Ricoh R3111x Series Instrukcja Użytkownika Pobierz pdf (Strona 10)

R3114x

OPERATION

• Operation of R3114xxx1A

Vref

OUT

GND

Tr.1

Nch

Com

arato

OUT pin should be pulled-up to

or an external voltage level.

Block Diagram (R3114xxx1A)

13 5

PLH

2 4

GND

DDL

DET

Detector Threshold

Released Voltage

Minimum Operating Voltage

Pull-up Voltage

Detector Threshold

Hysteresis

Supply Voltage

)

Output Voltage

OUT

)

PHL

Detect

Delay Time

Step 1 2 3 4 5

Comparator (−)

Pin Input Voltage

I II II II I

Comparator Output L H Indefinite H L

Tr.1 OFF ON Indefinite ON OFF

Output Tr. Nch OFF ON Indefinite ON OFF

×V

Rb+Rc

Ra+Rb+Rc

×V

Ra+Rb

Operation Diagram

• Explanation of operation

Step 1. The output voltage is equal to the pull-up voltage.

Step 2. At Point "A", Vref

VDD×(Rb+Rc)/(Ra+Rb+Rc) is true, as a result, the output of comparator is reversed

from "H" to "L", therefore the output voltage becomes the GND level. The voltage level of Point A means

a detector threshold voltage (

−VDET).

Step 3. When the supply voltage is lower than the minimum operating voltage, the operation of the output

transistor becomes indefinite. The output voltage is equal to the pull-up voltage.

Step 4. The output voltage is equal to the GND level.

Step 5. At Point "B", Vref

VDD×Rb/(Ra+Rb) is true, as a result, the output of comparator is reversed from "L" to

"H", then the output voltage is equal to the pull-up voltage. 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.

Output

Delay Time

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 30 31

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Ricoh R3111x Series Instrukcja Użytkownika Strona 10

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