TFA9879 NXP Semiconductors, TFA9879 Datasheet - Page 11

• Manufacturer Part Number: TFA9879
• Description: The TFA9879 contains a processor that supports a range of sound processing featuresincluding a 5-band parametric equalizer, separate bass and treble control, a dynamicrange compressor, soft clip control and volume control
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TFA9879
Product data sheet
9.2.1 Serial interface selection
9.2.2 Mono selection
9.2.3 Programmable high-pass filter
9.2.4 De-emphasis
9.2 Digital Signal Processor (DSP) features
The TFA9879 contains two serial interfaces. The active interface is selected via bit
INPUT_SEL in the Device control register (see
following sequence is initiated:
Mono selection is used to select the digital audio input channel to be amplified. The
options are:
Separate Mono selection is provided for the two serial interfaces via bits MONO_SEL in
the Serial interface control registers (addresses 01h and 03h; see
The TFA9879 features a first-order high-pass filter on the digital audio input to block DC
and low frequency signals. DC values at the output can damage the speaker.
The high-pass filter cut-off frequency is determined by:
The relationship between these parameters and the cut-off frequency is defined in
Equation
HP_CTRL can be programmed to any integer value between 0 and 511 (see
The high-pass filter is bypassed if HP_CTRL = 0 or bit HPF_BP in the Bypass control
register is set to 1 (see
Digital de-emphasis is sometimes needed, especially with older recordings. Emphasis
and de-emphasis originate in the FM transmission, in which the Signal-to-Noise Ratio
(SNR) is not flat over the signal band (in fact the SNR gets worse as the signal frequency
increases). To achieve good SNR over the complete audio band, the high frequency
components of the audio signal were amplified prior to transmission (this is called
Emphasis).
•
•
•
•
•
•
•
•
f
high 3dB
Soft mute is activated for 128/f
The TFA9879 switches to Off mode and the serial interface input is toggled
The TFA9879 switches back to Operating mode and soft mute is released
Left channel
Right channel
Left + right channels (sum divided by two)
The high-pass filter control setting (bits HP_CTRL, see
The sample frequency, f
– (
1:
)
=
f –
--------------------------------------------------------------------- -
All information provided in this document is subject to legal disclaimers.
s
×
ln
Rev. 02 — 15 October 2010
⎛
⎝
4096 HP_CTRL
-------------------------------------------- -
Table
2π
s
–
4096
27).
Mono BTL class-D audio amplifier with digital input
s
seconds
⎞
⎠
Table
21). When this bit is toggled, the
Table
30)
Table
TFA9879
© NXP B.V. 2010. All rights reserved.
22).
Table
11 of 60
30).
(1)