Hi,
One customer met a MSP430F5525 PUR BSL issue. The customer used MSP430F5525 in the project, for not using USB funciton and according to MSP-EXP430F5529 experimenter board schematics and MSP430x5xx/MSP430x6xx family user's guide, the customer connected PUR pin with Dvss with a 1M Ohm resistor, connected VBUS pin with Dvss with a 47k Ohm resistor, to confirm PUR and VBUS pin's voltage should be 0V after power on. The devices has been produced more than 30k totally, but 3 devices met the issue that can't start up normally after power on, I checked several pins' voltage, VCC pin voltage was about 2.90V, Vcore pin voltage was about 1.93V, /RST pin voltage was about 2.90V, PUR pin voltage was not 0V but 2.0V, so according to the F55xx USB BSL function, the failure devices must be entered into BSL mode after power on, right? After re-power on, the PUR pin voltage was recovered to 0V and the failure disappeared and can't reproduce, so this action verified my guessing.
In my idea, if connenct a 1M Ohm resistor between PUR pin with Dvss, the PUR pin voltage should always be 0V and the device should not enter BSL mode, right? Is there some in-chip circuit root reason?
BTW, I have posted a similar topic before, pls refer to it from below link.