189

Regulator ICs

BA3938

FApplication example

FOperation notes

(1)

Operating power supply voltage

When operating within proper ranges of power supply

voltage and ambient temperature, most circuit functions

are guaranteed. Although the rated values of electrical

characteristics cannot be absolutely guaranteed, char-

acteristic values do not change drastically within the

proper ranges.

(2)

Power dissipation (Pd)

Refer to the heat reduction characteristics (Fig. 5) and

the rough estimation of IC power dissipation given on a

separate page. If power dissipation exceeds the allow-

able limit, the functionality of IC will be degraded (such

as reduction of current capacity by increased chip tem-

perature). Make sure to use the IC within the allowable

range of power dissipation with a sufficient margin.

(3)

Preventing oscillation at each output

To stop oscillation of output, make sure to connect a ca-

pacitor having a capacitance of 10

µF or greater between

GND and each output pin. Oscillation can occur if capaci-

tance is susceptible to temperature. We recommend us-

ing a tantalum electrolytic capacitor with minimal

changes in capacitance. Also, output can be further sta-

and GND.

(4)

Overcurrent protection circuit

An overcurrent protection circuit is installed in each out-

put system, based on the respective output current. This

prevents IC destruction by overcurrent, by limiting the

current with a curve shape of “7” in the voltage-current

) B). The

IC is designed with margins so that current flow will be re-

stricted and latching will be prevented even if a large cur-

rent suddenly flows through a large capacitor. Note that

these protection circuits are only good for preventing

damage from sudden accidents. Make sure your design

does not cause the protection circuit to operate continu-

ously under transitional conditions (for instance, if output

correlated with temperature.