R3115Z 데이터 시트보기 (PDF) - RICOH Co.,Ltd.

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R3115Z

LOW VOLTAGE DETECTOR WITH OUTPUT DELAY

RICOH Co.,Ltd. 

R3115Z

OPERATION

Current

Source

Vref

Ra Comparator

Rd

Schmitt Trigger

Rb

Tr.2

Tr.1

Rc

VDD

Pch

OUT

Nch

GND

CD

Fig. 1 Block Diagram with an external capacitor

1

Released Voltage +VDET

Detector Threshold −VDET A

Supply Voltage(VDD)

Minimum Operating −VDEL

Voltage

GND

Output Voltage(OUT)

GND

2

3

45

Operation Status 1 2

3

45

HYSTERESIS B

RANGE

Compartor (−) Pin

Input Voltage

Compartor Output L H Indefinite ON OFF

Tr.1,2

OFF ON Indefinite ON OFF

Delay

Time

Output

Tr.

Nch OFF ON Indefinite ON OFF

Pch ON OFF Indefinite OFF ON

Rb+Rc

Ra+Rb+Rc

×

VDD

Rb

Ra+Rb

× VDD

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 >= VDD×(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 <= VDD×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.

8

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