Voltage Detector / MCU Supervisors? Are They Really Necessary?

[CocaColaKid]

Just curious if the on-board brown-out detection and power-on timer is enough protection or should I continue to use them. All my prototypes run with just a resistor pulled to the rail with no issues however all our production units use them. I'm just wondering if they are really worth the extra $$.

[mister_e]

Few of my product have MCU supervisor and some no. After few years on the market, none seems to be better than another.

[Acetronics2]

Hi, CCK

External reset circuits are useful when you do not want to reset at the voltage given by the Brownout ... ( batt powered devices i.e. )

or if there is no brownout on the device !!!...

They may also be useful if you want particular power-on timings for peripherals ...

one other evident use is NOT to reset the processor, but enter a failsafe section on lowbatts ... with reset circuit connected to an " ordinary " pin !!!

MC 33x64 devices are great for that !!!

Alain

[Melanie]

Most of my designs have MCLR (on those PICs that need it) strapped straight to Vdd... don't bother with any Resistor. By the end of this year I'll have had over a million PICs shipped... never any problems...

The only time I'd consider a supervisory chip is in a life or death situation... eg elevator control (or my coffee maker)...

[CocaColaKid]

Thanks for the replies guys and gal. I guess my next run of boards I will lose this added expense.