U4091BM-N Datasheet, PDF (25/38 Pages) ATMEL Corporation – PROGRAMMABLE TELEPHONE AUDIO PROCESSOR

Switch Matrix
U4091BM-N
The switch matrix has 5 inputs and 5 outputs. Every pair of I/Os except AGCO and
AGCIN can be connected. The inputs and outputs used must be enabled. If 2 or more
inputs are switched to an output, the sum of the inputs is available at the output.
The inputs MIC and LRX have offset cancellers with a 3-dB corner frequency of 270 Hz.
AMPB has a 60-kΩ input impedance. The TXO output has a digitally-programmable gain
stage with a gain of 2, 3 to 9 dB depending on AGATX0 (LSB), AGATX1, AGATX2
(MSB) and a first order low-pass filter with 0.5 dB damping at 3300 Hz and 3 dB damp-
ing at 9450 Hz. The outputs RXLS, EPO and AMREC have a gain of 0 dB. The offset at
the outputs of the matrix is less than 30 mV. If a switch is open, the path has a damping
of more than 60 dB.
Figure 19. Switch Matrix Diagram
AGCO AMPB LRX DTMF MIC
Offset
canceller
Offset
canceller
I5 I4 I3 I2 I1
AGC
O5
AGCI
Lowpass
O4 O3 O2 O1
2.9 dB
LTX
AMREC EPO RXLS
AGATX0
AGATX1
AGATX2
TXO
-10 dB
STO
25
4666B–CORD–08/04