M51957A Ver la hoja de datos (PDF) - Renesas Electronics

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M51957A

VOLTAGE DETECTING/ SYSTEM RESETTING IC SERIES

Renesas Electronics 

M51957A,B/M51958A,B

Independent

VCC1

VCC2

Input

Vin

Power-supply

M51957

M51958

Output

GND

Delay capacitor

Cd

Vin

VCC

GND

VCC

Independent

Power-supply

Input

M51957

M51958

Output

GND

Delay capacitor

Cd

Example 1. Independent power supply system

Please do enough verifying about

transition characteristic of VCC1

and VCC2.

Figure 7

Example 2. Logic pulse input

(not recommended)

3. Calculation of detecting voltage

Detecting voltage Vs can be calculated by the following expression.

However, the error margin is caused in the detecting voltage because input current Iin (standard 100 nA) exists if it

sets too big resistance.

Please set the constant to disregard this error margin.

VS = 1.25 ×

R1 + R2

R2

+ Iin × R1

error margin

VCC

R1

Iin

Vin

→

Input

Power-supply

M51957

M51958

Output

R2

GND

Delay capacitor

Cd

Figure 8 Influence of Input Current

4. About the voltage input outside ratings

Please do not input the voltage outside ratings to the input terminal.

An internal protection diode becomes order bias, and a large current flows.

REJ03D0778-0300 Rev.3.00 Sep 18, 2007

Page 9 of 13

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