TAS3103DBT datasheet(54/146 Pages) TI

54 / 146 page

2−22

CAUTION: Audio data into the TAS3103 is always treated as signed data.

Overhead/Guard Bits

16-Bit

Audio

18-Bit

Audio

20-Bit

Audio

24-Bit

Audio

Precision/Noise Bits

32-Bit

Audio

Figure 2−18. DAP Arithmetic Unit Data Word Structure

The arithmetic engine is a 48-bit (25.23 format) processor consisting of a general-purpose 76-bit arithmetic logic unit

and function-specific arithmetic blocks. Multiply operations (excluding the function-specific arithmetic blocks) always

involve 48-bit DAP words and 28-bit coefficients (usually I2C programmable coefficients). If a group of products are

to be added together, the 76-bit product of each multiplication is applied to a 76-bit adder, where a DSP-like

multiply-accumulate (MAC) operation takes place. Biquad filter computations use the MAC operation to maintain

precision in the intermediate computational stages.

To maximize the linear range of the 76-bit ALU, saturation logic is not used. Intermediate overflows are then permitted

in multiply-accumulate operations, but it is assumed that subsequent terms in the multiply-accumulate computation

flow corrects the overflow condition. The biquad filter structure used in the TAS3103 is the direct form I structure and

has only one accumulation node. With this type of structure, intermediate overflow is allowed as long as the designer

of the filters has assured that the final output is bounded and does not overflow. Figure 2−19 shows a bounded

computation that experiences intermediate overflow condition. 8-bit arithmetic is used for ease of illustration.

The DAP memory banks include a dual port data RAM for storing intermediate results, a coefficient RAM, a 4K x 16

RAM for implementing the delay stages, and a fixed program ROM. Only the coefficient RAM, assessable via the I2C

bus, is available to the user.

8-Bit ALU Operation

(Without Saturation)

10110111

(−73)

−73

+ 11001101

(−51)

+ −51

10000100

(−124)

−124

+ 11010011

(−45)

+ −45

Rollover

01010111

(57)

−169

+ 00111011

(59)

10010010

(−110)

−110

Figure 2−19. DAP ALU Operation With Intermediate Overflow

TAS3103DBT Datasheet(PDF) 54 Page - Texas Instruments

TAS3103DBT Datasheet(HTML) 54 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL