Other Parts Discussed in Thread: , UCC28740
Dear Specialists,
My customer is considering UCC28742 and has a question.
I would be grateful if you could advise.
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I'm considering whether tstart time is <80ms.
Could you please let me know, as our system needs to be within 80ms.
According to the UCC28742EVM-001, start up time is almost 800ms
This value is calculated by equation(7). on the UCC28742 datasheet P.24, 1.09s.
In this case, Rstr is 15Mohm and CDD is 0.33uF.
In order to be tstart within 80ms, the product of RC must be 1/10 or less.
I gave two points that can be considered when the product of RC was reduced to 1/10.
(1)The power consumption of the resistor increases as the resistance value decreases.
(2)The cut-off frequency of the RC filter rises and the influence of noise increases.
(3)Is there any other possible disadvantage?
(4)Generally, I think that RSTR uses MΩ order, why is 100kΩ order not used?
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I appreciate your great help in advance.
Best regards,
Shinichi