WM8510GEDS/V Wolfson Microelectronics, WM8510GEDS/V Datasheet - Page 21

• Manufacturer Part Number: WM8510GEDS/V
• Description: Audio CODECs VoIP Mono CODEC
• Manufacturer: Wolfson Microelectronics

Specifications of WM8510GEDS/V

• Operating Supply Voltage: - 0.3 V to + 7 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SSOP-28
• Minimum Operating Temperature: - 25 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Production Data
w
PROGRAMMABLE NOTCH FILTER
A programmable notch filter is provided. This filter has a variable centre frequency and bandwidth,
programmable via two coefficients, a0 and a1. These coefficients should be converted to 2’s
complement numbers to determine the register values. a0 and a1 are represented by the register bits
NFA0[13:0] and NFA1[13:0]. Because these coefficient values require four register writes to setup
there is an NFU (Notch Filter Update) flag which should be set only when all four registers are setup.
Table 12 Notch Filter Function
The coefficients are calculated as follows:
Where:
The coefficients are calculated as follows:
These values are then converted to 2’s complement notation to determine the register values.
NOTCH FILTER WORKED EXAMPLE
The following example illustrates how to calculate the a0 and a1 coefficients for a desired centre
frequency and -3dB bandwidth.
NFA0 = -a0 x 2
NFA1 = -a1 x 2
fc = 1000 Hz
R27
Notch Filter 1
R28
Notch Filter 2
R29
Notch Filter 3
R30
Notch Filter 4
REGISTER
ADDRESS
f
a
a
w
w
c
= centre frequency in Hz, f
1
0
0
b
=
=
=
=
13
12
1
1
−
2
2
π
π
1 (
−
+
6:0
7
8
6:0
8
6:0
8
6:0
8
f
f
BIT
tan(
tan(
c
b
+
/
/
a
f
f
0
w
w
s
s
)
NFA0[13:7]
NFEN
NFU
NFA0[6:0]
NFU]
NFA1[13:7]
NFU
NFA1[6:0]
NFU
b
b
cos(
LABEL
/
/
) 2
) 2
w
0
b
)
= -3dB bandwidth in Hz, f
0
0
0
0
0
0
0
0
0
DEFAULT
Notch Filter a0 coefficient, bits [13:7]
Notch filter enable:
0=Disabled
1=Enabled
Notch filter update. The notch filter
values used internally only update when
one of the NFU bits is set high.
Notch Filter a0 coefficient, bits [6:0]
Notch filter update. The notch filter
values used internally only update when
one of the NFU bits is set high.
Notch Filter a1 coefficient, bits [13:7]
Notch filter update. The notch filter
values used internally only update when
one of the NFU bits is set high.
Notch Filter a1 coefficient, bits [6:0]
Notch filter update. The notch filter
values used internally only update when
one of the NFU bits is set high.
s
= sample frequency in Hz
PD, Rev 4.5, September 2008
DESCRIPTION
WM8510
21