80-0206-R Datasheet, PDF (27/49 Pages) List of Unclassifed Manufacturers – Speech Recognition Processor

Data Sheet
RSC-4128
Analog Input
The analog front end (AFE) for the RSC-4128 consists of a preamplifier with gain control, a 16-bit analog-to-digital
converter, digital decimator and channel filters, and associated references. A single analog input can be processed
through the AFE. All of this circuitry can be powered down to conserve battery life by programming register EF.Bit0
to “0”. Setting this bit to “1” powers up the circuitry, requiring a settling time of approximately 10milliseconds.
The analog front end (AFE) performs analog to digital conversions on a low-level signals, which may be derived
from an electret microphone. The microphone signal is amplified by a preamp that provides four levels of gain,
which are selected by programming register D5.Bits[4:3]. Full-scale output for the four settings corresponds to
input signals of 100, 50, 25, and 12.5 millivolts Vpeak-peak, as shown in the table below.
Gain
“sysCtl”
Bits[4:3]
00
01
10
11
Input Referred
Noise
µVrms
5.2*
4.9*
4.6*
4.4
Max Input Signal
mVp-p
mVrms
100
35.4
50
17.7
25
8.8
12.5
4.4
Input signals higher than specified will produce a saturated full scale output with no wrap around. A line level audio
input must be attenuated to the range shown above for use with the AFE.
27
P/N 80-0206-R
© 2006 Sensory Inc.