BD4746G-TR データシートの表示（PDF） - ROHM Semiconductor
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BD4746G-TR Datasheet PDF : 8 Pages
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BD47□□G series
Technical Note
Explanation of Operation
BD47□□G series has the detection voltages and release voltages as threshold voltages and, as the voltages applied to the
input reach their respective threshold voltages, the output switches from “High” to “Low” and from “Low” to “High”. The
release voltage has a hysteresis that is the detection voltage +50mV (Typ.), preventing chattering in the output. When the
input is greater than the release voltage, the output is in a “High” state. When the input is lowered from that state, the output
switches to “Low” on the detection voltage. When the input is less than the detection voltage, the output is in a “Low” state.
When the input is raised from that state, the output switches to “High” with the release voltage. Additionally, at least 0.85V is
required for the circuit to operate fully. When the input falls below the operating limit voltage, the output becomes unsettled.
VDD
VDD
VS+ΔVS
VS
⑤
VOPL
0V
VOUT
VOH
TPHL
VOL
TPLH
TPHL
TPLH
①②
③④
Fig.11 Timing Waveform
1 When the power supply is turned on, the output is unsettled from after over the operating limit voltage (VOPL) until
TPHL. Therefore it is possible that the reset signal is not outputted when the rise time of Vcc is faster than TPHL.
2 When Vcc is greater than VOPL but less than the reset release voltage (VS + ΔVS), the output voltages will switch to
Low.
3 If Vcc exceeds the reset release voltage (VS + ΔVS), then VOUT switches from L to H.
4 If Vcc drops below the detection voltage (VS) when the power supply is powered down or when there is a power supply
fluctuation, VOUT switches to L (with a delay of TPHL).
5 The potential difference between the detection voltage and the release voltage is known as the hysteresis width (ΔVS).
The system is designed such that the output does not flip-flop with power supply fluctuations within this hysteresis width,
preventing malfunctions due to noise.
<Precautions>
Please be aware that when there is resistance on the power supply line, the detection voltage varies with voltage drops
caused by the IC current consumption.
Please connect a capacitor between VCC and GND when the power supply line has high impedance.
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2010.04 - Rev.C
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