MSP430F5638 hangs upon powering up. Looking for power up order tips/things that should be checked

Hi Jeff,

Do you have the recommended pull-up/cap values for RST, VCore, VBAT, VBAK and all USB circuitry?
Compare the values vs the datasheet, or with a board like MSP-TS430PZ100USB.

Have you checked erratum USB9?

Also, does this behavior happen when the board is completely without power even in GPIOs? GPIOs have a protection diode which can provide power to the MCU even when DVCC is off.

Regards,
Luis R

It has only happened a few times and I haven't been able to replicate it so I'm not exactly sure why it happened yet but I don't want the design to do it in the field so double checking. Looking at the recommended operating conditions: VBAK, VCORE are good. Why do they state the Capacitor ratio of DVCC to VCORE as a min of 10? Are they saying put a 4.7uF on DVCC1 if VCORE is at 470 nF

It is also curious that AVCC1 isn't listed in that section with a recommended cap.

Some notes to RST;

An unstable Vcc at Boot can lead to an incomplete initialization of the device Hardware.

Verify you have (at least) a 4.7uF low ESR (ceramic) capacitor at Vcc. If Vcore is applicable and having a capacitor connected to Vcore, the capacitor at Vcc must be at least 10 times bigger then the capacitor at Vcore, this to be able to (nearly) fully charge the Vcore capacitor.

If you have the default RST setup, 2.2nF + 47K, then increase the capacitor to 10nF or higher to ‘debounce’ Vcc by lengthening POR. And if you still want to be able to flash the device (and a RST cycle is needed) with MSP-FET, add a series resistor of 1K with the capacitor.

Using a 'slow' starting power-supply or if you need to charge a 'super-cap’, a longer reset time is needed, and to at least Vcc exceeds the voltage level needed to start the MCU (~1.2V). This can be best realized with a "Supply Voltage Supervisor".

Additional you can add a start-up delay at the begin of your software, to prevent enabling modules with intensive use of power at boot.

Hi Jeff,

I'm closing this thread due to lack of activity, but please feel free to let us know if you have any further comments or questions

Regards,
Luis R

Understand. Our new design is due back this week so I will be able to test and report back soon. I hope we fixed it.