The BA3308F /FV is a dual preamplifier for recording and playback ALC (Automatic Level Control), specially developed for stereo radios, recorders, recorders and other preamplifier audio applications. ALC circuit has built-in rectifier circuit with wide adjustable dynamic range, high gain, low distortion amplifier direct coupling and mute circuit to cut off popping sound when power is applied. Available in SOP14 or SSOP-B14 packages.

Features

1) Built-in ALC rectifier diode

2) Wide operating power supply voltage range (VCC = 4.5~14 V)

3) Low current consumption (IQ = 3.5mA)

4) High gain (GVO = 80dB)

5) Low distortion (THD = 0.1%)

6) Low noise (VNIN = 1μVrms)

7) No need for input coupling capacitors

8) Good ALC channel balance

9) Built-in power mute circuit

10) The dynamic range of the ALC can be changed by additional input resistance.

application

Stereo Radio, Cassette Recorder, Stereo Cassette Recorder, Home Stereo, Music Center, etc.

Absolute Maximum Ratings (Ta = 25°C)

1 4.5 mW/°C derating at 25°C when mounted on a 70mm x 70mm x 1.6mm PCB board.

2 Reduced by 3.5 mW/°C at 25°C

Electrical Characteristics (Unless otherwise stated, Ta=25℃, Vcc=7.0V, f=1kHz, BPF20~20kHz)

block diagram

record recording amplifier

The BA3308F/FV amplifiers (13pin, 9pin) of the ch1 and ch2 input stages can be directly coupled or use coupling capacitors (C1/C2). The voltage gain of the recording amplifier is determined by GV = R5/R3. The R5/R6 and C3/R3 regulator controls the popping sound at power-up (see "Usage Precautions") and the feedback DC bias by setting the output stage to R5/R6 and C5/C6.

The BA3308F/FV has the required volume for on-chip signal rectifiers and electronic components ALC. The signal rectifier compares the direct current output voltage superimposed on the output stage (1,7pin) signal to the reference voltage 4.5VF (≒3V; 1VF is about 0.7V) In the comparator circuit, if the output voltage is higher, it is necessary to connect the comparator to Pass to charge the smoothing capacitor C7. Since the operation of the output stages of amplifiers ch1 and ch2 is fixed at 3VF, the output voltage of the comparator turn-on signal at peak is 1.5VF (effective value is about 0.75V). Once the ALC controls the electronic volume of the DC signal operation begins. Electronic volume, connected between the input line (13, 9pin) and GND, the resistance value of the input signal to attenuate the electronic volume according to the ratio of the external resistance (R1, R2). The ALC range varies according to the values of R1 and R2. For small ALC variants S/N will be determined by applying R1 and R2 of a few kΩ to obtain sufficient ALC range. Attack time and recovery time ALC are set according to C7 and R7 of 4pin. If the time constant (C7, R7) is large, the recovery time is long, and if C7 becomes smaller, the attack time will be shorter.

Since amplifiers ch1 and ch2 are used as NAB equalizers. When playing the amplifier, the NF part (1-11pin, 7-10pin) of the time constant circuit is established to obtain the NAB characteristic. The voltage gain at this time is determined by the following formula: GV = │ R11 + R9 / (│+jωC9 · R9 ) │ / R3 Obtain the necessary gain by adjusting (boot-up pop-up noise prevention) NAB time constant circuit in the same way The point of operating the output stage (1,7pin) is fixed at 3VF when adjusting the gain during the recording phase. Therefore, even if VCC is raised to 5V or higher, as in the VMAX-VCC characteristic (Figure 13), the maximum output voltage does not exceed 1.2V (typ.). 4pin is grounded during playback because ALC is not required. For better SNR characteristics during playback, do not use R1 and R2 to connect to input pins (13pin, 9pin).

Measurement circuit

Application circuit

Precautions for use

1) The figures and data in the entry are representative design values and are not guaranteed values for the project.

2) While ROHM is confident that the example application circuit reflects the best recommendations, be sure to verify the circuit characteristics for your specific application. Modifying other externally connected constant circuits may cause changes in external components as well as the static and transient characteristics of the Rohm to allow sufficient margin in determining circuit constants.

3) Absolute Maximum Ratings

Using the IC beyond its absolute maximum ratings, such as the applied voltage or operating temperature range (Topr), may cause damage to the IC. No assumptions should be made about the state of the IC (short mode or open mode mode) when suffering this damage. Physical safety measures should be implemented during use, such as fuse ICs may exceed absolute maximum ratings.

4) GND potential

Ensure minimum GND pin potential under all operating conditions. Make sure no pins are below voltage GND at any time, whether it's a transient signal or not.

5) Thermal Design

Thermal design is performed by considering the allowable dissipation (Pd), where there is sufficient margin to actually use the state.

6) Short circuit between terminals and wrong installation

Pay attention to the mounting direction of the IC. Mounting orientation between terminals, GND, or other terminals, or short-circuiting components on the wrong circuit can damage the IC.

7) Operate in strong magnetic field

Using the IC in strong electromagnetic fields can cause malfunctions in operation.

8) The BA3308F/FV has an on-chip power mute circuit to check for popping sound at power up. This prevents popping by timing the charging time of the 10pin and 11pin DC cutoff capacitors C3 and C4, and capacitor C8 for the 5pin ripple filter. Therefore, to obtain sufficient effect, it is recommended to use the constants of the application circuit in C3, C4, R3, R4, C8 and R8.