u4091bm-r ATMEL Corporation, u4091bm-r Datasheet - Page 25

• Manufacturer Part Number: u4091bm-r
• Description: Programmable Telephone Audio Processor
• Manufacturer: ATMEL Corporation

14. Switch Matrix
4872A–CORD–08/05
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 270Hz. AMPB
has a 60-k input impedance. The TXO output has a digitally-programmable gain stage with a
gain of 2 dB to 9 dB (in 1 dB steps) depending on AGATX0 (LSB), AGATX1, AGATX2 (MSB),
and a first order low-pass filter with 0.5 dB damping at 3300Hz and 3 dB damping at 9450Hz.
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 14-1. Switch Matrix Diagram
AGC
AGCO
AGCI
O5
I5
AMREC EPO RXLS
O4
AMPB LRX DTMF MIC
I4
O3
Offset
cancel
I3
O2
I2
LTX
STO
Low pass
O1
2.9 dB
Offset
cancel
I1
-10 dB
AGATX0
AGATX1
AGATX2
TXO
U4091BM-R
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