BA3570FS

Audio ICs ALS headphone driver BA3570F / BA3570FS The BA3570F and BA3570FS are stereo headphone amplifiers with ALS (Auto Loudness System) which have been designed for use as headphone drivers in audio equipment. FApplications Stereo headphones FFeatures 1) The use of ALS (Auto Loudness System) makes it possible to obtain a dynamic sound regardless of the volume level. 2) Built-in power mute circuit. 3) Built-in bypass circuit. FBlock diagram 554 Audio ICs FPin descriptions (pin numbers are for 22-pin BA3570F) BA3570F / BA3570FS FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions (Ta = 25_C) 555 Audio ICs BA3570F / BA3570FS FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 3.0V, RL = 16Ω, f = 1kHz, and the measurement circuit is as shown in Fig. 1) 556 Audio ICs FMeasurement circuit BA3570F / BA3570FS FExplanation of ALS operation and attached components (pin numbers are for 22-pin BA3570F) (1) ALS ON When ALS is on, the signal circuit (including external connections) is as shown in Fig. 2. 557 Audio ICs 1) Bass signal transmission and gain vs. frequency BA3570F / BA3570FS 2) Treble signal transmission and gain vs. frequency The gain and cutoff frequency of each block is as follows: 1 LPF1 cutoff frequency : fCL1= (Hz) 2π S (R3//R4) S C4 Amp E gain : GV(E) = 20log R15+R16 R15 (dB) z15dB Amp A gain ATT attenuation Amp B gain Amp B cutoff frequency : GV(A) = 0 : GV(ATT) = 20log : GV(B) = 20log : fCL3 = 1 2π S ...