LM7705: C10 Capacitor - What is the best capacitance to keep IC from getting damaged?

Naoya Katsuragawa

Prodigy 80 points

Part Number: LM7705

Hi team,

My customer is considering to use LM7705.

Could you answer for the question below?

Is there any possibility that the IC will not work by the wrong capacitance of the capacitor(C10)?

Could you tell me recommended capacity?

It is 0.1uF in the datasheet.

Regards,

Katsuragawa

over 4 years ago

0 Britta Ruelander over 4 years ago

TI__Genius 10860 points

Hi Katsuragawa-san,

we recommend the 0.1uF used in the datasheet. The capacitors at Vdd pin should prevent large variations of the supply voltage.

Best regards,

Britta

0 Naoya Katsuragawa over 4 years ago in reply to Britta Ruelander

TI__Prodigy 80 points

Hi Britta-san,

Thanks for the reply.

Is there any possibility that the IC will not work by the wrong capacitance of the capacitor(C10)?
why?

Best regards,

Katsuragawa

0 Britta Ruelander over 4 years ago in reply to Naoya Katsuragawa

TI__Genius 10860 points

Hi Katsuragawa-san,

are you asking because the 10uF and 0.1uF that is shown in the schematic above? For C10 you'r using the recommend 0.1uF for decoupling and for C9 10uF to guarantee a stable supply voltage, this is fine.

Can you share details in case you see an issue with the IC? For now I can only tell that the capacitances connected to Vdd are fine.

Best regards,

Britta

0 Naoya Katsuragawa over 4 years ago in reply to Britta Ruelander

TI__Prodigy 80 points

Hi, Britta-san,

I received a question from a customer.

Does the IC operate normally without the capacitor (C9)?

Because this customer wants to design it with a part as little as possible.

Could you give them some advice?

Best regards,

Katsuragawa

0 Britta Ruelander over 4 years ago in reply to Naoya Katsuragawa

TI__Genius 10860 points

Hi Katsuragawa-san,

thank you for your question.

In the datasheet we recommend adding a decoupling capacitor to avoid large variations on the Vdd pin (p.18, section 9). This capacitance is important as it prevents from spikes at the input, for example due to the on/off switching of the internal MOSFETs of the IC. Those spikes could damage the IC.

We can only guarantee functionality within the recommendations as this is what we test for.

Best regards,

Britta

0 Britta Ruelander over 4 years ago in reply to Britta Ruelander

TI__Genius 10860 points

Hi Katsuragawa-san,

please reply whether this thread can be closed.

As I didn't hear back from you I assume that your question as been answered already.

Thanks and best regards,

Britta

0 Naoya Katsuragawa over 4 years ago in reply to Britta Ruelander

TI__Prodigy 80 points

Hi Britta-san,

I'm glad to imform you that the problem is now solved.

Thank you.

Thanks and best regards,

Katsuragawa

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LM7705: C10 Capacitor - What is the best capacitance to keep IC from getting damaged?