RN5VD25C 데이터 시트보기 (PDF) - RICOH Co.,Ltd.

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RN5VD25C

VOLTAGE DETECTOR WITH OUTPUT DELAY

RICOH Co.,Ltd. 

RN5VD

OPERATION

Current Source

Ra Comparator RD

–

+

Rb

Tr.2

Tr.1

Rc

Schmitt Trigger

CD

Output Capacitor

FIG. 1 Block Diagram

VDD

Pch

OUT

Nch

GND

12

3

45

Released Voltage +VDET

Detected Voltage –VDET

Supply Voltage

(VDD)

Minimum Operaing Voltage

GND

B

A Detector Threshold Hysteresis

Step

Step 1 Step 2 Step 3 Step 4 Step 5

Comparator (–) Pin

Input Voltage

I II

II

II I

Comparator Output L H Indefinite H L

Tr. 1, 2

OFF ON Indefinite ON OFF

Nch OFF ON Indefinite ON OFF

Output Tr.

Pch ON OFF Indefinite OFF ON

Output Voltage

(OUT)

GND

FIG. 2 Operation Diagram

Delay Time

Rb + Rc

I.

· VDD

Ra + Rb + Rc

Rb

II.

· VDD

Ra + Rb

Step 1. Output Voltage is equal to Pull-up Voltage.

Step 2. When Input Voltage (VDD) reaches the state of Vref≥VDD · (Rb+Rc) / (Ra+Rb+Rc) at Point A (Detected Voltage –VDET) , the output of Comparator is

reversed, so that Output Voltage becomes GND. Discharging is performed from CD pin connected to External Capacitor. No delay time is generated.

Step 3. Output Voltage becomes indefinite when Power Source Voltage(VDD) is smaller than Minimum Operating Voltage. When the output is pulled up, VDD is

output.

Step 4. Output Voltage becomes equal to GND.

Step 5. When Input Voltage (VDD) reaches the state of Vref≤VDD · Rb/ (Ra+Rb) at Point B (Released Voltage +VDET) , the output of Comparator is reversed,

and the External Capacitor is charged through CD pin, so that Output Voltage becomes equal to Pulled-up Voltage after a delay time tD (=0.69×106×CD) .

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