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Power Management ICs Forum Discussions

Rina
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Rina_0-1659401627040.png

This is a patamenter about Buffer Capacitor of T5V1 listing in TLE88888-1QK Datasheet.We want to know whether it can be applied beyond the recommended parameters, because the ripple of our power supply will exceed the accuracy range due to the interference of the clock signal, and we must increase the capacitance of 4.7uf to filter it out.Is there any risk if 4.7uf capacitor is used?

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Jingwei
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Hi Rina,

Thanks for using Infineon Community.

From my point of view, I don't think there are problems with 4.7uf. 

But we can only guarantee all functions with the value in the DS.

Best regards 

Steven

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Rina
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Could you list some possible risk?Such as when and what kind of problem will it happen?If problems happened,where would it be affected?Could you provide some directions?

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Jingwei
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Hi Rina, 

as T5V1 is sensor supply, 400nF is good to filter out high frequency interference. Could you tell more about your circuit (design), or why you use 4.7uF near our IC?

Thanks

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Rina
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 because there is some interference of the clock signal that leads to the ripple of our power supply  exceeding the accuracy range , and we must increase the capacitance of 4.7uf to filter it out.

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Jingwei
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Could you provide the related schematic design (Power supply side and T5V1 signal side)?

Steven

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Rina
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Rina_0-1659571605257.png

This is our design for power supply,and now we want to add 4.7uF on T5V1,what kind of risks will it be?So that we can determine whether we need to choose other improvements.

 

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Jingwei
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I can't see the risks for using 4.7uF. But I would also recommend for using 100nF near T5V1, and 4.7uF near your power consumption side.

BR,

Steven

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Rina
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I can understand that if 100nF is placed near t5v1, there is no risk of 4.7uf increase, right?

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Jingwei
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Yes.

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Rina
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Here are some other qusetions——If we connect a 1KΩ resistor in series on SDO and CLK,is the value of resistor too large?is there some risk for SPI communication?Do you have recommended values or ranges?

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Jingwei
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Hi Rina,

If 1kOhm in your previous design had no problem with your data rate requirements. Then it is fine.

1kOhm has an effect on the slew rate.

330Ohm is recommended.

Best regards,

Steven

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Rina
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we didn't use 1KOhm in our previous design,and we have measured that the rising edge of the signal slows down but there is no distortion after adding 1kohm. If the waveform of SPI meets the timing requirements of the datasheet, could it be guaranteed that there is no risk?

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Jingwei
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It should be ok, but you should test on your own application. There's no guarantee.

Steven

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