Datasheet

Maxim Integrated │ 124
MAX98090 Ultra-Low Power Stereo Audio Codec
www.maximintegrated.com
Figure 26. Dynamic Range Compression and Expansion
Playback Path Dynamic Range Control
The playback path includes a dynamic range control
(DRC) section (Figure 25). The DRC is highly configu-
rable and features digital make-up gain, a dynamic range
compression and expansion, and programmable attack
and release times.
The device dynamic range is determined by the difference
between the full-scale and the RMS noise floor amplitude
of the configured signal path. To avoid performance limit-
ing, the application dynamic range is typically smaller
than the dynamic range of the selected signal path. With
dynamic range control disabled, the input dynamic range
is equal to the output dynamic range (Figure 26). When
compression is enabled, if the input signal amplitude
exceeds the compression threshold the gain is reduced
by the chosen compression ratio. This results in a smaller,
compressed output dynamic range relative to the input
dynamic range. When expansion is enabled, the gain is
decreased by the chosen expansion ratio if the input sig-
nal amplitude instead falls below the expansion threshold.
This results in a larger, expanded output dynamic range.
The DRC also features a digital make-up gain control sec-
tion (Table 54), that can be programmed from 0dB to 12dB
in 1dB increments. To avoid clipping before compression
(during the attack time), the signal cannot at any time
exceed the uncompressed full-scale code. Therefore, the
Figure 27. DRC Enable and Make-Up Gain
INPUT AMPLITUDE (dBFS)
OUTPUT AMPLITUDE (dBFS)
DRC DISABLED
-140 -120 -100 -80 -60 -20-40 0-140-120 -100 -80 -60 -20-40 0-140-120 -100 -80 -60 -20-40 0
FULL SCALE
APPLICATIN OUTPUT
DYNAMIC RANGE
FULL SCALE
DYNAMIC RANGE COMPRESSION DYNAMIC RANGE EXPANSION
FULL SCALE
-140
-120
-100
-80
-60
-40
-20
-140
-120
-100
-80
-60
-40
-20
-140
-120
-100
-80
-60
-40
-20
0
INPUT AMPLITUDE (dBFS)
OUTPUT AMPLITUDE (dBFS)
0
INPUT AMPLITUDE (dBFS)
OUTPUT AMPLITUDE (dBFS)
0
COMPRESSED OUTPUT
DYNAMIC RANGE
EXPANDED OUTPUT
DYNAMIC RANGE
COMPRESSION
THRESHOLD = -30dB
RATIO = 2:1
EXPANSION
THRESHOLD =
-60dB, RATIO = 1:2
APPLICATION INPUT
DYNAMIC RANGE
APPLICATION INPUT
DYNAMIC RANGE
NOISE FLOORNOISE FLOOR NOISE FLOOR
APPLICATION INPUT
DYNAMIC RANGE
0
INPUT AMPLITUDE (dBFS)
OUTPUT AMPLITUDE (dBFS) OUTPUT AMPLITUDE (dBFS)
0
DRC DISABLED
-120
-40
-80
-40-80-120
FULL-SCALE
-20
-60
-100
OUTPUT AMPLITUDE (dBFS)
-20-60-100 0
INPUT AMPLITUDE (dBFS)
-40-80-120 -20-60-100 0
INPUT AMPLITUDE (dBFS)
-40-80-120 -20-60-100
COMPRESSION
THRESHOLD = -30dB
RATIO = 4:1
DRC ENABLED
FULL-SCALE
EXPANSION
THRESHOLD = -60dB
RATIO = 1:2
DRC ENABLED
WITH MAKE-UP GAIN
FULL-SCALE
A
V_DRC
= +10dB
A
V_PLAYBACK
= -10dB
(DV[3:0] = 0xA)
A
V_PLAYBACK
= -10dB (DV[3:0] = 0xA) A
V_PLAYBACK
= -10dB (DV[3:0] = 0xF)A
V_PLAYBACK
= 0dB (DV[3:0] = 0x0)
0
-120
-40
-80
-20
-60
-100
0
-120
-40
-80
-20
-60
-100