RX5VT Datasheet, PDF (18/31 Pages) RICOH electronics devices division – LOW VOLTAGE DETECTOR

OPERATION
VDD
Ra
+
–
Rb
Tr.1
Rc
Pch
OUT
Nch
• In R×5VT×A, Nch Tr. drain is
connected to OUT pin.
• In R×5VT×C, Nch Tr. drain
and Pch Tr. drain are connected
to OUT pin.
FIG. 1 Block Diagram
Operation Diagram
GND
12
3
45
Step
Step 1 Step 2 Step 3 Step 4 Step 5
Supply Volage
(VDD)
Released Volage +VDET
Detected Volage –VDET
Minimum Operating Volage
GND
B
A Detector Threshold Hysteresis
Output Volage
(OUT)
GND
FIG. 2 Operation Diagram
tPLH
Comparator(+) Pin
Input Voltage
I
II
II
II
I
Comparator Output H L Indefinite L H
Tr. 1
OFF ON Indefinite ON OFF
Pch ON OFF Indefinite OFF ON
Output Tr.
Nch OFF ON Indefinite ON OFF
Rb + Rc
I.
·VDD
Ra + Rb + Rc
Rb
II.
·VDD
Ra + Rb
Step 1. Output Voltage is equal to Power Source Voltage (VDD).
Step 2. When Input Voltage to Comparator reaches the state of Vref≥VDD·(Rb+Rc)/(Ra+Rb+Rc)at Point A (Detected Voltage –VDET), the output of Com-
parator is reserved, so that Output Voltage becomes GND.
Step 3. In the case of CMOS Output, Output Voltage becomes unstable when Supply Voltage (VDD) is smaller than Minimum Operating Voltage. In the
case of Nch Open Drain Output, a pulled-up voltage is output.
Step 4. Output Voltage becomes equal to GND.
Step 5. When Input Voltage to Comparator reaches the state of Vref≤VDD· (Rb)/(Ra+ Rb) at Point B (Released Voltage +VDET), the output of Comparator is reversed,
so that Output Voltage becomes equal to Supply Voltage (VDD).
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