PSB21473FV13XT Infineon Technologies, PSB21473FV13XT Datasheet - Page 387

• Manufacturer Part Number: PSB21473FV13XT
• Manufacturer: Infineon Technologies

Specifications of PSB21473FV13XT

• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (min): 3.135V
• Operating Supply Voltage (max): 3.6V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 144
• Lead Free Status / RoHS Status: Compliant

smooth system noise below is neglected. It should be the level of the minimum system
noise which is always existing; in the transmit path the noise generated by the telephone
circuitry itself and in receive direction the level of the first bit which is stable without any
speech signal at the receive path. Table 20-7 shows the parameters for the speech
detector.
Table 20-7
Parameter # of bytes Range
LIM
OFF
PDS
PDN
LP1
LP2S
LP2N
LP2L
The input signal of the speech detector can be connected to either the input signal of the
echo suppression unit (as shown for SDX in Figure 20-10) or the output of the
associated AGC (as shown for SDR in Figure 20-10).
20.1.3.2 Speech Comparators (SC)
The echo suppression unit has two identical speech comparators (SCAS, SCLS). Each
comparator can be programmed individually to accommodate the different system
characteristics of the acoustic interface and the line interface. As SCAS and SCLS are
identical, the following description holds for both SCAS and SCLS.
The SC has two input signals SX and SR, which map to microphone/loudspeaker for
SCAS and line in/line out for SCLS.
The speech comparator decides whether the signal coming in on SR is only an echo from
the signal outgoing on SX or a real speech activity. The result is then interpreted by the
Attenuation Control of figure 20-11. In general, the SC works according to the following
equation:
Therefore, SCAS controls the switching to transmit state and SCLS controls the
switching to receive state. Switching is done only if SX exceeds SR by at least the
Data Sheet
1
1
1
1
1
1
1
1
Speech Detector Parameters
0 to -95 dB
0 to 95 dB
1 to 2000 ms
1 to 2000 ms
1 to 2000 ms
2 to 250 s
1 to 2000 ms
0 to 95 dB
if
SX > SR + V then switch state
387
Comment
Limitation of log. amplifier
Level offset up to detected noise
Peak decrement PD (speech)
Peak decrement PD (noise)
Time constant LP1
Time constant LP2 (speech)
Time constant LP2 (noise)
Maximum value of LP2
Digital Signal Processor
PSB 21473
2003-03-31
INCA-D