TEA1062 Application Note and Pin Voltage

1. Circuit IC introduction TEA1062 is a special telephone integrated circuit produced by Philips. It is a bipolar type. It contains all the circuits and dialing interface circuits required for calling. The minimum operating voltage is 1.6V. The pin arrangement is as follows: 1 pin: positive line pin, the maximum current into this pin should not be greater than 140mA, and the maximum voltage cannot exceed 12V; 2 pin: the gain adjustment pin of the transmission amplifier; 3 pin: the gain adjustment pin of the transmission amplifier; 4 pin : Output pin of the receiving amplifier; pin 5: gain adjusting pin of the receiving amplifier; pin 6: inverting input pin of the sending amplifier; pin 7: non-inverting input pin of the sending amplifier; pin 8: current stabilizer pin; pin 9: negative Line pin; 10 pin: input pin of receiver amplifier; 11 pin: dual tone multi-frequency signal input pin; 12 pin: squelch input terminal; 13 pin: positive power supply decoupling pin; 14 pin: voltage regulator decoupling pin; 15 feet: automatic volume adjustment control input pin; 16 feet: DC resistance adjustment pin.

2. Working principle

1. DC path: R15 is the current limiting resistor, Z3 is the voltage limiting protection diode; the voltage of pin 13 (Vcc) is obtained from the line through the voltage dividing resistor R17, in order to make the voltage of this pin stable and smooth, an external capacity is connected The larger electrolytic capacitor C6 goes to ground. In addition to the voltage supplied to the IC's internal circuit, this pin also supplies power to the electret microphone MIC1.
Summarized as follows: line voltage → IC pin 1 → pin 16 → R30 → ground, the other way is: line voltage → R17 → 13 pin → IC internal power supply and reference circuit → ground 2. Transmission channel: the output of electret MIC1 output The voice signal enters the 7th pin through C9 and R10 and is amplified internally and sent from 1 pin to the line. The output level of the talk amplifier is proportional to the resistance of the resistor R26 between pins 2 and 3.
The role of related components: C9 is a coupling capacitor, adjusting R19 can be adapted to electret microphones with different sensitivities, C7 is an anti-high-frequency interference capacitor, and C13 is used to prevent high-frequency self-excitation.
3. Receiving channel: From the line through R21, C12 into the 10th pin, after internal amplification, from the 4th pin through R22, C11 to the receiver S, after electro-acoustic conversion to restore the sound.
The role of related components: the gain of the receiver amplifier is proportional to the resistance of R20, C12 is the coupling capacitor, C8 anti-interference capacitor, C10 anti-high frequency self-excited capacitor, R22 eliminates the inductive distortion of the receiver.
4. Suppression side sound circuit: composed of R17, R21, R23, R27, R28, R29, R30, C14. Definition of sidetone: When speaking to the microphone, you hear the loud voice of your own speaking in your receiver. Impact: Annoying the speaker and hearing fatigue; forcing the speaker to lower the volume of the speech, thereby affecting the quality of the call.
5. Squelch circuit: Pin 12 is the squelch input pin. When this pin inputs a high level, the sending and receiving channels are disconnected, which plays the role of squelch sending and receiving. When this pin is input low, the sending and receiving channels are connected and normal conversation can be conducted. This pin is controlled by the squelch part of the dialing circuit, but only controls the 12 pin to high level when sending code.
6. Other circuits: The dialing interface circuit of the 11th pin is not used for this machine, and it is directly grounded. The 15th foot is the automatic gain adjustment foot, change the resistance value of the ground resistance R24 under this foot, can adjust the sensitivity difference between sending and receiving in the case of long and short lines.

Three, fault repair

The voltage of each foot of 1062 is as follows:

The above voltage is for reference only. Failure phenomenon: the receiver is not sent and received for maintenance: if the hands-free is normal, please check whether the hook switch CH2-CF2 is in good contact, test the voltage of each pin of the IC to determine whether the voltage regulator Z3 and the IC itself are damaged; otherwise check Squelch circuit (controlled by code sending IC).
Symptom: No transmission maintenance: first check the transmission channel, touch the 7th pin of TEA1062 with tweezers, if the receiver does not click, click C7 or R26 or IC damage; disconnect the transmitter Line, and then touch the pin of C9 with tweezers. If there is no “click, click” sound on the receiver, you should focus on checking whether C9 and R19 are broken. Finally, judge the electret microphone MIC1. The easiest way is to prepare a good one. The microphone is directly soldered to the PCB board with a short wire and blown. If the sound can be heard in the receiver, the original microphone is broken.
Failure phenomenon: small voice transmission for maintenance: the sensitivity of the microphone is reduced due to the influence of moisture and dust; C9 coupling capacitor or gain control resistor R26 deteriorates.
Trouble phenomenon: No call maintenance: touch 5 pins of IC with tweezers, the receiver should have “click” sound, if not, check C8, C10, R20, R22, microphone cord and receiver; then use tweezers to touch IC No. 10 The feet, if there is no "click, click" sound from the receiver, are mostly damaged inside the IC.
Symptom: There is an exchange "buzzing" sound in the receiver. In some cases, the electret microphone MIC1 is unstable inside, which will cause noise to the receiver. This should replace the transmitter; or try to replace the receiver. And a capacitor at the end.