BA5204F データシートの表示（PDF） - ROHM Semiconductor

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BA5204F

3V / 35mW dual power amplifier

ROHM Semiconductor 

Audio ICs

FInternal circuit configuration

BA5204F

FCircuit description (refer to the Internal Circuit diagram)

(1) Preamplifier Stage

The preamplifier is comprised of the level-shift transistor

Q101, a differential amplifier (Q102 and Q105), and the active

load (Q103 and Q106). The input is a PNP transistor that

does not require a coupling capacitor.

(2) Pre-drive stage

Q118 is the pre-drive transistor. Q122 and Q120 form the

load.

(3) Power stage

Comprised of phase-inverting transistor Q120, and power

transistors Q122 and Q123.

(4) Idling current setting circuit

The idling current is controlled so that the difference be-

tween the VBE of the power transistor Q122 and the VBE of

the phase-inverting transistor Q120 is the same as the dif-

ference between the VF of the constant-voltage diode

Q117 and the VBE of Q121.

(5) Negative-feedback circuit

The closed-circuit gain with negative feedback is deter-

mined by R108, R102, and the value of the resistor con-

nected to the NFB pin. Part of the gain setting resistance

is on the chip (R102) to reduce variance between compo-

nents.

(6) “Pop” noise elimination circuit

The IC has an internal timing circuit (with switch for op-

eration) to reduce the “pop” noise that occurs when pow-

er is applied.

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