Datasheet

LargestPositiveNumber:
=0.111 1111 1111 111
=0.999969482421875=1.0 – 1LSB
1
LargestNegativeNumber:
=1.0000 0000 0000 000
=0x8000= –1.0(bydefinition)
1 1 1
1 1 1
S.xxxx xxxx xxxx xxx.. x x x
SignBit
2 Bit
–1
2 Bit
–4
2 Bit
–15
Fraction
Point
1
0 1
15 1
1
N + N z
H(z) =
2 D z
-
-
-
(2)
1 2
0 1 2
15 1 2
1 2
N + 2 × N z + N z
H(z) =
2 2 D z D z
- -
- -
- ´ -
(3)
TLV320ADC3101
www.ti.com ...................................................................................................................................... SLAS553A – NOVEMBER 2008 – REVISED SEPTEMBER 2009
The coefficients of these filters are each 16 bits wide, in 2s-complement format, and occupy two consecutive
8-bit registers in the register space, as shown in Table 7 . Specifically, the filter coefficients are in 1.15 (one dot
15) format with a range from – 1.0 (0x8000) to 0.999969482421875 (0x7FFF), as shown in Figure 43 .
Figure 43. 2s-Complement Coefficient Format
First-Order IIR Section
The transfer function for the first-order IIR filter is given by Equation 2 .
The frequency response for the first-order IIR section with default coefficients is flat at a gain of 0 dB.
Table 7. ADC First-Order IIR Filter Coefficients
Filter FIlter Coefficient ADC Coefficient, Left Channel ADC Coefficient, Right Channel
N0 C4 (page 4 / register 8, 9) C36 (page 4 / register 72, 73)
First-order IIR N1 C5 (page 4 / register 10, 11) C37 (page 4 / register 74, 75)
D1 C6 (page 4 / register 12, 13) C38 (page 4 / register 76, 77)
Biquad Section
The transfer function of each of the biquad filters is given by Equation 3 .
The frequency response for each of the biquad sections with default coefficients is flat at a gain of 0 dB.
Table 8. ADC Biquad Filter Coefficients
Filter FIlter Coefficient ADC Coefficient, Left Channel ADC Coefficient, Right Channel
BIQUAD A N0 C7 (page 4 / register 14, 15) C39 (page 4 / register 78, 79)
N1 C8 (page 4 / register 16, 17) C40 (page 4 / register 80, 81)
N2 C9 (page 4 / register 18, 19) C41 (page 4 / register 82, 83)
D1 C10 (page 4 / register 20, 21) C42 (page 4 / register 84, 85)
D2 C11 (page 4 / register 22, 23) C43 (page 4 / register 86, 87)
BIQUAD B N0 C12 (page 4 / register 24, 25) C44 (page 4 / register 88, 89)
N1 C13 (page 4 / register 26, 27) C45 (page 4 / register 90, 91)
N2 C14 (page 4 / register 28, 29) C46 (page 4 / register 92, 93)
D1 C15 (page 4 / register 30, 31) C47 (page 4 / register 94, 95)
D2 C16 (page 4 / register 32, 33) C48 (page 4 / register 96, 97)
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