[email protected] wrote:
The external voltage monitor solution should guard against a true
brownout or power loss. Sot 23 package size, low cost.
But if one tries to assert the reset with less than recommended
voltage, results are not guaranteed, I have proven that! ;,(
Note that other (more expensive?) msp430's have SVS - supply voltage
Its actually newer, rather than more expensive, parts which have the
brownout circuit. Originally a brownout circuit was left out because it
hurt the power consumption. The device was aimed at applications that
only reset once in 10 years, anyway :-) Someone finally came up with a
brownout design that takes very little power, and I think this will be a
standard element of all future MSP430s. The 1232 isn't expensive part,
and its in that.
Just how expensive/complex an external brownout circuit needs to be
depends a lot on what you are trying to achieve. Some applications have
to deal with a very slowly rising and falling supply line. Others need
to deal with supply spikes. Spikes are a pain, but a PNP transistor, a
zener, and a couple of resistors can deal with the slow rise and fall
problem quite effectively. There is a circuit for this in one of the TI
application notes, but if you think about it a little more you can do
better than that design. You might even be able to make it do the supply
regulation at the same time :-)
supervisor - built in. Others have found the same problem we have.
John Gilbert
Regards,
Steve
