3 Replies Latest reply on Jul 17, 2018 6:14 PM by xzng

PSoC63 BOD not guaranteed in Hibernate Mode

andre.vaas_2417461 Jul 12, 2018 8:47 AM

Hello,

in the TRM of the PSoC63 on page 130 I read the following:

- The brownout detect (BOD) block is not available in Hibernate mode. As a result, the device does not recover from a brownout event in Hibernate mode. Do not enter Hibernate mode in applications that require brownout detection, that is, applications where the supply is not stable.

In our application we can not guarantee a stable power source, so it is possible that the voltage drops below the the BOD voltage and then ramps up again. As it is a low power application, we must use the Hibernate mode.

Question: What could happen if the device is in Hibernate mode and the voltage drops below BOD and rises again? Could the chip get stuck and does not recover / reboot itself? Is the only solution to add an external super visor IC to the reset pin?

Thank you!

Regards

Andre

1. Re: PSoC63 BOD not guaranteed in Hibernate Mode

msur Jul 12, 2018 9:50 AM (in response to andre.vaas_2417461)

Andre,

To your questions -
1. The device may or may not be able to recover, as the hibernate circuits may not be reset (BOD) and can result in corruption and impact the behavior. Hence it is advised to turn off Hibernate if the power supply is not stable.
2. It would be better to add an external supervisor, if low (hibernate level) power is desired.

Regards,
Meenakshi Sundaram R
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2. Re: PSoC63 BOD not guaranteed in Hibernate Mode

andre.vaas_2417461 Jul 13, 2018 1:50 AM (in response to msur)

Thanks for your answer! I have another idea:

Can I use the low power comparator to measure the supply voltage and if it drops below 1.8 V then the comparator will wake up the system from Hibernate with an reset and the BOR will be activated again?

Thank you!
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3. Re: PSoC63 BOD not guaranteed in Hibernate Mode

xzng Jul 17, 2018 6:14 PM (in response to andre.vaas_2417461)

It is theoretically feasible, but it is not easy to operate actually。For example, how do you ensure that the comparison value does not change when voltage drop? How to choose the pre-capacitor to ensure that the chip can continue to wake up and work during the power-down process, etc.
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