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Portable audio I-O interface circuit IC

Published on Oct 28 2010 // Micrcontroller circuits


Portable audio I- O interface circuit IC

Portable information technology (IT) products, input / output (I / O) interface circuit IC as shown in photo.
The circuit is the core of AN2906FJM monolithic IC.
Left / right (L / R) channel playback signals were coupled by the 0.47µF capacitor from the IC {15} {13}
feet feet and enter through the IC internal low-pass filter (LPF), electronic volume (EVR) control circuit,
mixer and speaker amplifier and headphone amplifier circuit, respectively,
from IC {2} {4} feet feet and speaker drive signal output from the {40} {42} feet,
and headphone driver output signal pin.
Microphone signal by the coupling capacitor 0.47µF IC {34} feet from the input to the internal microphone amplifier,
audio signal from the IC {17} pin output.
Vcc supply voltage is applied to the IC {38} feet, the range of 2.7 ~ 5.0V, typical value is 3.3V.
Internal speaker driver IC supply voltage Vcc-sp IC {43} feet from the accession, the scope is 2.7 ~ 5.0V,
typical value is 3.3V. The internal microphone is typically 2V power supply voltage from IC {35} feet available,
{36} feet 1µF capacitor used as a microphone, an external power supply filtering. IC {37} feet of the voltage of Vcc / 2,
is the chip reference voltage. IC {39} pin voltage is Vcc-sp / 2, is the speaker (driver) reference voltage.
  AN2906FJM built-in electronic volume (EVR) and automatic gain control (AGC) on / off (ON / OFF).
When the IC {10} {11} feet feet and input low voltage (0V) when, EVR function cut-off,
whereas if applied high voltage (eg 3.3V) when, EVR control mode takes effect;
IC {22} feet When the voltage is below 0.5V, AGC closed. {22} if put one foot in the high-voltage 2.8 ~ 3.3V,
AGC from control; IC {33} feet low, the microphone amplifier cut-off, when the conduction in the high;
when the IC {32} feet low, HPF opened, and in the high when closed.