PCT13

The PCT13 cordless telephone base subsystem ICs perform all the audio processing and tone signalling functions required of the base unit in a cordless telephone system.Included on-chip are a preamp for the FM demodulated audio, an output line dirver to the telephone line, a hybrid/preamp for amplifying the telephone incoming signal , and a microphone preamplifier and seperate audio output to a speaker amplifier for providing the intercom function. In addition, a pilot tone detector and security delay timer of PCT13 enables the line connect relay driver in the presence of a pilot tone, a page tone detector allows signalling of the base by the handset for intercom operation, a ring tones oscillator generators the traditional warble tone ofr transmission to handset upon ring detection, and a battery charge sense current detects when the handset is in or out of the base cradle.Finally, on-chip logic with inputs from the detection circuits enables the necessary funtions and directs the signals to the necessary points for proper operation.Use of switched capacitor techniques and crystal controlled divider chains for the detection filters and tone generators not only eliminates many external components , but provides extremly high frequency accuracy without the need for any external circuit trimming.PCT13 has many unique features: the first one is complete audio processing and tone signalling on a single chip. The second one is few external components.The htird one is no trimming required. The forth one is three different pilot tone frequencies available. The fifth one is page and intercom function,etc.

There are some specifications about PCT13. Page detect filter: Center frequency is 875 Hz typ. Tolerance is -3%min and +3% max. Bandwidth is +46 Hztyp. Response time is 100 mS typ. Line output: Impedance is 450 ohm min, 600 ohms typ and 800 ohm max. Gain fron audio inout1 is 2.2 typ. THD1 is 0.8% typ. Microphone input : Impedance is 16 K ohm typ. Signal level is 75 mV.P.max. Audio output: Min.load is 5K ohm min. Max.signal level is 5.5 V.P.max.  

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