BA3575FS

Audio ICs Low-current audio headphone driver BA3575FS The BA3575FS is a headphone driver with an AVC circuit that keeps the output below a fixed level. It features low current consumption, and low output noise, and is ideal for use in portable digital audio equipment. FApplications Portable CD players FFeatures 1) Low current consumption (when VCC = 2.4 V, the quiescent current is 4.9mA). 2) Suitable for use in digital audio equipment (voltage gain: GV = 11.8dB, output noise voltage: VNO = –102dBm typ.). 3) ATT circuit (gain switch). 4) AVC (Auto Volume Control) circuit, for output limiting. 5) Internal standby switch. 6) Internal mute switch. 7) Internal ripple filter. 8) No output coupling capacitor required. 9) Internal beep circuit. 10) SSOP-A20 package. FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions (Ta = 25_C) 871 Audio ICs FBlock diagram BA3575FS 872 Audio ICs FPin descriptions BA3575FS 873 Audio ICs BA3575FS 874 Audio ICs BA3575FS 875 Audio ICs BA3575FS 876 Audio ICs BA3575FS FElectrical characteristics(unless otherwis noted, Ta = 25_C, VCC = 2.4V, RL = 16Ω, f = 1kHz, DIN AUDIO, PWSW = ON, MUTE = OFF, ATT = OFF, and AVC = OFF) 877 Audio ICs FMeasurement circuit BA3575FS 878 Audio ICs FMeasurement circuit switch table (Fig.1) BA3575FS 879 Audio ICs FApplication example BA3575FS 880 Audio ICs BA3575FS FApplication notes (1) “Pop” sound By operating the BA3575FS according to the timing chart shown in Fig.3, it is possible to suppress generation of “pop” noise in the headphone output. (2) Application circuits Provided the recommended circuit constants are used, the application circuits should function correctly. However, we recommend that you confirm the characteristics of the circuits in actual use. If you change the circuit constants, check both the static and transient characteristics of the circuit, and allow sufficient margin to accommodate variations between both ICs and external components. In particular, the capacitors connected to the OUT 1, OUT 2, and VREF pins must have low impedance at high frequency, and have sufficient margin in their temperature characteristics. Also, use an electrolytic or tantalum capacitor for the capacitor connected to the BIASOUT terminal. (3) The PCB pattern for the external components should be designed carefully to prevent oscillation and degradation of the circuit characteristics. Keep the wiring tracks as short as possible, and ensure that there is no impedance between the common connections. The ripple filter pins (1 and 2) and the bias amplifier pins (3 and 4) cannot be used for external power supplies or reference voltages. 881 Audio ICs (4) Recommended operating conditions The curves in Fig.4 below show the maximum allowable power output (PO (Max.) / ch) plotted against the supply voltage (VCC) for different values of ambient temperature (Ta). When VCC y 3.6 V, operate the IC in the region below the dotted line, and do not exceed it. If the maximum allowable power output for each channel (PO (Max.) / ch) is exceeded, the internal power consumption will exceed the power dissipation capacity of the package, and destroy the IC. BA3575FS FElectrical characteristics curves 882 Audio ICs BA3575FS FExternal dimensions (Units: mm) 883