M51945A Просмотр технического описания (PDF) - Renesas Electronics

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M51945A

Voltage Detecting, System Resetting IC Series

Renesas Electronics 

M51945A,B/M51946A,B

Independent

VCC1

VCC2

Input

Vin

Power-supply

M51945

M51946

Output

GND

Vin

VCC

GND

VCC

Independent

Power-supply

Input

M51945

M51946

Output

GND

Example 1. Independent power supply system

Please do enough verifying about

transition characteristic of VCC1

and VCC2.

Figure 4

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

M51945

M51946

Output

R2

GND

Figure 5 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.

REJ03D0774-0200 Rev.2.00 Aug 20, 2007

Page 7 of 10

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