BA3911 データシートの表示（PDF） - ROHM Semiconductor

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BA3911

Reference voltage power supply

ROHM Semiconductor 

Regulator ICs

FOperation notes

(1) Example of application

The application circuit of Fig. 3 is recommended for use.

Make sure to confirm the adequacy of parts characteris-

tics. When using the circuit with changes to external cir-

cuit constants, make sure to leave sufficient margins in

consideration of fluctuations in the IC and external com-

ponents including static and transitional characteristics.

Note that ROHM has not carried out extensive survey re-

garding the patent right.

(2) 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.

(3) Power dissipation (Pd)

Refer to the heat reduction characteristics (Fig. 4) and

the rough estimation of IC power dissipation given on a

separate page. Make sure your design allows a maxi-

mum power within the operating temperature range.

(4) Overvoltage protection circuit

The overvoltage protection circuit turns OFF each output

when the potential difference between VCC (pin 7) and

GND (pin 12) is more than about 26V at normal tempera-

ture. Make sure to use the IC within this voltage limit.

(5) Preventing oscillation at each output

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

pacitor having a capacitance of 10µF or greater between

GND and each of the VDD (pin 5), AMP (pin 6), ANT (pin

8), COM (pin 9), AM (pin 10), and FM (pin 11) output pins.

We recommend using a tantalum electrolytic capacitor

whose capacitance is unsusceptible to temperature.

BA3911

(6) Overcurrent protection circuit

An overcurrent protection circuit is installed on each of

the VDD (pin 5), AMP (pin 6), ANT (pin 8), COM (pin 9),

AM (pin 10), and FM (pin 11) outputs, based on the re-

spective output current. This prevents IC destruction by

overcurrent, 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. The circuit should be carefully

set because output current is further restricted when out-

put voltage is less than 1VF (considered as short mode).

(7) Thermal protection circuit

A built-in thermal protection circuit prevents thermal

damage to the IC. All outputs except VDD are switched

OFF when the circuit operates, and revert to the original

state when temperature drops to a certain level.

(8) Grounding

Each ground line in the application circuit of Fig. 3 must

be adequately short regarding the GND pin (pin 12).

Make sure to arrange the ground lines in a pattern that

prevents mutual interference.

(9) Although the quality of this IC is rigorously con-

trolled, the IC may be destroyed when applied voltage or

operating temperature exceeds their absolute maximum

ratings. Because short mode or open mode cannot be

specified when the IC is destroyed, be sure to take physi-

cal safety measures such as fusing if special mode is ex-

pected.

(10) We recommend installing a bypass line in particular

applications if there is a mode where potential difference

between each output and input (VCC) or GND is reversed

from the normal state.

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