s
OPERATION
V
DD
R
D
Tr.1
Tr.2
Nch
Rc
GND
Schmitt Trigger
Pch
OUT
Current Source
Ra
Comparator
-
+
Rb
Vref
Output Capacitor
C
D
Fig. 1 Block Diagram with an external capacitor
1
2
3
4
5
Released Voltage
+
VDET
Detector Threshold
Supply Voltage
VDDL
(VDD)
Minimum Operating
Voltage
GND
Operation Status
Comparator(-) Pin
Input Voltage
Comparator Output
Tr.1, 2
Nch
Output Tr.
1
Ι
L
OFF
OFF
ON
2
ΙΙ
H
ON
ON
OFF
3
ΙΙ
Indefinite
Indefinite
Indefinite
Indefinite
4
ΙΙ
H
ON
ON
OFF
5
Ι
L
OFF
OFF
ON
B
HYSTERESIS RANGE
-V
DET
A
Output Voltage
(OUT)
Delay Time
GND
Pch
Ι
ΙΙ
Rb+Rc
×V
DD
Ra+Rb+Rc
Rb
×V
DD
Ra+Rb
Fig. 2 Operation Diagram
1. Output Voltage is equal to Supply Voltage. (As for Nch Open Drain Type, equal to pull-up voltage.)
2. When the Supply Voltage is down to the detector threshold voltage level(Point A),
Vref≥V
DD×(
Rb+Rc)/(Ra+Rb+Rc) is true, then output of the comparator is reversed from “L” to “H”, therefore
Output Voltage becomes GND level.
3. When the Supply Voltage is lower than Minimum Operating Voltage, the operation of Output Transistor is
indefinite. In the case of Nch Open Drain Type, Output Voltage is equal to pull-up Voltage.
4. Output Voltage becomes GND level.
5. When the Supply Voltage is higher than released voltage (Point B), Vref≤V
DD×
Rb/(Ra+Rb) is true, then
Output of the comparator reaches the threshold level, and Output of Shmitt Trigger is reversed from “H” to
“L”, then Output Voltage is equal to Supply Voltage. (As for Nch Open Drain Type, equal to pull-up voltage.)
*) The difference between Released Voltage and Detector Threshold Voltage means Hysteresis Range
Voltage.
Rev. 1.10
-2-
RICOH [ RICOH ELECTRONICS DEVICES DIVISION ]
