Datasheet

TLV320AIC1110
SLAS359 – DECEMBER 2001
7
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detailed description (continued)
analog modulator
The transmit channel modulator is a third-order sigma-delta design.
transmit filter and PGA
The transmit filter is a digital filter designed to meet CCITT G.714 requirements. The device operates either in
the 15-bit linear or 8-bit companded µ-law or in the A-law mode, which is selectable through the I
2
C interface.
The transmit PGA defaults to 0 dB.
sidetone
A portion of the transmitted audio is attenuated and fed back to the receive channel through the sidetone path.
The sidetone path defaults to the mute condition. The default gain of -12 dB is set in the sidetone control register.
The sidetone path can be enabled by writing to the power control register.
receive volume control
The receive volume control block acts as an attenuator with a range of –18 dB to 0 dB in 2-dB steps for control
of the receive channel volume. The receive volume control gain defaults to 0 dB.
receive filter and PGA
The receive filter is a digital filter that meets CCITT G.714 requirements with a high-pass filter that is selectable
through the I
2
C interface. The device operates either in the 15-bit linear or the 8-bit µ-law or the A-law
companded mode, which is selectable through the I
2
C interface. The gain defaults to –4 dB, representing a
3-dBm level for a 32-Ω
load impedance and the corresponding digital full scale PCMI code.
digital modulator and filter
The second-order digital modulator and filter convert the received digital PCM data to the analog output required
by the earphone interface.
earphone amplifiers
The analog signal can be routed to either of two earphone amplifiers, one with differential output (EAR1ON and
EAR1OP) and one with single-ended output (EAR2O). Clicks and pops are suppressed for EAR1 differential
output only.
tone generator
The tone generator provides generation of standard DTMF tones which are output to (1) the buzzer driver, as
a PDM signal, (2) the receive path DAC for outputting through the earphone, or (3) as PCMO data. The integer
value is loaded into one of two 8-bit registers, the high-tone register (04), or the low-tone register (05) (see the
Register Map Addressing section). The tone output is 2 dB higher when applied to the high tone register (04).
The high DTMF tones must be applied to the high-tone register, and the low DTMF tones to the low-tone register.
The tone signals can be generated with three different resolutions at ∆F= 7.8125 Hz, 15.625 Hz, and 31.250 Hz.
The resolution option can be selected by setting the register (06).
analog mux
The analog switch can be used to source an analog signal to two different loads. The output can be reselected
by setting the auxiliary register (06).