tfa9879hn NXP Semiconductors, tfa9879hn Datasheet - Page 12

• Manufacturer Part Number: tfa9879hn
• Description: Mono Btl Class-d Audio Amplifier For Portable Applications With Digital Input
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TFA9879_1
Preliminary data sheet
9.2.5.1 Equalizer band function
9.2.5 Equalizer
The de-emphasis filter is a simple first order filter. The cut-off frequency of the
de-emphasis low-pass filter is approximately 3.5 kHz. The TFA9879 de-emphasis filter is
supported for four sample frequencies, as detailed in
Table 6.
[1]
[2]
The equalizer can be used for speaker curve compensation or for customer equalizer
settings, such as jazz, pop, rock or classical music. The equalizer function can be
bypassed or configured as 5-band.
The shape of each parametric equalizer band is determined by the following three filter
parameters:
In the above equation, f
The definition of the quality factor is the center frequency divided by the 3 dB bandwidth
(see
(30 dB).
Each band filter can be programmed to perform a band-suppression (G < 1) or a
band-amplification (G > 1) function around the center frequency.
Each band of the TFA9879 equalizer has a second order Regalia-Mitra all-pass filter
structure. The structure is shown in
Q
[1:0] Control value
01
10
11
00
•
•
•
[2]
=
Value selected via bits DE_PHAS in the De-emphasis, soft/hard mute and power limiter control register
(see
Default value.
(Relative) center frequency
Quality factor Q
Gain factor G
Equation
------------- - ;
f
2
f
–
Table
c
f
1
De-emphasis control
32).
2). In parametric equalizers this is only valid when the gain is set very low
All information provided in this document is subject to legal disclaimers.
f
f
1
2
[1]
:
:
c
Rev. 01 — 8 April 2010
is the center frequency and f
20
20
log
log
10
10







A
------ -
A
------ -
A
A
Mono BTL class-D audio amplifier with digital input
=
f
f
f
f
1
2
c
c
Figure






2 f

c

=
=
6.
f
s
f
de-emphasis inactive
32
44.1
48

3dB f
3dB f
s
(kHz)
,
c
2


Table
s
f
f
1
c
is the sample frequency.
6.
TFA9879
© NXP B.V. 2010. All rights reserved.
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