TDA1602A application circuit

A1602A adopts dual in-line 40-pin package. Its circuit functions are introduced as follows:
    the playback preamplifier is a low-noise linear amplifier with a voltage gain of 26.4dBoA. Each store card is equipped with an independent playback
preamplifier, which is selected by an electronic switch. Sound Balance Network o
    The high and low-end turning frequencies of the left and right sound playback balance networks are determined by peripheral capacitors.
The time constants 120ys and ∞ of the Fe and Cr02 bands are controlled by logic circuits.
    The high-speed recording head switch is used to connect the compensation capacitor in parallel to the input of the preamplifier during fast recording.
  'The recording and playback head switch allows the B card head to have two working states: recording state and playback state. In the recording state,
the input end of the preamplifier is grounded, and the recording bias current and recording signal are recorded through the magnetic head. In the playback state, the recording bias
end is grounded.
    The high-end and low-end conversion frequencies of the recording equalization network for the left and right channels are determined by peripheral capacitors. By eliminating these capacitors, the recording
equalization network will have a flat response to meet Dolby recording requirements.
    The bias oscillator provides bias and erasure currents for tape recording. The amplitude of the sinusoidal voltage is controlled by the level of pin 15 .
The bias oscillator is automatically turned on only in the recording state.
    The automatic level control range is 20dB, and the change in output voltage is less than 2dBoALC's recovery time and rise time
are adjusted by external components.
    When using a single power supply, the reference voltage provides a potential of 1/2 Vp as the signal ground. When using dual supplies,
the reference voltage is zero potential.
    The internal logic circuit controls the built-in electronic switch through the externally applied DC level. The control signals of pins 8 and 10
are only related to the control level. The control signals of pins 7 and 9 are not only related to the level, but also related to the control level . The rise and fall times
are related to enable smooth transitions of the electronic switch.