Audio ICs Dual preamplifier with ALC detector circuit BA3313L The BA3313L is a dual preamplifier IC with built-in ALC detector circuit, designed for use in stereo radio cassette recorders. It comes in a compact 12-pin ZIP package, and has two record / playback preamplifiers, and an ALC detector circuit. The preamplifiers can be directly coupled to the tape head without coupling capacitors to prevent tape head magnetization and “pop” noise generation. With the built-in ALC detector circuit, an ALC circuit with large dynamic range can be constructed with addition of just an external time constant circuit. Applications Stereo radio cassette recorders Features 1) Input bias circuit does not require coupling capacitors. 2) Built-in ALC circuit with external time constant circuit. 3) Wide operating power supply voltage range. 4) High gain. 5) Low noise. Block diagram 217 Audio ICs FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions (Ta = 25_C) FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 8V and f= 1kHz) 218 BA3313L Audio ICs BA3313L Measurement circuit 219 Audio ICs Application example Operation notes (the resistor marked with an asterisk) Changing the input resistor Rg, and the ALC time constant influences the ALC transient characteristics. In particular, if Rg is less than 3.9kΩ or the time constant capacitor is less than 47µF, the ALC may operate excessively. Do not use smaller values than those recommended for these components. 220 BA3313L Audio ICs BA3313L Electrical characteristics curve External dimensions (Units: mm) 221