Part Number:CC2640
I'm seeing what seems to be a failure in the BOD circuit on the CC2640.
On our custom board, the VDD voltage drops from 3.3 volts to around 1.6 and an event does occur. However, it doesn't seem like a reset is generated.
The chip does not restart execution, but seems to be stuck in a cycle, the voltage rising to 1.9 very quickly, then gradually dropping to about 1.6 volts, then repeats this cycle endlessly.
The GPIOs never get tri-stated. It's as if a brown out is detected, but a reset is never generated.
The behavior that causes this failing condition is as follows:
When power is first applied to the VDD input of the CC2640 it rises within a few hundred microseconds to 3.3 volts. Then, the voltage drops very gradually from 3.3 volt down to 1.6 volts over a period of roughly 45 seconds.
Could it be that the BOD circuit does not function correctly if deltaV / deltaT is low while the voltage crosses the BOD threshold?
Is there a spec for how long the reset is asserted?
When the reset is asserted, is it supposed to get propagated externally on the resetn pin?
John