Datasheet

Low-pass
Filter
Digital
modulator
Randomizer
High-pass
filter
Audiointerface
DAC
037-051
TPS65930/TPS65920
www.ti.com SWCS037G–MAY 2008–REVISED APRIL 2011
6.1.4 Digital Audio Filter Module
Figure 6-5 shows the digital audio filter downlink full path characteristics for the audio interface.
Figure 6-5. Digital Audio Filter Downlink Path Characteristics
The HPF can be bypassed. It is controlled by the MISC_SET_2 ARX_HPF_BYP bit set to address 0x49.
Table 6-4 lists the audio filter frequency responses relative to reference gain at 1 kHz.
Table 6-4. Digital Audio Filter RX Electrical Characteristics
Parameter Conditions Min Typ Max Unit
Passband 0.42 F
S
Passband ripple 0 to 0.42F
S
(1)
–0.25 0.1 0.25 dB
Stopband 0.6 F
S
Stopband attenuation F = 0.6F
S
(1)
to 0.8F
S
(1)
60 75 dB
Group delay 15.8/F
S
(1)
μs
Linear phase –1.4 1.4 °
(1) F
S
is the sampling frequency (8, 11.025, 12, 16, 22.05, 24, 32, 44.1, or 48 kHz).
6.1.5 Boost Stage
The boost effect adds emphasis to low frequencies. It compensates for a HPF created by the capacitor
resistor (CR) filter of the headset (in ac-coupling configuration).
There are four modes. Three effects are available, with slightly different frequency responses, and the
fourth setting disables the boost effect:
• Boost effect 1
• Boost effect 2
• Boost effect 3
• Flat equalization: The boost effect is in bypass mode.
NOTE
Boost effect modes are defined in Table 6-5.
Table 6-5 and Table 6-6 include the typical values according to the frequency response versus input
frequency and F
S
frequency.
Copyright © 2008–2011, Texas Instruments Incorporated Audio/Voice Module (TPS65930 Device Only) 59
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