R3111Q601B-TR-F Просмотр технического описания (PDF) - RICOH Co.,Ltd.

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R3111Q601B-TR-F

LOW VOLTAGE DETECTOR

RICOH Co.,Ltd. 

R3111x

• Operation of R3111xxxxB

Ra

Rb

Vref

Rc

Comparator

VDD

OUT pin should be pulled-up to

OUT VDD or an external voltage level.

Nch

Tr.1

GND

Block Diagram (R3111xxxxB)

1

2

3

Released Voltage +VDET

A

Detector Threshold -VDET

Supply Voltage

(VDD)

Minimum Operating Voltage VDDL

GND

Detector Threshold B

Hysteresis

Step

123

Comparator (+)

Pin Input Voltage

I II I

Comparator Output L H L

Tr.1

OFF ON OFF

Output Tr. Nch ON OFF ON

Pull-up Voltage

Output Voltage

(VOUT)

GND

Output

Delay Time

tPLH

Operation Diagram

I

Rb+Rc

Ra+Rb+Rc

×VDD

II

Rb

Ra+Rb

×VDD

• Explanation of operation

Step 1. The output voltage is equal to the GND level.

Step 2. At Point “A”, Vref >= VDD×(Rb+Rc)/(Ra+Rb+Rc) is true, as a result, the output of comparator is reversed

from "L" to "H", therefore the output voltage becomes the pull-up voltage. The voltage level of Point A

means a detector threshold voltage (−VDET).

Step 3. At Point “B”, Vref <= VDD×Rb/(Ra+Rb) is true, as a result, the output of comparator is reversed from "H" to

"L", then the output voltage is equal to the GND level. The voltage level of Point B means a released

voltage (+VDET).

∗) The difference between a released voltage and a detector threshold voltage is a detector threshold hysteresis.

15

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