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TSZ02201-0R7R0G300130-1-2

TSZ22111

･

15

･

001

11/14

17.May.2013 Rev.003

BU45Kxxxx, BU46Kxxxx, BU45Lxxxx, BU46Lxxxx series

Datasheet

Examples of the power supply with resistor dividers.

In applications wherein the power supply voltage of an IC comes from a resistor divider circuit, an in-rush current will flow

into the circuit when the output level switches from “High” to “Low” or vice versa. In-rush current is a sudden surge of

current that flows from the power supply (VDD) to ground (GND) as the output logic changes its state. This current flow

may cause malfunction in the systems operation such as output oscillations, etc.

Fig. 19

When an in-rush current (I1) flows into the circuit (Refer to Fig. 19) at the time when output switches from “Low” to “High”,

a voltage drop of I1×R2 (input resistor) will occur in the circuit causing the VDD supply voltage to decrease. When the VDD

voltage drops below the detection voltage, the output will switch from “High” to “Low”. While the output voltage is at “Low”

condition, in-rush current will stop flowing and the voltage drop will be reduced. As a result, the output voltage will switches

again from “Low” to “High” which causes an in-rush current and a voltage drop. This operation repeats and will result to

oscillation.

R2

BU45xxxxx

BU46xxxxx

GND

R1

I1

V1

CIN

0

In-rush Current

Fig. 20 Current Consumption vs. Power Supply Voltage