Datasheet

3−3
Figure 3−5 shows the derivation of the decimal value of a 48-bit 25.23-format number.
(1 or 0) y 2
23
+ (1 or 0) y 2
22
+ … + (1 or 0) y 2
0
+ (1 or 0) y 2
−1
+ … + (1 or 0) y 2
−23
2
23
Bit 2
22
Bit 2
0
Bit 2
−1
Bit 2
−23
Bit
Figure 3−5. Alignment of 25.23 Coefficient in 32-Bit I
2
C Word
Two 32-bit words must be sent over the I
2
C bus to download a level or threshold coefficient into the TAS3103A. The
alignment of the 48-bit, 25.23-formatted coefficient in the 8-byte (two 32-bit words) I
2
C word is shown in Figure 3−6.
u
Coefficient
Digit 16
u u u u u u u
Coefficient
Digit 15
u u u u
Coefficient
Digit 14
u u u u
Coefficient
Digit 13
S x x x
Coefficient
Digit 12
x x x x
Coefficient
Digit 11
x x x x
Coefficient
Digit 10
x x x x
Coefficient
Digit 9
Word 1
(Most-
Significant
Word)
Integer
Digit 3
Integer
Digit 4
(Bits 2
11
− 2
9
)
Integer
Digit 2
Integer
Digit 1
Sign
Bit
x
Coefficient
Digit 8
x
x x x x x x
Coefficient
Digit 7
x.
x x x
Coefficient
Digit 6
x
x x x
Coefficient
Digit 5
x
x x x
Coefficient
Digit 4
x
x x x
Coefficient
Digit 3
x
x x x
Coefficient
Digit 2
x
x x x
Coefficient
Digit 1
Word 2
(Least-
Significant
Word)
Fraction
Digit 5
Integer
Digit 4
(Bit 2
8
)
0
Fraction
Digit 6
Fraction
Digit 4
Fraction
Digit 3
Fraction
Digit 2
Fraction
Digit 1
Integer
Digit 6
Integer
Digit 5
u = unused or don’t care bits
Digit = hexadecimal digit
Figure 3−6. Alignment of 25.23 Coefficient in Two 32-Bit I
2
C Words