UTCMC34118 查看數據表（PDF） - Unisonic Technologies

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UTCMC34118

VOICE SWITCHED SPEAKER-PHONE CIRCUIT

Unisonic Technologies 

UTCMC34118 LINEAR INTEGRATED CIRCUIT

POWER SUPPLY, VB, and CHIP DISABLE

The power supply voltage at Vcc( Pin 4) is to be between 3.5 and 6.5 volts. for normal operation, with reduced

operation possible down to 2.8 volts. The output voltage at VB( Pin 15) is ~(Vcc-0.7)/2, and provides the AC ground

for the system. The output impedance at VB is ~400Ω and in conjunction with the external capacitor at VB, forms a

low pass filter for power supply rejection. The choice of capacitor is application dependent based on whether the

circuit is powered by the telephone line or power supply. Since VB biases the microphone and hybrid amplifiers, the

amount of supply rejection at their outputs is directly related to the rejection at VB, as well as their respective gains.

The Chip Disable(Pin 3) permits powering down the IC to conserve power and/or for muting purposes. With CD<0.8

volts., normal operation is in effect. With CD>2 volts. and <Vcc, the IC is powered down. In the powered down mode,

the microphone and the hybrid amplifiers are disabled, and their outputs go to a high impedance state. Additionally,

the bias is removed from the level detectors. The bias is not removed from the filter( Pin 1, 2), the attenuators( Pin 8,

9, 21, 22), or from Pins 13, 14, and 15( the attenuators are disabled, however, and will not pass a signal impedance

at CD is typically 90kΩ, has a threshold of ~1.5 volts., and the voltage at this pin must be kept within the range of

ground and Vcc). If CD is not used, the pin should be grounded.

UTC

UNISONIC TECHNOLOGIES CO., LTD. 12

QW-R108-007,A

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