MC34118-D28-T UTC [Unisonic Technologies], MC34118-D28-T Datasheet - Page 11

• Manufacturer Part Number: MC34118-D28-T
• Description: VOICE SWITCHED SPEAKER-PHONE CIRCUIT
• Manufacturer: UTC [Unisonic Technologies]

MC34118
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MICROPHONE AMPLIFIER
non-inverting input internally connected to VB. This amplifier’s open loop gain is typically 80dB when f<100Hz, and
the gain bandwidth is typically 1MHz. Its maximum output swing (p-p) is typically 1 volt. MCI’s input bias current is
typically 40nA out of the pin.
HYBRID AMPLIFIER
telephone line. The first amplifier’s gain is set by external resistor, and the first amplifier’s output drives the second
amplifier (gain of -1).
FILTER
POWER SUPPLY, VB, and CHIP DISABLE
V
CC
Switch to idle quickly,
Switching to idle slowly
is possible 2.8 volts. VB’s output voltage is ~ (Vcc-0.7)/2, and also provides the AC ground.
The current sources are turned off,
The internal 2kΩ resistor is switched in
Discharging the capacitor to VB with a time = 2kΩ x CT.
The current sources are turned off
The switch at the 2kΩ resistor is open
Discharging the capacitor to VB through the external resistor RT with a time=RT x CT.
While the inverting input and the output are pinned out, pins 10/11,the microphone amplifier, has the
At HTO+, HTO-, and HTI, the two hybrid amplifiers provide the two-to-four wire converter for interfacing to the
The external components determined the operation of the filter circuit.
For normal operation the power supply voltage is to be between 3.5v and 6.5v, but with reduced operation the
FUNCTIONAL DESCRIPTION(Cont.)
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
LINEAR INTEGRATED CIRCUIT
QW-R108-007,D
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