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<strong>UAC</strong> <strong>357xB</strong><br />
ADVANCE INFORMATION<br />
2.9.2. Microphone Input<br />
The <strong>UAC</strong> <strong>357xB</strong> allows direct connection to electret<br />
microphones and provides the microphone bias voltage<br />
of 3.1 V (2 x1.0 mA max.) on a separate pin, too.<br />
There is a fixed +21.5 dB gain followed by a programmable<br />
gain of 0 dB to +22.5 dB. Table 2–4 shows the<br />
microphone voltage versus gain setting and the input<br />
impedance (depends on gain setting) for full range<br />
ADC input (clipping level).<br />
Mic<br />
L<br />
Line<br />
Mic<br />
R<br />
Line<br />
Preamp<br />
Preamp<br />
Mic-Bias<br />
A<br />
D<br />
A<br />
D<br />
Q-Peak<br />
Mono<br />
Note: For optimum MICBIAS connection, see Fig. 6–2<br />
on page 52.<br />
Fig. 2–9: Analog input configuration<br />
Table 2–4: Microphone input levels<br />
Microphone<br />
Voltage<br />
[mV PP ]<br />
3V Mode<br />
Microphone<br />
Voltage<br />
[mV PP ]<br />
5V Mode<br />
Gain<br />
Setting [dB]<br />
Input<br />
Impedance<br />
[kΩ]<br />
283 377 0 137<br />
238 317 1.5 117<br />
200 267 3 100<br />
168 225 4.5 85<br />
142 189 6 72<br />
119 159 7.5 62<br />
100 134 9 52<br />
84 113 10.5 44<br />
71 95 12 37<br />
60 80 13.5 32<br />
50 67 15 27<br />
42 56 16.5 23<br />
36 47 17 19<br />
30 40 19.5 16<br />
25 34 21 14<br />
21 28 22.5 11<br />
After A/D conversion there is a digital quasi-peak<br />
meter providing level information in APU register.<br />
There is the option to switch the L-signal to both channels<br />
for mono applications. The quasi-peak meterreadout<br />
allows to control level meters or an AGC for<br />
the analog input.<br />
14 Aug. 20, 2004; 6251-650-1AI Micronas
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