BU4836F-TR Datasheet, PDF (12/16 Pages) Rohm – Low Voltage Standard CMOS Voltage Detector ICs

BU48xx series BU49xx series
Datasheet
3) Examples of the power supply with resistor dividers
In applications where the power supply input terminal (VDD) of an IC is connected through 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
BU48xx
BU49xx
GND
VOUT
CL
Fig.18
0
VDET
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 BU48xx when the power supply input it with resistor dividers.
VDD - IDD Peak Current Ta=25°C
BU49xx,BU43xx
10
BU48xx,BU42xx
2.5
BD52xx
BD53xx
2.0
1
1.5
0. 1
1.0
0. 01
0.5
Tem p - ID D (B U 42xx)
VDD
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
VDD[V]
0.0
-50 -30 -10 10 30 50 70 90 110 130
Tem p
Fig.19 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.
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22.May.2013 Rev.008