TSH511_07 Datasheet, PDF (21/25 Pages) STMicroelectronics – Hi-fi stereo/mono infrared receiver and stereo sub-carrier demodulator

TSH511
Figure 29. Squelch schematics
General description
The squelch section is driven by the receiver RX1 but controls both audio buffers.
8.5
Audio buffer sections
The audio signal from an FM demodulator enters into the 6dB/octave low-pass filter for de-
emphasis. 50µs and 75µs are standard de-emphasis values.
After the de-emphasis network, the potentiometer controls the volume.
The rail-to-rail output stage of each audio buffer is able to drive 20mW into 16Ω at 2.3V
supply voltage. Under these conditions, the distortion is typically 0.3% before saturation.
The audio buffers can also drive the other usual impedances used in audio: 32Ω, 600Ω and
10kΩ (see the corresponding distortion curves).
The high input impedances of the audio buffers reduce the coupling capacitors to less than
0.1µF allowing space and cost saving.
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