
Mono ADC
CICFilter
Signal
Processing
Blocks
GPIO1 GPIO2
MISO
SDIN
SCLK
ADC_MOD_CLK
D
IG_M
_IN
IC
D S
-
MONODATA
NODATA
MONODATA
NODATA
MONODATA
NODATA
ADC_MOD_CLK
DIG_MIC_IN
5.5.7
DC Measurement
TSC2117
Low-Power Audio Codec With Embedded miniDSP, Stereo Class-D
Speaker Amplifier, and Smart Four-Wire Touch-Screen Controller
SLAS550A – APRIL 2009 – REVISED JUNE 2009
www.ti.com
Figure 5-17. Digital Microphone in the TSC2117
The TSC2117 outputs internal clock ADC_MOD_CLK on the GPIO1 pin (page 0/register 51, bits D5–D2 =
1010), GPIO2 pin (page 0/register 52, bits D5–D2 = 1010), or MISO pin (page 0/register 55, bits D4–D1 =
0111). This clock can be connected to the external digital microphone device. The single-bit output of the
external digital microphone device can be connected to the GPIO1, GPIO2, SDIN, or SCLK pins (for this
mode, page 0/register 51, 52, 54, or 56 must be configured as a secondary input). Internally, the TSC2117
latches the steady value of the mono ADC data on the rising edge of ADC_MOD_CLK.
Figure 5-18. Timing Diagram for Digital Microphone Interface
When the digital microphone mode is enabled, the analog section of the ADC can be powered down and
bypassed for power efficiency. The AOSR value for the ADC channel must be configured to select the
desired decimation ratio to be achieved, based on the external digital microphone properties.
The TSC2117 supports a highly flexible dc measurement feature using the high-resolution oversampling
and noise-shaping ADC. This mode can be used when the ADC channel is not used for the voice/audio
record function. This mode can be enabled by programming page 0/register 102, bit D7. The converted
data is 24 bits, using the 2.22 numbering format. The value of the converted data for ADC channel can be
read back from page 0/registers 104–106. Before reading back the converted data, page 0/register 103,
bit D6 must be programmed to 1 in order to latch the converted data into the read-back registers. After the
converted data is read back, page 0/register 103, bit D6 must be immediately reset to 0. In
dc-measurement mode, two measurement modes are supported.
Mode A
In dc-measurement mode A, a variable-length averaging filter is used. The length of averaging filter D can
be programmed from 1 to 20 by programming page 0/register 102, bits D4–D0. To choose mode A, page
0/register 102, bit D5 must be programmed to 0.
APPLICATION INFORMATION
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