TFA9879 NXP Semiconductors, TFA9879 Datasheet - Page 18

• 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
9.2.10 Dynamic Range Compressor (DRC)
9.2.8 Digital volume control
9.2.9 Zero-crossing volume control
Soft muting prevents audible pops. The function smoothly reduces the gain setting of the
audio channel to the mute level according to a raised cosine shape. Soft muting is
performed in 128 / f
Table 32
The hard mute function immediately switches the outputs to 50 % duty-cycle pulses. As a
result, the input signals are abruptly blocked. Hard mute takes priority over soft mute.
Hard mute is enabled and disabled via bit H_MUTE in
The digital volume control has a range of −70 dB to + 24 dB, programmable in 0.5 dB
steps. The default setting is mute (0 × BD). Attenuation and boosting behavior is affected
by the zero crossing volume setting (see
The volume control settings, and the resulting amplification or suppression factors, are
detailed in
Table 10.
[1]
[2]
The TFA9879 employs zero-crossing volume control to minimize pop noise when the
volume or bass/treble control is changing.
When zero-crossing volume control is enabled (ZR_CRSS = 1; see
TFA9879 increases or decreases the gain only when the audio signal passes a zero
crossing.
The TFA9879 provides a DRC to automatically adjust power levels according to
programmable attack and release levels. The attack level is related to the peak value of
the signal; the release level is related to the RMS value of the signal. The attack level is
programmable using 16 available levels in the range −12 dB to +10 dB. The release level
is programmable using 16 available levels in the range −29 dB to 0 dB relative to the
attack level. The signal level is measured after Equalizer, Bass and Treble processing, but
before it reaches the power limiter.
The DRC can be bypassed via bit DRC_BP in
Control value
00h
01h
..
BBh
BCh
..
FFh
BDh
....
....
Control value is selected via bits VOL in the Volume control register (see
Default value.
[2]
enables and disables the soft mute function.
Table
Volume control amplification and suppression
[1]
All information provided in this document is subject to legal disclaimers.
10.
s
steps. Soft de-mute results in a similar gain increase. Bit S_MUTE in
Rev. 02 — 15 October 2010
Mono BTL class-D audio amplifier with digital input
Section 9.2.9
Gain (dB)
+24
+23.5
steps of 0.5 dB
−69.5
−70
mute
mute
mute
Table
27.
Table
for further details).
32.
Table
31).
Table
TFA9879
© NXP B.V. 2010. All rights reserved.
31), the
18 of 60