MAX232: Selection of the capacitors

Placido Romano

Part Number: MAX232

I have an old circuit in production on the while is mounted a RS232 driver with capacitors 10uF tantalium. Now I'd like change the IC driver with MAX232 but the pump capacitor is 1uF. Is not possible change the IC without change the capacitors?

Does someone suggest me?

Thanks

Placido

over 5 years ago

0 Eric Schott1 over 5 years ago

TI__Mastermind 48135 points

Hi Placido,

Using larger flying capacitors will result in a larger ripple noise at the charge pumps output as the device will take longer to switch (longer charge times). Though 1uF would be optimal, the device should still be able to function with 10uF capacitors connected. I would recommended testing this configuration with the rest of your system to ensure the added noise does not effect communications.

Also, please ensure the polarized capacitors are facing the correct direction in your layout:

Let me know if you have any more questions.

Regards,

Eric

0 Placido Romano over 5 years ago in reply to Eric Schott1

Prodigy 20 points

Thank you Eric.
The communication works at low baud rate. I will do some tests at high baud and I will inform you about the tests.
Regards

0 Max Robertson over 5 years ago in reply to Placido Romano

TI__Guru 62910 points

Hi Placido,

I just wanted to follow up on this. Did you find that the device was working well at the higher baud rates, or did you encounter any issues?

Regards,
Max

0 Max Robertson over 5 years ago in reply to Max Robertson

TI__Guru 62910 points

Hi Placido,

Do you have any updates on this? Or, is there any other help we can provide?

Regards,
Max

Interface

Interface forum

MAX232: Selection of the capacitors