R3111x

12

 R3111E (TO-92) is the discontinued product as of April, 2017.

OPERATION

 Operation of R3111xxxxA

Vref

Ra

Rb

Rc

VDD

OUT

GND

Tr.1

Nch

Comparator

OUT pin should be pulled-up to

VDD or an external voltage level.

Block Diagram (R3111xxxxA)

13

5

A

B

tPLH

2

4

GND

GND

VDDL

-VDET

+VDET

Detector Threshold

Released Voltage

Minimum Operating Voltage

Pull-up Voltage

Detector Threshold

Hysteresis

Supply Voltage

(VDD)

Output Voltage

(VOUT)

Step

1

2

3

4

5

Comparator (

)

Pin Input Voltage

I

II

II

II

I

Comparator Output

H

L

Indefinite

L

H

Tr.1

OFF ON Indefinite ON OFF

Output Tr.

Nch

OFF ON Indefinite ON OFF

I

VDD

Rb

Rc

Ra

RbRc

II

VDD

Rb

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