Audio ICs
1.5V / 15mW dual power amplifier
BA5152F
The BA5152F is a dual-channel power amplifier designed for 1.5V headphone stereos. The circuit consists of a power
supply circuit, mute circuit, bias circuit, and two amplifier circuits. To simplify assembly, the gain is fixed, so external nega-
tive-feedback components are not required.
FApplications
1.5V headphone Hi-Fi stereos
FFeatures
1) High output. P
OUT
= 15mW (R
L
= 16Ω).
2) Small “pop” noise.
3) Mute circuit terminal provided.
4) Terminals provided for radiation countermeasures.
FBlock
diagram
5)
6)
7)
8)
Good ripple rejection ratio.
Few external components required.
Good low-voltage characteristics.
Built-in power switch circuit.
FAbsolute
maximum ratings (Ta = 25_C)
367
Audio ICs
FRecommended
operating conditions (Ta = 25_C)
BA5152F
FElectrical
characteristics (unless otherwise noted, Ta = 25_C, V
CC
= 1.5V, f= 1kHz and R
L
= 16Ω)
FMeasurement
circuit
368
Audio ICs
FApplication
example
BA5152F
FApplication
board patterns
FApplication
board component layout
369
Audio ICs
FComplete
application example circuit
BA5152F
FCircuit
description
(1) Power supply block
The BA5152F has an internal power switch, so the V
CC
terminal (pin 9) connects directly to the power source. Pin
13 is the power switch, and if it is left open, no bias current
flows in the circuit and the IC will not operate.
(2) Mute circuit block
When pin 13 is connected to V
CC
, the IC starts up, but the
mute circuit operates to suppress a “pop” sound from be-
ing generated. The time constant of the power-on mute
circuit is determined by the capacitor connected between
pins 14 and 15. It is also possible to force the mute circuit
to operate by connecting pin 16 to V
CC
. There is no time
constant in this case.
370
Audio ICs
(3) Bias block
The components connected to pins 2, 3, and 4 set the
bias point and V
ODC
. When pin 2 is open circuit, and V
CC
= 1.25V, the output pin V
ODC
voltage is internally set to
1 / 2V
CC
. By connecting a resistor to pin 2 and changing
the voltage divider ratio, it is possible to vary V
ODC
.
Pins 3 and 4 are shorted and connected to earth via an
electrolytic capacitor to generate the bias point. When a
33µF component is used, it is possible to obtain 45dB of
ripple rejection. This can be improved if pins are indepen-
dently grounded through capacitors.
BA5152F
(4) Amplifier block
The amplifier circuits have a fixed gain of G
V
= 21dB. The
negative-feedback circuits are on the chip, and the
ground point of the negative-feedback circuit uses the
bias point as its reference, so connect the input poten-
tiometer to the bias point pins (3 and 4). Connect bypass
capacitors to the output pin to prevent oscillation. When
the IC is used in sets containing an AM radio, it is possible
to reduce unnecessary radiation from the power amplifi-
ers by connecting CR circuits to pins 6 and 11.
FElectrical
characteristics curves (Ta = 25_C)
371
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