Audio ICs 1.5V / 15mW dual power amplifier BA5152F The BA5152F is a dual-channel power amplifier designed for 1.5V headphone stereos. The circuit consists of a power supply circuit, mute circuit, bias circuit, and two amplifier circuits. To simplify assembly, the gain is fixed, so external negative-feedback components are not required. Applications 1.5V headphone Hi-Fi stereos Features 1) High output. POUT = 15mW (RL = 16Ω). 2) Small “pop” noise. 3) Mute circuit terminal provided. 4) Terminals provided for radiation countermeasures. 5) 6) 7) 8) Good ripple rejection ratio. Few external components required. Good low-voltage characteristics. Built-in power switch circuit. Block diagram Absolute maximum ratings (Ta = 25C) 367 Audio ICs Recommended operating conditions (Ta = 25C) Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 1.5V, f= 1kHz and RL = 16Ω) Measurement circuit 368 BA5152F Audio ICs BA5152F Application example Application board patterns Application board component layout 369 Audio ICs BA5152F Complete application example circuit Circuit description (1) Power supply block The BA5152F has an internal power switch, so the VCC terminal (pin 9) connects directly to the power source. Pin 13 is the power switch, and if it is left open, no bias current flows in the circuit and the IC will not operate. 370 (2) Mute circuit block When pin 13 is connected to VCC, the IC starts up, but the mute circuit operates to suppress a “pop” sound from being generated. The time constant of the power-on mute circuit is determined by the capacitor connected between pins 14 and 15. It is also possible to force the mute circuit to operate by connecting pin 16 to VCC. There is no time constant in this case. Audio ICs (3) Bias block The components connected to pins 2, 3, and 4 set the bias point and VODC. When pin 2 is open circuit, and VCC = 1.25V, the output pin VODC voltage is internally set to 1 / 2VCC. By connecting a resistor to pin 2 and changing the voltage divider ratio, it is possible to vary VODC. Pins 3 and 4 are shorted and connected to earth via an electrolytic capacitor to generate the bias point. When a 33µF component is used, it is possible to obtain 45dB of ripple rejection. This can be improved if pins are independently grounded through capacitors. BA5152F (4) Amplifier block The amplifier circuits have a fixed gain of GV = 21dB. The negative-feedback circuits are on the chip, and the ground point of the negative-feedback circuit uses the bias point as its reference, so connect the input potentiometer to the bias point pins (3 and 4). Connect bypass capacitors to the output pin to prevent oscillation. When the IC is used in sets containing an AM radio, it is possible to reduce unnecessary radiation from the power amplifiers by connecting CR circuits to pins 6 and 11. Electrical characteristics curves (Ta = 25C) 371 Audio ICs External dimensions (Units: mm) 372 BA5152F