WM8983GEFL/RV Wolfson Microelectronics, WM8983GEFL/RV Datasheet - Page 42

• Manufacturer Part Number: WM8983GEFL/RV
• Description: Audio CODECs Mbl Multimedia CODEC w/ 1W Speaker Driver
• Manufacturer: Wolfson Microelectronics

Specifications of WM8983GEFL/RV

• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-32
• Minimum Operating Temperature: - 25 C

WM8983
NOTCH FILTER WORKED EXAMPLE
w
DIGITAL ADC VOLUME CONTROL
The following example illustrates how to calculate the a0 and a1 coefficients for a desired centre
frequency and -3dB bandwidth.
fc = 1000 Hz
fb = 100 Hz
fs = 48000 Hz
1.969995945
NFA0 = -a0 x 213 = -8085 (rounded to nearest whole number)
NFA1 = -a1 x 212 = 8069 (rounded to nearest whole number)
These values are then converted to a 14-bit sign / magnitude notation:
NFA0[13] = 1; NFA0[12:0] = 13’h1F95; NFA0 = 14’h3F95 = 14’b11111110010101
NFA1[13] = 0; NFA1[12:0] = 13’h1F85; NFA1 = 14’h1F85 = 14’b01111110000101
The output of the ADCs can be digitally attenuated over a range from –127dB to 0dB in 0.5dB steps.
The gain for a given eight-bit code X is given by:
0.5 × (G-255) dB for 1 ≤ G ≤ 255;
w
w
a
a
0
1
0
b
=
=
=
=
1
1
−
2
2
π
π
−
+
1 (
f
f
tan(
tan(
b
c
+
/
/
a
f
f
0
s
w
w
s
)
=
=
b
b
cos(
/
/
2
2
) 2
) 2
π
π
w
x (100 / 48000) = 0.01308996939 rads
x (1000 / 48000) = 0.1308996939 rads
=
0
1
1
)
−
+
=
tan(
tan(
−
. 0
. 0
MUTE for G = 0
1 ( +
0130899693
0130899693
. 0
9869949627
/ 9
/ 9
) 2
) 2
)
= 0.9869949627
cos(
PD Rev 4.0 November 2006
. 0
1308996939
Production Data
)
= -
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