MAS9090B Micro Analog Systems, MAS9090B Datasheet - Page 25

• Manufacturer Part Number: MAS9090B
• Description: Low Voltage 14-bit Linear Codec
• Manufacturer: Micro Analog Systems

Bits VS (7) and TE (6) select active input (MIC1,
MIC2 or MIC3). Default is that all inputs are muted.
Transmit (TX) gain can be adjusted from 0 to 22.5
dB in 1.5 dB steps with register CR5 bits (7:4).
Transmit signal after bandpass filter can be fed
back to the receive amplifiers when bit SI (5) is set
high.
Bits OE1 (4) and OE2 (3) select the active output of
the RX gain to be SP1 or SP2. Both outputs can be
muted.
Bit RTE (2) connects the on-chip Ring/Tone
generator to the RX gain input.
Bit HPR (1) provides possibility to bypass high pass
section of the receive bandpass filter.
Bit SE (0) enables the connection of the received
signal to the RX gain input.
TX gain can be programmed from 0 to 22.5 dB in
1.5 dB steps with bits (7:4).
Transmit signal picked after digital bandpass filters
can be fed back to RX gain. Attenuation of the
sidetone signal can be programmed from –12.5 dB
to –27.5 dB in 1 dB steps with bits (7:4). Attenuation
is relative to the input signal level of bandpass filter.
The attenuation of both speaker gains can be
programmed separately from 0 to –30 dB in 2 dB
steps with bits (7:4) and (3:0).
0 dBm0 voltage at the output of the RX gain on pins
SP1/2+ and SP1/2- is 1.965 Vrms when 0 dB gain is
selected.
0 dBm0 level is 61.85 mVrms.
When –30 dB gain is selected the
Output of Tone/Ring generator can be attenuated
from 0 to –27 dB in 3 dB steps with bits (7:4).
Bits f1 (3) and f2 (2) permit selection of f1 and/or f2
frequency generators. When f1 (f2) is selected the
output of the tone generator is signal at the
frequency programmed by the register CR8 (CR9).
If both f1 and f2 are selected the output is a sum of
both signals. In case of squarewave the f1 is
amplitude modulated by f2. In order to meet DTMF
specifications the level of f2 is attenuated by 2 dB
relative to f1.
Bit SN (1) selects the output waveform of the tone
generator to be square (SN=0) or sinewave (SN=1).
Bit DE (0) permits the connection of the tone
generator to the transmit path. Speaker output can
also be provided by using sidetone circuit (bit SI of
CR4) or directly connecting the tone generator to
RX gain with bit RTE of CR4.
March 20, 1998
DA9090B.002
25