BD45381 ROHM [Rohm], BD45381 Datasheet - Page 7

• Manufacturer Part Number: BD45381
• Description: Counter Timer Built-in CMOS Voltage Detector IC
• Manufacturer: ROHM [Rohm]

© 2009 ROHM Co., Ltd. All rights reserved.
BD45□□□G, BD46□□□G series
www.rohm.com
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.)
A voltage drop of [the through-current (I1)] × [input resistor (R2)] is caused by the through current, and the input voltage to
descends, when the output switches from “Low” to “High”. When the input voltage decreases and falls below the detection
voltage, the output voltage switches from “High” to “Low”. At this time, the through-current stops flowing through output
“Low”, and the voltage drop is eliminated. As a result, the output switches from “Low” to “High”, which again causes the
through current to flow and the voltage drop. This process is repeated, resulting in oscillation.
0
I
DD
V1
Fig.22 Current Consumption vs. Power Supply Voltage
R2
R1
CIN
V
DET
I1
ER
Through Current
Fig.21
7/9
BD45□□□G
BD46□□□G
V
DD
GND
C
L
V
OUT
V
DD
Technical Note
2009.05 - Rev.C