bd4729gg-tr ROHM Co. Ltd., bd4729gg-tr Datasheet - Page 4

• Manufacturer Part Number: bd4729gg-tr
• Description: Bipolar Voltage Detector Ics
• Manufacturer: ROHM Co. Ltd.

 Explanation of Operation
© 2010 ROHM Co., Ltd. All rights reserved.
BD47□□G series
www.rohm.com
<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.
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.
TPHL. Therefore it is possible that the reset signal is not outputted when the rise time of Vcc is faster than TPHL.
Low.
fluctuation, VOUT switches to L (with a delay of TPHL).
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.
1
2
3
4
5
When the power supply is turned on, the output is unsettled from after over the operating limit voltage (VOPL) until
When Vcc is greater than VOPL but less than the reset release voltage (VS + ΔVS), the output voltages will switch to
If Vcc exceeds the reset release voltage (VS + ΔVS), then VOUT switches from L to H.
If Vcc drops below the detection voltage (VS) when the power supply is powered down or when there is a power supply
The potential difference between the detection voltage and the release voltage is known as the hysteresis width (ΔVS).
V
V
DD
OUT
0V
V
V
V
OH
OL
S
+ΔV
V
OPL
V
T
V
DD
PHL
S
S
Fig.11 Timing Waveform
①
②
4/7
T
PLH
③
T
PHL
④
T
PLH
⑤
Technical Note
2010.04 - Rev.C