R3131N38HA Просмотр технического описания (PDF) - RICOH Co.,Ltd.

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производитель

R3131N38HA

Low Voltage Detector with Built-in Delay Circuit

RICOH Co.,Ltd. 

R3130N/R3131N

OPERATION

• Operation of R3130N Series

Ra

Vref Rb

+

Delay

-

Circuit

Comparator

VDD

Pch

OUT

Nch

⋅ CMOS output type

OUT pin is connected to the drain of

Nch Tr. and Pch Tr. in this IC.

⋅ Nch open drain output type

OUT pin is connected to the drain of

Nch Tr. in this IC. (OUT pin should be

pulled up to VDD or an external voltage

level.)

Supply

Voltage

(VDD)

Block Diagram

1

2

3

A

GND

4

5

B

Detector Threshold(VDET)

=Released Voltage

Minimum Operating

Voltage(VDDL)

GND

Output

Voltage

(OUT)

Tdelay

GND

Operating Diagram

In the above diagram,

1 Output voltage becomes equal to supply voltage (Nch open drain output Type; equal to pull-up Voltage).

2When supply voltage is down to the detector threshold level (Point A), Vref >= VDD× Rb/(Ra+Rb) is true. Then,

Output of the comparator is reversed, thus output voltage becomes equal to GND level.

3 When supply voltage is lower than minimum operating voltage, output of transistor is indefinite, therefore

output is also indefinite.

4 Output voltage is equal to GND level.

5 When supply voltage is higher than released voltage (Point B), Vref <= VDD× Rb/(Ra+Rb) is true. Then output

of the comparator is reversed, thus output voltage becomes equal to supply voltage (Nch open drain output

type; equal to pull-up voltage).

∗ There is no hysteresis range between detector threshold and released voltage.

16

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