Ricoh R3111x Series Manual do Utilizador descarregar pdf (Página 11)

R3114x

• Operation of R3114xxx1C

Vref

OUT

GND

Tr.1

Nch

Pch

Com

arato

Block Diagram (R3114xxx1C)

PLH

GND

DDL

DET

Detector Threshold

Released Voltage

Minimum Operating Voltage

1 2 3 4 5

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

Pch ON OFF Indefinite OFF ON

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 supply voltage (VDD).

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.

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 supply voltage (V

DD). 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 ... 6 7 8 9 10 11 12 13 14 15 16 ... 30 31

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Ricoh R3111x Series Manual do Utilizador Página 11

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