LA4192 데이터 시트보기 (PDF) - SANYO -> Panasonic

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LA4192

1 to 2.3W 2-Channel of Power Amplifier

SANYO -> Panasonic 

LA4192

Externally connected components and comments

C1 (C2) : Feedback capacitor : The lower cut-off frequency is given by the following formula :

fL=

1

2πC1Rf

fL : Lower cut-off frequency

Rf : Feedback resistance

This requires careful review, because, together with decoupling capacitor, it affects the starting time.

R1 (R2) : Feedback resistor : Voltage gain is determined by ratio to the built-in resistor. Use ±5%-tolerance resistors to

enhance balance of voltage gains for the two channels.

C3 (C4) : Bootstrap capacitor : Capacitance affects output in the low-frequency range ; employment of small-value

capacitance causes reduced outputs in lower frequencies. Employ at least 47µF.

C5 (C6) : De-oscillating capacitor : Use a mylar capacitor that excels in temperature and frequency characteristics. If an

aluminum electrolytic or a ceramic capacitor is used, it may cause oscillation.

C7 (C8) : Output capacitor : The lower cut-off frequency is given by the following formula :

fL=

1

2πC7RL

fL : Lower cut-off frequency

RL : Load resistance

C9 :

C10 :

To obtain equivalent low-frequency characteristics for 2-channel operation with bridge amplifier connected,

double the capacitance.

Decoupling capacitor : Though this is an arm of the ripple filter, rejection effects saturate at a certain value so

that excessively large values do not serve any further purpose. It is employed for a time constant of the muting

circuit, so it affects the starting time.

Power supply capacitor.

Concerning application circuits

1. Voltage gain adjustments

♦ 2-channel

Voltage gain is determined by resistor R1 (R2) and an

externally connected feedback resistor Rf in accordance

with the following formula :

VG=20 log

R1 (R2)

Rf

[dB]

By suitable selection of the externally connected re-

sistor Rf, any voltage gain can be obtained. It is pref-

erable, however, that the voltage gain is chosen in the

range of 45dB to 50dB. Incidentally, R1 (R2) =10kΩ

typ.

♦ Bridge Amplifier.

A bridge amplifier connection is structured as shown above. Ch-1 functions as a non-inverting amplifier and Ch-2

as an inverting amplifier. For input to ch-2, output of ch-1 is divided by resistors R3 and R4 and is led out at pin 1

as bridge amplifier output. Attenuation of ch-1 output is R3/R4, while amplification of ch-2/ (RNF+R4), and due to

designation for R3 : 5kΩ typ., and R4 : 50Ω typ., ch-1 output attenuation and ch-2 amplification become equal by

designating RNF=51Ω. When obtained at ch-2, output is the same output as ch-1 but opposite in phase. Accord-

ingly, the overall voltage gain exhibited is 6dB above ch-1 gain, and is approximately given by the following

formula.

Continued on next page.

No.919–4/11

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