BU48XXG_11 Datasheet, PDF (6/9 Pages) Rohm – Low Voltage Standard CMOS Voltage Detector ICs

BU48□□G Series, BU48□□F Series, BU48□□FVE Series,
BU49□□G Series, BU49□□F Series, BU49□□FVE Series
Technical Note
●Circuit Applications
1) Examples of a common power supply detection reset circuit
VDD1
CIN
V DD1
CIN
GND
VDD2
Application examples of BU48□□G/F/FVE series
RL
Microcontroller
(Open Drain output type) and BU49□□G/F/FVE series
(CMOS output type) are shown below.
BU48□□□
RST
CASE1:The power supply of the microcontroller (VDD2) differs
from the power supply of the reset detection (VDD1).
CL
Use the Open Drain Output Type (BU48□□G/FVE)
(Capac it or for
noise filtering)
Fig.15 Open collector Output type
attached a load resistance (RL) between the output and
GND
VDD2. (As shown Fig.15)
CASE2:The power supply of the microcontroller (VDD1) is same
as the power supply of the reset detection (VDD1).
Use CMOS output type (BU43□□G/FVE) or Open Drain
Output Type (BU48□□G/FVE) attached a load
BU49□ □□
Microcontroller
RST
resistance (RL) between the output and VDD1.
(As shown Fig.16)
CL
(Capacitor for
nois e filtering)
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).
Fig.16 CMOS Output type
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.
V1
R2
I1
CIN
R1
VDD
BU48□□
BU49□□
GND
VOUT
CL
Fig.17
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2011.03 - Rev.D