TPA3221: BST capacitors

Kenji Ohno1

Genius 5095 points

Part Number: TPA3221

Hi Team,

Can I change the recommended capacitor "33nF / 50V X7R BST capacitors are recommended."

As 33nF capacitors take a lot of time to obtain, my customers are looking for alternatives.

If it is 22nF or 47nF, it is good availability, so I would like to change it to either. Which one is recommended?

Best Regards,

Kenji

over 6 years ago

0 Shawn Zheng over 6 years ago

TI__Mastermind 24835 points

Hi Ohno-san,
We need to know more info about this application, e.g. power supply voltage, load resistance, output power...
Best regards,
Shawn Zheng

0 Kenji Ohno1 over 6 years ago in reply to Shawn Zheng

Genius 5095 points

Hi Shawn-san,

Thank you for your early reply.
I would like to know is the output power side.

Regards,
Kenji

0 Kenji Ohno1 over 6 years ago in reply to Kenji Ohno1

Genius 5095 points

Hi Shawn-san,

I'm waiting for your reply.
Can you give me good information?

Best Regards,
Kenji

0 Justin Bohr over 6 years ago in reply to Kenji Ohno1

TI__Mastermind 28020 points

Hi Kenji,

Let me look into this and I will get back to you tomorrow.

Justin

0 Justin Bohr over 6 years ago in reply to Justin Bohr

TI__Mastermind 28020 points

Hi Kenji,

The risk of going lower in capacitance is that there will not be enough charge stored in the capacitor to reliably enable the FET to switch, and going larger may have some performance/efficiency impacts, but might be minor. To be safe I would go for the 47nF caps, but 22nF may also work as well.

Another option is using a lower rated 33nF cap, if that is easier to find. The BST cap will only see the GVDD voltage across itself so using a 16V or 25V rated cap should be fine.

Justin

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TPA3221: BST capacitors