BD49E54 データシートの表示（PDF） - ROHM Semiconductor
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BD49E54 Datasheet PDF : 10 Pages
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BD48□□G, BD48□□FVE, BD49□□G, BD49□□FVE series
Technical Note
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.)
V1
R2
I1
R1
CIN
VDD
BD48□□□
BD49□□□
GND
VOUT
CL
Fig.18
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.
IDD
Through Current
0
VDET
VDD
Fig.19 Current Consumption vs. Power Supply Voltage
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© 2009 ROHM Co., Ltd. All rights reserved.
2009.04 - Rev.A
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