BU4231G-TR Datasheet, PDF (12/16 Pages) Rohm – Low Voltage Free Delay Time Setting CMOS Voltage Detector IC Series

BU42xx series BU43xx series
Datasheet
3) Examples of the power supply with resistor dividers
In applications wherein the power supply input terminal (VDD) of an IC has resistor dividers, it is possible that an in-rush
current will momentarily flow into the circuit when the output logic switches, resulting in malfunctions (such as output
oscillations).
(In-rush 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
BU 42 xx
BU 43 xx
VOUT
GND
CL
0
VDET
VDD
Fig.21
A voltage drop [in-rush current (I1)] × [input resistor (R2)] is caused by the in-rush current, and causes the input voltage
to drop 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 in-rush current stops flowing through output
“Low”, and the voltage drop is reduced. As a result, the output switches from “Low” to “High”, which again causes the
in-rush current to flow and the voltage to drop. This operation repeats and will result to oscillation.
Consider the use of BU42xx when the power supply input has resistor dividers.
V D D - ID D P eak C urrent Ta=25°C
B U 49xx,B U 43xx
10
2.5
B U 48xx,B U 42xx
B D 52xx
B D 53xx
2.0
1
1.5
0.1
1.0
0.01
0.5
Tem p - ID D (B U 42xx)
V D D 3V
V D D 6V
V D D 7V
V D D 4V
0.001
3 4 5 6 7 8 9 10
V D D [V ]
0.0
-50 -30 -10 10 30 50 70 90 110 130
Tem p
Fig.22 Current Consumption vs. Power Supply Voltage
* This data is for reference only.
The figures will vary with the application, so please confirm the actual operating conditions before use.
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TSZ22111・15・001
12/13
TSZ02201-0R7R0G300050-1-2
22.May.2013 Rev.006