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| BA3880AS / BA3880AFS Audio ICs High-definition sound processor BA3880AS / BA3880AFS The BA3880AS and BA3880AFS are sound processor ICs that perform phase and harmonic compensation on audio signals to accurately reproduce the "rise" section of audio signals that determines the characteristics of the sound, and thus reproduce the original recording as naturally as possible. !Applications Component stereo systems, radio cassette players, car stereo systems, televisions, VCRs, and active speakers. !Features 1) Correct distortion in the rising section of audio signals that results from miss-matched speakers and amplifiers, and reproduces the original sound faithfully. 2) To allow application with all types of speakers and sources, the clarity can be adjusted using DC control. 3) DC control provided for selection of either processor mode or bypass mode. 4) Bass boost fixed internally to 4dB. !Block diagram BA3880AS BA3880AFS MIXL 1 VCAL 2 + ++ + + HI MID + + + - VCA 22 OUTL GND 1 CTL 24 DETL LO 21 INL DETR 2 CTL 23 VCC 3 HPF 20 APFL DEFR 3 VCA - LO ++ HI MID + + + + + + VCA 22 DEFR DEFL 4 CTL LPF 19 HPFL CTL 4 21 VCC DETL 5 18 LPFL VCAR 5 20 VCAL GND 6 17 BIASC MIXR 6 19 MIXL DETR 7 CTL LPF 16 LPFR OUTR 7 18 OUTL DEFR 8 HPF VCA - ++ 15 HPFR INR 8 + MID LO + + + + 17 INL CTL 9 14 + MID + APFR APFR 9 HPF HI 16 MIXR 11 + ++ + VCAR 10 HI LO 13 INR HPFR 10 LPF 12 OUTR LPFR 11 LPF BIASC 12 - + ++ 15 APFL HPF 14 HPFL 13 LPFL BA3880AS / BA3880AFS Audio ICs !Absolute maximum ratings (Ta = 25C) Parameter Power supply voltage Power dissipation Operating temperature Storage temperature Symbol VCC Pd Topr Tstg Limits 11 1000 -40~+85 -55~+125 Unit V mW C C Reduced by 10mW for each increase in Ta of 1C over 25C. !Recommended operating conditions Parameter Power supply voltage Symbol VCC Limits 5.4~10.8 Unit V !Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 9V, fIN = 1kHz, VIN = 200mVrms, Rg = 600, RL = 100k and VCTL = 4.5V) Parameter Circuit current Voltage gain 1 Voltage gain 2 Voltage gain 3 Voltage gain 4 Voltage gain 5 Channel balance Maximum output voltage Output noise voltage 1 Output noise voltage 2 Total harmonic distortion 1 Total harmonic distortion 2 Channel separation Ripple rejection ratio Symbol Min. 3.9 -2.0 -2.5 -1.0 9.0 - -2.0 2.0 - - - - - 60 Typ. 5.9 0 -0.5 1.0 11.0 4.0 0 2.3 2 16 0.005 0.04 -67 68 Max. 11.8 2.0 1.5 4.0 13.0 - 2.0 - 10 70 0.05 0.4 -60 - Unit mA dB dB dB dB dB dB Vrms Vrms Vrms % % dB dB Conditions ICC GV1 GV2 GV3 GV4 GV5 CB VIN = 0Vrms VCTL = 9V fIN = 10kHz fIN = 10kHz, VCTL = 0V fIN = 50Hz fIN = 10kHz, VCTL = 0V THD = 1% VOM VNO1 VNO2 THD1 THD2 CS RR Rg = 0, DIN AUDIO, VCTL = 9V Rg = 0, DIN AUDIO 400Hz~30kHz BPF, VCTL = 9V 400Hz~30kHz BPF VIN = 1Vrms Rg = 0, fR = 100Hz, VR = 100mVrms Note : When VCTL = 9V, the IC is in bypass mode (through operations). When VCTL = 4.5V, the IC is in processor mode (enhance operations) with minimum definition level. When VCTL = 0V, the IC is in processor mode (enhance operations) with maximum definition level. BA3880AS / BA3880AFS Audio ICs !Measurement circuit BA3880AS 4.7 470p V 1 MIXL OUTL 22 V THD 100k 6800p 2 VCAL INL 21 4.7 A 0.1 9V 47 3 VCC APFL 20 0.01 600 4 1 5 4.7 6 DEFL HPFL 19 DETL LPFL 18 0.068 GND BA3880AS BIASC 17 0.068 47 7 4.7 8 1 9 DETR LPFR 16 DEFR HPFR 15 0.01 4.7 CTL APFR 14 600 10 470p 9V 4.5V 11 VCAR INR 13 MIXR OUTR 12 4.7 6800p V V THD 100k Fig.1 (Units) R : C:F BA3880AS / BA3880AFS Audio ICs BA3880AFS 1 GND DETL 24 4.7 2 4.7 DETR 23 1 3 1 4 DEFR DEFL 22 0.1 47 9V CTL VCC 21 A 5 6800p 9V 4.5V 470p 7 4.7 6 VCAR VCAL 20 6800p MIXR BA3880AFS MIXL 19 470p 4.7 V OUTR OUTL 18 V THD 100k THD 100k V V 8 INR INL 17 4.7 0.01 9 APFR 16 600 10 600 11 0.068 12 47 HPFR APFL 15 0.01 LPFR HPFL 14 BIASC LPFL 13 0.068 Fig.2 (Units) R : C:F BA3880AS / BA3880AFS Audio ICs !Circuit operation The BA3880AS and BA3880AFS high-definition sound processor system ICs treat the amplifiers and speakers as a total audio systems, and perform signal processing at the amplifier input stage to accurately reproduce the rise sections of audio signals that determine the characteristics of sound, and ensure that the replayed audio is as close to the original sound and as natural sounding as possible. Problems relating to playback of sound on audio systems. With naturally-generated sound, high-frequency harmonic components generally occur first, followed by the fundamental frequency components. This also applies to the attack section of the sound that characterizes many musical instruments. It is the amplitude component that gives form to the frequency component and envelope at the rising point of sound, and this expresses the characteristics of the sound. Therefore, when replaying audio on audio playback systems, it is extremely important that the rise section of the signal be expressed accurately with respect to the original sound. However, there is inevitable mismatching between the speakers and amplifiers in current audio systems. Solid-state power amplifiers use negative feedback techniques and operate off a fixed voltage supply, but as speakers are a current element, mismatching in the system inevitably occurs. In addition, the speaker impedance characteristics are strongly influenced by the electrical reactance of the voice coil, and the mechanical reactance of the cone assembly. As a result of this, distortion is generated in the rising sections of audio signals, causing phase shift in the reproduced sound. In addition, impedance increases in the treble region which reduces the speaker amplitude and reduces the harmonic component, and as a result there is a tendency to masking of large mid-frequency signal components that follow, and this makes it difficult to reproduce the rising sections of the sound. !Operating principle To solve the problems described above, the BA3880AS and BA3880AFS perform the audio signal processing described below. Phase shift compensation BASS MIDDLE TREBLE 20 150 2.4k 20k f (Hz) The input signal is separated into three regions: bass (20Hz to 150Hz), middle (150Hz to 2.4kHz) and treble (2.4kHz to 20kHz). These regions are then joined again with the middle and treble regions phase shifted -180 and -360 respectively with respect to the bass signal. This phase shift adjusts the delay time characteristic for each band and minimizes the distortion of the rising section of the audio signal. Amplitude compensation (harmonic compensation) To maintain appropriate auditory balance for the treble region that is made up of harmonic components, a high-speed detector and high-performance VCA circuit are used for amplitude control of the treble component. The amount of compensation is determined from a calculation performed based on the DC level input to the CTL pin, and the DC level detected from the input signal. The internal control signal obtained from this calculation compensates the amplitude of the treble component input to the VCA. This amplitude compensation recovers the harmonic component, and improves the reproduction clarity (definition level) of instruments and vocals. BA3880AS / BA3880AFS Audio ICs Bass boost To maintain good balance with the dynamically changing treble component, the bass component is boosted. The bass boost is fixed at 4dB (typ.) internally, and cannot be adjusted. Mode switch The DC voltage on the CTL pin can be used to switch the IC between processing mode and bypass mode. When processing mode is selected, the audio signal is enhanced using the compensation circuits described above before being output. When bypass mode is selected, the signal bypasses all of the compensation circuits, and only passes through a buffer amplifier before output. External components The frequency characteristic in processing mode with maximum definition level is given below. GAIN C1 C2 LARGE BASS BOOST SMALL LARGE SMALL DEFINITION LEVEL C1: External capacitor connected between the VCA and MIX pins (6800pF in the application circuit). C2: External capacitor connected between the OUT and MIX pins (470pF in the application circuit). FREQUENCY As indicated in the diagram, capacitors C1 and C2 determine the treble component cutoff frequency. By varying the values of these components, the frequency characteristic can be changed as indicated by the dotted line in the diagram. This varies the balance of the harmonic component, and is an important factor in determining the tone quality. Control table Item Threshold level Mode setting Definition level VCC Recommended setting range for bypass mode 0.75 x VCC 0.64 x VCC Min. (1dB Typ.) VCTL 0.57 x VCC 0.5 x VCC Recommended setting range for processor mode 0V (GND) Max. (11dB Typ.) BA3880AS / BA3880AFS Audio ICs !Application example BA3880AS 470p MIXL 1 OUTL 22 L-ch OUTPUT 4.7 68000p VCAL 2 HI + + + + + + - + + LO INL 21 4.7 APFL 20 L-ch INPUT MID VCC VCC 3 VCA 0.1 47 GND 4 1 CTL DETL 5 4.7 GND 6 DEFL HPF HPFL 19 0.01 LPF LPFL 18 0.068 BIASC 17 47 0.068 DETR 7 4.7 DEFR 8 1 CTL VCTL 9 VCA HPF CTL LPF LPFR 16 HPFR 15 0.01 APFR 14 68000p 11 470p + MIXR Fig.3 + + + + 10 HI MID + LO + VCAR - INR 13 4.7 OUTR 12 4.7 R-ch OUTPUT R-ch INPUT (Units) R : C:F + BA3880AS / BA3880AFS Audio ICs BA3880AFS GND DETL 1 DETR 24 4.7 CTL 23 CTL DEFR 1 2 4.7 DEFR 3 1 22 VCA - LO + ++ HI MID + + ++ + VCA VCC 0.1 GND CTL VCTL 47 4 VCAR 21 VCC VCAL 5 6800p 20 MIXL 6800p MIXR 6 R-ch OUTPUT 470p 19 OUTL 470p L-ch OUTPUT OUTR 7 4.7 18 4.7 R-ch INPUT 4.7 INR INL 8 17 4.7 L-ch INPUT 9 0.01 HI HPF LPF MID LO - + 10 LPFR 11 0.068 BIASC 12 47 Fig.4 + HPFR + HPF LPF + + APFR + 16 APFL + + 15 HPFL 0.01 14 LPFL 13 0.068 (Units) R : C:F BA3880AS / BA3880AFS Audio ICs !Operation notes (1) Control pin (CTL) The level of the DC voltage applied to the control pin should be in the range 0V to VCC. Appropriate switching may not be possible in the region of the threshold voltage. Allow sufficient margin when setting this voltage. (2) Recommended operating range Provided the IC is operated within the operating temperature range and within the recommended operating conditions, the general circuit functions are guaranteed to operate correctly, and there will not be significant changes in the electrical characteristics. (3) Application example Provided the circuit constants in the application example circuit are used, the application circuit should function correctly. However, we recommend that you confirm the characteristics of the circuit in actual use, and take note of the cautionary items described above. If you change the circuit constants, check both the static and transient characteristics of the circuit, and allow sufficient margin to accommodate variations in both the IC and the external components. (4) License The ICs are manufactured under license from BBB Sound Inc. (U.S.A.). A license agreement with BBB Sound Inc. is required to use this component. !Electrical characteristic curves 12 10 8 6 4 2 16 DEFINITION LEVEL : (dB) DEFINITION LEVEL : (dB) VCC = 9V f = 10kHz VIN = 200mVrms 14 12 10 8 6 4 2 VCC = 9V f = 10kHz VCTL = 0V 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 CONTROL VOLTAGE : VCTL (V) 0 -10 -20 -30 -40 -50 -60 -70 -80 INPUT VOLTAGE : VIN (dBV) Fig. 3 Definition level vs. control voltage Fig. 4 Definition level vs. input voltage !External dimensions (Units : mm) BA3880AS BA3880AFS 10.00.2 19.40.3 22 12 24 13 0.51Min. 6.50.3 7.80.3 3.40.2 3.950.3 1 11 7.62 5.40.2 1 1.778 0.50.1 0~15 12 1.80.1 0.30.1 0.11 0.8 0.360.1 0.3Min. 0.15 SDIP22 SSOP-A24 0.150.1 |
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