 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| Audio ICs Dual preamplifier with ALC BA3308 / BA3308F / BA3308FV The BA3308, BA3308F and BA3308FV are dual preamplifier ICs with built-in ALC circuits, and have been designed for use in stereo radio-cassette recorders and tape recorders. They come in compact 9-pin SIP (BA3308), 14-pin MF (BA3308F) and 14-pin SSOP (BS3308FV) packages, and have two record / playback preamplifiers, and an ALC circuit. The preamplifiers have high gain and low distortion, and can be directly coupled to the tape head without coupling capacitors. This prevents tape head magnetization and "pop" noise generation. A built-in rectifier means that an ALC circuit with good channel balance and large dynamic range can be constructed with addition of just an external time constant circuit. The ICs also include power-on mute circuits that suppress "pop" noise generation. FApplications Stereo radio cassette recorders, cassette decks and home stereo systems and music centers FFeatures 1) Built-in ALC rectifier diode. 2) Wide operating power supply voltage range (VCC = 4.5V to 14V). 3) Low current dissipation (IQ = 3.5mV). 4) High gain (GVO = 80dB). 5) Low distortion (THD = 0.1%). FAbsolute maximum ratings (Ta = 25_C) 6) 7) 8) 9) 10) Low noise (VNIN = 1Vrms) Input coupling capacitors and not necessary. Good ALC channel balance. Power-on mute circuit. ALC dynamic range can be varied by the addition of an external input resistor. FRecommended operating conditions (Ta = 25_C) 193 Audio ICs FBlock diagram BA3308 / BA3308F / BA3308FV FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 7.0V, f = 1kHz and BPF: 20Hz to 20kHz) 194 Audio ICs FMeasurement circuit BA3308 / BA3308F / BA3308FV FApplication example FApplication example circuit PCB (copper side) 195 Audio ICs FTotal application circuit BA3308 / BA3308F / BA3308FV FCircuit operation (1) Recording (1) Recording amplifier (See Fig. 5) The channel 1 and 2 amplifier input stages of the BA3308 (pins 8 and 2) can be direct-coupled, and the input coupling capacitors C1 and C2 are not particularly required. The voltage gain of the recording amplifier is given by GV = R5 / R3, but as a "pop" noise is generated when power is applied, (see "operation notes"), use the time constant circuit values given for C3 and R3 (C4 and R4) in the application example circuit diagram, or values close to these, and adjust the voltage gain with R5 (R6). R5 (R6) is also the DC bias feedback resistor, and is connected between pin 3 (7), and the output capacitor C5 (C6). (2) ALC (See Fig. 6) The BA3308 includes a signal rectifier block and electronic potentiometers required for the ALC. In the signal rectifier block, a comparator compares the DC output voltage component of the output stage signal (pins 3 and 7) to a voltage of 4.5VF (1VF is about 0.7V, so 4.5VF is approximately 3V), and if it is above this, the comparator switches on, and charges the smoothing capacitor C7. The operating point of the amplifier's ch1 and ch2 output stages is fixed at 3VF, so when the signal output voltage is 1.5VF (an effective value of approximately 0.75V), the comparator goes on, DC signals for electronic potentiometer control are generated, and the ALC starts operating. The electronic potentiometers are connected between the input lines (pins 2 and 8) and GND, and the input signals is attenuated by the ratio of the electronic potentiometer resistances and the external resistors R1 and R2. The range of the ALC can be varied by the values of R1 and R2, but if they are too large the S / N ratio will worsen. Sufficient ALC range should be obtained with R1 and R2 values of around several kohms. C7 and R7 connected to pin 5 set the ALC attack and recovery times. The larger the values of these constants, the longer the recovery time, and the smaller the value of C7 the shorter the attack time. 196 Audio ICs (2) Playback (See Fig. 7) During playback, the ch1 and ch2 amplifiers are used as NAB equalizer amplifiers, and time constant circuits are connected between pins 1 and 3, and 7 and 9 in the negative-feedback section to give the NAB characteristics. The voltage gain is given by: GV = R11 ) R9 / (I ) jC9 S R9) / R3 In the same way as for recording, the NAB time constant circuit is adjusted to give the required gain (to prevent BA3308 / BA3308F / BA3308FV generation of a "pop" noise when power is applied). The output stage (pins 3 and 7) operating point is fixed at 3VF. Therefore, as indicated in the VMax. vs, VCC characteristic (see Fig. 19), even if the VCC voltage is made larger than 5V, the maximum output voltage will not exceed 1.2V (typ.). The ALC circuit is not required for playback, so pin 5 is grounded. The S / N ratio during playback is better if the external resistors R1 and R2 that are connected to the input pins (2 and 8) for recording are switched out. 197 Audio ICs BA3308 / BA3308F / BA3308FV FOperation notes The BA3308 has a built-in power-on mute circuit to prevent generation of a "pop" sound when the power is applied. The generation of the "pop" sound is prevented by the DC blocking capacitors C3 and C4 connected to pins 1 and 9, and the charge time required for the ripple filter FApplication board component layout (component side) capacitor C8 that is connected to pin 6. To ensure correct operation of this circuit, use the values given in the application example circuit for C3, C4, R3, R4, C8 and R8. 198 Audio ICs FElectrical characteristics curves BA3308 / BA3308F / BA3308FV 199 Audio ICs BA3308 / BA3308F / BA3308FV FExternal dimensions (Units: mm) 200 |
Price & Availability of BA3308
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |