Audio ICs
(6) Motor speed setting
To control the motor speed, the stable built-in reference
voltage V
REG
is divided across R
4
and R
5
, and this voltage
is used as the speed control voltage. The balance condi-
tions for the bridge circuit are as follows:
E
a
= R
1
R
2
R
3
R
2
R
3
*R
a
I
a
R
5
R
4
)R
5
BA3528AFP / BA3529AFP
R
1
, the amount of positive feed-
However, if R
a
t
10
back increases, and the circuit will be unstable, so within
the operating temperature range, always make
R
a
y
10
R
1
(see Fig. 17).
)
1)
V
REG
(however, Ir
tt
Ia)
From this, the balance conditions for the load fluctuation
zero are:
R
a
= 10
E
a
= 11
R
1
R
5
R
4
)R
5
V
REG
FOperation
notes
(1) Application circuits
Provided the recommended circuit constants are used,
the application circuits should function correctly. Howev-
er, we recommend that you confirm the characteristics of
the circuits in actual use. If you change the circuit
constants, check both the static and transient character-
istics of the circuit, and allow sufficient margin to accom-
modate variations between both ICs and external com-
ponents.
(2) Recommended supply voltage
The values given in the electrical characteristics table are
guaranteed only for Ta = 25_C, and V
CC
= 3V. However,
as long as the IC is operated within the recommended
operating temperature and supply voltage ranges, the
general circuit functions are guaranteed to operate cor-
rectly, and there will not be significant changes in the
electrical characteristics.
(3) Power dissipation
The internal power dissipation of the IC is depends
strongly on the value of the load resistance and the sup-
ply voltage.
For this reason, when designing sets for mass produc-
tion, pay due consideration to the power dissipation char-
acteristics of the IC with respect to ambient temperature
and supply voltage (see Figs. 18 and 19). Note, that the
maximum allowed power dissipation is 1.7W at 25_C,
and this decreases by 13.6mW for each increase in tem-
perature of 1_C over this.
(4) PCB layout
In certain cases, the external circuit wiring can induce os-
cillations in the IC or degrade circuit performance. To
avoid this, design the PCB wiring in such a way as to keep
external wiring as short as possible, and ensure that it
does not have common impedance.
395
ROHM [ ROHM ]
