This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

  • Resolved

MSP430F5338: RTC working time when powered using Super Capacitor only

Prodigy 85 points

Replies: 3

Views: 238

Part Number: MSP430F5338

Hi,.

  We are designing a system in which MSP430F5338 is used.

  For powering the RTC in the MSP430 during shutdown, we have used a 3.5V 0.22uF super capacitor connected to VBAT.

  The question is that, how long will the super cap alone be able to supply power for RTC to work?

  Or, how can we determine the duration for the which the RTC is working with super cap alone connected?

 Thank you.

  • Hello Veeramani,

    The current consumption of the MSP430F5338 can be found in the datasheet(section 5.5). Also, note the minimum operational voltage in section 5.2 as the supercap will discharge fairly linearly and you will need to know when the MSP430 cannot operate any more. Also, I found a handy calculator tool to help calculate the discharge time.

    www.circuits.dk/calculator_capacitor_discharge.htm

    Best Regards,

    Eddie

    Don't forget to verify answers to your forum questions by using the  Verify Answer  button.

  • In reply to Eddie LaCost:

    Hi Eddie,
    Thanks for the reply
    According to the section 5.2 the minimum operational voltage is 1.70V
    So, if I am testing it practically, and I get a different result, Which result should I consider?
  • In reply to VEERAMANI VISWANATHAN B:

    I would go with the datasheet value.  I am assuming that you have observed it can actually operate at a lower voltage.  It is possible that our devices can operate outside of the specification, especially at lower clock rates, but this is not guaranteed and could vary from device to device.  The minimum datasheet specification should be applicable to all devices we ship.

    Best Regards,

    Eddie

    Don't forget to verify answers to your forum questions by using the  Verify Answer  button.

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.