Datasheet

(1or0) 2 +´
1
(1or0) 2 +(1or0) 2 +.......(1or0) 2 +.......(1or0) 2´ ´ ´ ´
0 –1 –4 –23
2 Bit
1
2 Bit
0
2 Bit
–1
2 Bit
–4
2 Bit
–23
M0126-01
u
Coefficient
Digit8
u
u u u u
S
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
Fraction
Digit5
Fraction
Digit4
Fraction
Digit3
Fraction
Digit2
Fraction
Digit1
Integer
Digit1
Sign
Bit
Fraction
Digit6
u=unusedordon’tcarebits
Digit=hexadecimaldigit
M0127-01
0
TAS5710
www.ti.com ............................................................................................................................................................................................... SLOS605 – JANUARY 2009
The decimal value of a 3.23 format number can be found by following the weighting shown in Figure 35 . If the
most significant bit is logic 0, the number is a positive number, and the weighting shown yields the correct
number. If the most significant bit is a logic 1, then the number is a negative number. In this case every bit must
be inverted, a 1 added to the result, and then the weighting shown in Figure 36 applied to obtain the magnitude
of the negative number.
Figure 36. Conversion Weighting Factors — 3.23 Format to Floating Point
Gain coefficients, entered via the I2C bus, must be entered as 32-bit binary numbers. The format of the 32-bit
number (4-byte or 8-digit hexadecimal number) is shown in Figure 37
Figure 37. Alignment of 3.23 Coefficient in 32-Bit I2C Word
Sample calculation for 3.23 format
db Linear Decimal Hex (3.23 Format)
0 1 8388608 00800000
5 1.7782794 14917288 00E39EA8
-5 0.5623413 4717260 0047FACC
X L = 10
(X/20)
D = 8388608 × L H = dec2hex (D, 8)
Sample calculation for 9.17 format
db Linear Decimal Hex (9.17 Format)
0 1 131072 00020000
5 1.7782794 233082.6 00038E7A
-5 0.5623413 73707.2 00011FEB
X L = 10
(X/20)
D = 131072 × L H = dec2hex (D, 8)
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