autodetection feature, bank switching allows the TAS5706A to detect

automatically a change in the input sample rate and switch to the appropriate bank without any MCU

intervention.

The TAS5706A supports three banks of coefficients to be updated during the initialization. One bank is for 32

kHz , a second bank is for 44.1/48 kHz, and a third bank is for all other sample rates. An external controller

updates the three banks (see the I2C register mapping table for bankable locations) during the initialization

sequence.

If the autobank switch is enabled (register 0x50, bits 2:0) , then the TAS5706A automatically swaps the

coefficients for subsequent sample rate changes, avoiding the need for any external controller intervention for a

sample rate change.

By default, bits 2:0 have the value 000; that means the bank switch is disabled. In that state, any update to

locations 0x29–0x3F go into the DAP. A write to register 0x50 with bits 2:0 being 001, 010, or 011 brings the

system into the coefficient-bank-update state update bank1, update bank2, or update bank3, respectively. Any

subsequent write to locations 0x29-0x3F updates the coefficient banks stored outside the DAP. After updating all

the three banks, the system controller should issue a write to register 0x50 with bits 2:0 being 100; this changes

the system state to automatic bank update. In automatic bank update, the TAS5706A automatically swaps banks

based on the sample rate.

In the headphone mode, speaker equalization and DRC are disabled, and they are restored upon returning to the

speaker mode.

Command sequences for initialization can be summarized as follows:

Enable factory trim for internal oscillator: Write to register 0x1B with a value 0x00.

Update coefficients: Coefficients can be loaded into DAP RAM using the manual bank mode.

Use automatic bank mode.

Enable bank-1 mode: Write to register 0x50 with 0x01. Load the 32-kHz coefficients. TI ALE

can generate coefficients.

Enable bank-2 mode: Write to register 0x50 with 0x02. Load the 48-kHz coefficients.

Enable bank-3 mode: Write to register 0x50 with 0x03. Load the other coefficients.

Enable automatic bank switching by writing to register 0x50 with 0x04.

Bring the system out of all-channel shutdown: Write 0 to bit 6 of register 0x05.

Issue master volume: Write to register 0x07 with the volume value (0 db = 0x30).

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Product Folder Link(s): TAS5706A TAS5706B

TAS5706A is Not Recommended for New Designs

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