??? 06/26/09 09:34 Read: times |
#166482 - Erik, brown-out is handled by Silabs MCU!! Responding to: ???'s previous message |
I went through the datasheet again, and got some interesting facts
1. VDD monitor always kicks in when the MCU is powered on. It keeps the chip in reset till the supply voltage reaches 2.7 volts, which is the minimum voltage required for the core to operate. After the supply reaches 2.7 volts 0.3 ms delay is inserted and the reset is released. 2. After power on reset, you need to enable VDD monitoring to manage brown outs. If VDD monitoring is on, the monitor circuits keeps the chip in reset, regardless of the status of reset pin, since the reset pin is just one the the inputs that get or-ed to generate reset pulse. These two features above should take cover the supply-monitoring-and-resetting feature of a supervisory chip, shouldn't they? Is the sole reason behind the latch-up the fact that the reset alone is not sufficient for the chip? As Daniel was suggesting, even if the reset is held low till the VDD reached the right voltage (which is what the supervisory chip does, and nothing more than that), it may not be sufficient since some other part of the MCU which do not get reset by the reset circuitry (?) wouldn't have got started ?? Just thinking loud hoping to get some clarification from you guys.. |