| ??? 03/07/07 21:03 Read: times |
#134545 - it takes more than a supervisor Responding to: ???'s previous message |
Erik Malund said:
For most managers, it's hard to justify a $4 reset/power management circuit for a $1 MCU
a simple supervisor such as the TPS3809I50DBVT cost $0.39 and that is just at qty 250, I can imagine the price at qty 1,000,000 (even cheap) Modern uCs have the watchdog (a digital circuit) built in so, if you want the puppy (many volume makers do not) you do not need to go for a 1232 or such. Erik So, you're saying that TPS3809I50DBVT is what you think people should use to avoid the flash corruption and other anomalies? I wasn't referring to a $0.39 supervisor, but, rather, a circuit that would manage the power and the oscillator, as well as generating a "real" reset and not just the "NMI" to which Lynn referred as well as doing that when needed, and would pull down the MCU power when a the power was dropped. I figured that a cheap supervisor plus a CPLD, plus a couple of small bipolar transistors and maybe a FET would do the job. There's a fair amount of timing and gating that's required in order to sequence the power and reset correctly, isn't there? ... particularly if you want to pull down the MCU power once you've determined that board power is being lost. RE |
