BA3528 Ver la hoja de datos (PDF) - ROHM Semiconductor

Número de pieza

componentes Descripción

Fabricante

BA3528

Pre / power amplifier and motor governor for 3V headphone stereos

ROHM Semiconductor 

Audio ICs

BA3528AFP / BA3529AFP

(6) Motor speed setting

To control the motor speed, the stable built-in reference

voltage VREG is divided across R4 and R5, and this voltage

is used as the speed control voltage. The balance condi-

tions for the bridge circuit are as follows:

Ea = R1

R2

R3 *Ra Ia

R2

) 1)

R3

R5

R4)R5

VREG

(however, Ir tt Ia)

From this, the balance conditions for the load fluctuation

zero are:

Ra = 10

Ea = 11

R1

R5

R4)R5

VREG

However, if Ra t 10 R1, the amount of positive feed-

back increases, and the circuit will be unstable, so within

the operating temperature range, always make

Ra y 10 R1 (see Fig. 17).

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 VCC = 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.

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