Technical Note

6/8

BU48

□□G, BU48□□F, BU48□□FVE, BU49□□G, BU49□□F, BU49□□FVE series

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2009.06 - Rev.C

© 2009 ROHM Co., Ltd. All rights reserved.

 Circuit Applications

1) Examples of a common power supply detection reset circuit

Application examples of BU48

□□G/F/FVE series

(Open Drain output type) and BU49

□□G/F/FVE series

(CMOS output type) are shown below.

Use the Open Drain Output Type (BU48

□□G/FVE)

Use CMOS output type (BU43

□□G/FVE) or Open Drain

Output Type (BU48

□□G/FVE) attached a load

(As shown Fig.16)

When a capacitance CL for noise filtering or setting the

output delay time is connected to the Vout pin (the reset

signal input terminal of the microcontroller), please take

into account the waveform of the rise and fall of the

output voltage (Vout).

2) Examples of the power supply with resistor dividers

In applications where the power supply input terminal (VDD) of an IC with resistor dividers, it is possible that a

through-current will momentarily flow into the circuit when the output logic switches, resulting in malfunctions (such as

output oscillatory state).

(Through-current is a current that momentarily flows from the power supply (VDD) to ground (GND) when the output level

switches from “High” to “Low” or vice versa.)

Consider the use of BD48

□□ when the power supply input it with resistor dividers.

Fig.17

R2

BU48□□

BU49□□

GND

R1

I1

V1

BU48□□□

GND

Microcontroller

(Capac it or f or

noise filtering)

(Capacitor for

nois e filtering)

BU49□□□

Microcontroller

GND

Fig.15 Open collector Output type

Fig.16 CMOS Output type