BD4940G-TR Datasheet, PDF (13/18 Pages) Rohm – Standard CMOS Voltage Detector IC

BD48xxx series BD49xxx series
Datasheet
●Circuit Applications
1) Examples of a common power supply detection reset circuit.
VDD1
BD48xxx
VDD2
RL
Micro
RST _controller
CL
( capacitor is for
noise filtering ）
GND
Application examples of BD48xxx series (Open Drain
output type) and BD49xxx series (CMOS output type)
are shown on the left.
CASE1: Power supply of the microcontroller (VDD2)
differs from the power supply of the reset detection IC
(VDD1).
Use an open drain output type (BD48xxx) device with a
load resistance RL attached as shown in figure 15.
Fig.15 Open Drain Output Type
VDD1
CASE2: Power supply of the microcontroller (VDD1) is
same as the power supply of the reset detection IC
(VDD1).
Use a CMOS output type (BD49xxx) device or an open
drain device with a pull up resistor between output and
VDD1.
GND
BD49xxx
Micro
RST _controller
C_L
( capacitor is for
filtering）
When a capacitance CL for noise filtering is connected to
the VOUT pin (the reset signal input terminal of the
microcontroller), please take into account the rise and
fall waveform of the output voltage (VOUT).
The Electrical characteristics were measured using
RL= 470kΩ and CL = 100pF.
Fig.16 CMOS Output Type
2) The following is an example of a circuit application in which an OR connection between two types of detection voltage
resets the microcontroller.
VDD1
VDD2
VDD3
BD48xxx
BD48xxx
RL
Microcontroller
RST
Fig.17
GND
To reset the microcontroller when many independent power supplies are used in the system, OR connect an open drain
output type (BD48xxx series) to the microcontroller’s input with pull-up resistor to the supply voltage of the microcontroller
(VDD3) as shown in Fig. 17. By pulling-up to VDD3, output “High” voltage of micro-controller power supply is possible.
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TSZ22111・15・001
13/15
TSZ02201-0R7R0G300030-1-2
22.May.2013.Rev.008