
5.6 Audio DAC and Audio Analog Outputs
5.6.1
DAC
TSC2117
Low-Power Audio Codec With Embedded miniDSP, Stereo Class-D
Speaker Amplifier, and Smart Four-Wire Touch-Screen Controller
www.ti.com
SLAS550A – APRIL 2009 – REVISED JUNE 2009
Mode B
To choose mode B, page 0/register 102, bit D5 must be programmed to 1. In dc-measurement mode B, a
first-order IIR filter is used. The coefficients of this filter are determined by D, page 0/register 102, bits
D4–D0. The nature of the filter is given in
Table 5-23.Table 5-23. DC Measurement Bandwidth Settings
D:Page 0/Register 102, Bits D4–D0
–3 dB BW (kHz)
–0.5 dB BW (kHz)
1
688.44
236.5
2
275.97
96.334
3
127.4
44.579
4
61.505
21.532
5
30.248
10.59
6
15.004
5.253
7
7.472
2.616
8
3.729
1.305
9
1.862
652
10
931
326
11
465
163
12
232.6
81.5
13
116.3
40.7
14
58.1
20.3
15
29.1
10.2
16
14.54
5.09
17
7.25
2.54
18
3.63
1.27
19
1.8
0.635
20
0.908
0.3165
By programming page 0/register 103, bit D5 to 1, the averaging filter is periodically reset after 2R number
of ADC_MOD_CLK periods, where R is programmed in page 0/register 103, bits D4–D0. When
page 0/register 103, bit D5 is set to 1, then the value of D should be less than the value of R. When
page 0/register 103, bit D5 is programmed to 0, the averaging filter is never reset.
Each channel of the stereo audio DAC consists of a digital audio processing block, a digital interpolation
filter, a digital delta-sigma modulator, and an analog reconstruction filter. This high oversampling ratio
(normally DOSR is between 32 and 128) exhibits good dynamic range by ensuring that the quantization
noise generated within the delta-sigma modulator stays outside of the audio frequency band. Audio analog
outputs include stereo headphone/lineouts and stereo class-D speaker outputs.
The TSC2117 stereo audio DAC supports data rates from 8 kHz to 192 kHz. Each channel of the stereo
audio DAC consists of a signal-processing engine with fixed processing blocks, a programmable miniDSP,
a digital interpolation filter, multibit digital delta-sigma modulator, and an analog reconstruction filter. The
DAC is designed to provide enhanced performance at low sampling rates through increased oversampling
and image filtering, thereby keeping quantization noise generated within the delta-sigma modulator and
signal images strongly suppressed within the audio band to beyond 20 kHz. To handle multiple input rates
and optimize power dissipation and performance, the TSC2117 allows the system designer to program the
oversampling rates over a wide range from 1 to 1024 by configuring page 0/registers 13 and 14. The
system designer can choose higher oversampling ratios for lower input data rates and lower oversampling
ratios for higher input data rates.
APPLICATION INFORMATION
43