Technical Note

6/9

BD45

□□□G, BD46□□□G series

www.rohm.com

2009.05 - Rev.C

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

 Circuit Applications

1) Examples of a common power supply detection reset circuit.

Application examples of BD45

□□□G series (Open Drain

output type) and BD46

□□□G series (CMOS output type)

are shown below.

CASE1: the power supply of the microcontroller (VDD2)

differs from the power supply of the reset detection

(VDD1).

Use the open drain output type (BD45

□□□G) attached a

load resistance (RL) between the output and VDD2. (As

shown Fig.18)

CASE2: the power supply of the microcontroller (VDD1) is

same as the power supply of the reset detection (VDD1).

Use CMOS output type (BD46

□□□G) or open drain output

type

(BD45

□□□G) attached a load resistance (RL)

between the output and Vdd1. (As shown Fig.19)

When a capacitance CL for noise filtering 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) The following is an example of a circuit application in which an OR connection between two types of detection voltages

resets the microcontroller.

When there are many power supplies of the system, power supplies VDD1 and VDD2 are being monitored separately, and

it is necessary to reset the microcomputer, it is possible to use an OR connection on the open drain output type BD45

□□□G

series to pull-up to the desired voltage (VDD3) as shown in Fig. 20 and make the output “High” voltage matches the power

supply voltage VDD3 of the microcontroller.

GND

microcontroller

BD45□□□

No.1

ER

ER

BD45□□□

No.2

GND

BD45□□□

Microcontroller

（Noise-filtering

Capacitor）

Fig.18 Open Collector Output Type

（Noise-filtering

Capacitor）

GND

BD46□□□

Microcontroller

Fig.19 CMOS Output Type

Fig.20