BA3960 Просмотр технического описания (PDF) - ROHM Semiconductor

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BA3960

Dual circuit, variable output voltage regulator

ROHM Semiconductor 

Regulator ICs

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 presented

on a separate page. If power dissipation exceeds the al-

lowable limit, the functionality of IC will be degraded

(such as reduction of current capacity by increased chip

temperature). Make sure to use the IC within the allow-

able 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 of the Active 1 and 2 output pins. Oscilla-

tion can occur if capacitance is susceptible to tempera-

ture. We recommend using a tantalum electrolytic capac-

itor with minimal changes in capacitance. Also, output

can be further stabilized by connecting a bypass capaci-

tor between VCC and GND.

(4) Overcurrent protection circuit

An overcurrent protection circuit is installed on the Active

1 and 2 outputs, based on the respective current capac-

ity. This prevents IC destruction when the load is short-

circuited, by limiting the current with a curve shape of “7”

in the voltage-current graph. The IC is designed with

margins so that current flow will be restricted and latching

will be prevented even if a large current suddenly flows

through a large capacitor. Note that these protection cir-

cuits are only good for preventing damage from sudden

accidents. Make sure your design does not cause the

protection circuit to operate continuously under transi-

tional conditions (for instance, if output is clamped at 1VF

or higher, short mode circuit operates at 1VF or lower).

Note that the circuit ability is negatively correlated with

temperature.

BA3960

(5) Thermal protection circuit

A built-in thermal protection circuit prevents thermal

damage to the IC. All outputs are switched OFF when the

circuit operates, and revert to the original state when

temperature drops to a certain level.

(6) Grounding

To minimize the variation of output voltage due to varia-

tions in load current, the GND (pin 1, for large current)

and the PRE GND (pin 3, for small current) pins are sepa-

rately provided. Make sure to connect circuits to correct

pins.

(7) Output voltage setting

ROHM recommends using a 3.9kΩ resistor for R12 and

R22. Refer to a separate page for the output voltage set-

ting. Note that making a large change to the R12 and R22

values will affect the current capacity.

(8) MODE voltage

Due to the IC’s internal structure, a reverse current flow

will occur if the MODE voltage exceeds the VCC voltage.

Make sure to avoid this.

FExternal dimensions (Units: mm)

140

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