BU42XXG_09 Datasheet, PDF (7/12 Pages) Rohm – Low Voltage Free Delay Time Setting CMOS Voltage Detector IC Series

BU42□□G series, BU42□□F series, BU42□□FVE series,
BU43□□G series, BU43□□F series, BU43□□FVE series
Technical Note
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.)
V1
IDD
R2
I1
VDD
Through
Current
R1
CIN
BU42□□
BU43□□
VOUT
CL
GND
0
VDET
VDD
Fig.20
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.
Consider the use of BU42□□ when the power supply input it with resistor dividers.
VDD - IDD Peak Current Ta=25°C
BU43xx
BU42xx
10
BD52xx
2.5
BD53xx
2.0
1
Temp - IDD(BU42xx)
VDD3V
VDD6V
VDD7V
VDD4V
1.5
0.1
1.0
0.01
0.5
0.001
3
4
5
6
7
8
9 10
VDD[V]
0.0
-50 -30 -10 10 30 50 70 90 110 130
Temp
Fig.21 Current Consumption vs. Power Supply Voltage
* This data is for reference only.
The figures will vary with the application, so please confirm actual operating conditions before use.
www.rohm.com
© 2009 ROHM Co., Ltd. All rights reserved.
7/11
2009.11 - Rev.C