M51957A,B/M51958A,B
Independent
VCC
1
VCC
2
VCC
Independent
Input
Power-supply
Power-supply
Input
Output
Output
M51957
M51958
M51957
M51958
Vin
Vin
VCC
GND
GND
Delay capacitor
Cd
GND
Delay capacitor
Cd
Example 1. Independent power supply system
Please do enough verifying about
transition characteristic of VCC1
and VCC2.
Example 2. Logic pulse input
(not recommended)
Figure 7
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.
R1 + R2
VS = 1.25 ×
+ Iin × R1
R2
error margin
VCC
Power-supply
R1
Iin
→
Output
M51957
M51958
Vin
R2
Input
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.
REJ03D0778-0200 Rev.2.00 Aug 20, 2007
Page 9 of 13
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