m51945a Renesas Electronics Corporation., m51945a Datasheet - Page 7

• Manufacturer Part Number: m51945a
• Description: Voltage Detecting, System Resetting Ic Series
• Manufacturer: Renesas Electronics Corporation.

M51945A,B/M51946A,B
3. Calculation of detecting voltage
4. About the voltage input outside ratings
REJ03D0774-0300 Rev.3.00 Sep 18, 2007
Page 7 of 10
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.
Please do not input the voltage outside ratings to the input terminal.
An internal protection diode becomes order bias, and a large current flows.
V
Example 1. Independent power supply system
S
Vin
= 1.25 ×
V
CC
1
Independent
Input
Please do enough verifying about
transition characteristic of V
and V
R
1
GND
R
+ R
2
CC
2
2.
M51945
M51946
+ Iin × R
V
CC
error margin
Power-supply
2
V
Figure 5 Influence of Input Current
CC
R
R
Vin
1
2
1
Output
Input
CC
Iin
→
1
GND
Figure 4
M51945
M51946
Power-supply
GND
V
CC
Vin
Example 2. Logic pulse input
Output
Independent
Input
GND
(not recommended)
M51945
M51946
V
CC
Power-supply
Output