At 14.41 2008.05.28, you wrote: >Quoting Electron : > >> At 13.16 2008.05.28, you wrote: >>> At 07:02 AM 5/28/2008, you wrote: >>> >>>> Hello, >>>> >>>> It looks like there's no suitable 5V Transil/Tranzorb when you >>>> want to protect >>>> a circuit that has to sleep most of the time (say draw no more than >>>> few uA's on >>>> its own when sleeping). >>> >>> You need to protect what (input, output, power supply?) , against >>> what (voltage, available current) , exactly? >> >> Power to several expensive and delicate +5V IC's. > >Can you use a micropower LDO and then use the Tranzorb to protect >the LDO? That gives you a lot of headroom for the Tranzorb to go from >negligible current to massive current. Actually I need to protect the rest of the circuit from the LDO itself. ;) >> I already had a voltage regulator fail because of a stupid hardware >> bug of one >> of the above IC's, which made it draw around 190mA in some particular moments >> (bug then acknoledged in the errata): the TPS71550 voltage regulator >> fried and >> passed +20V to the rest of the board, frying everything. > >Ouch. I'm sure you've tried to prevent *that* from happening again. That's what I'm trying to do. :P >Although usually the costs of a field failure dwarf the cost of most >ICs unless you're talking about a $200 FPGA or big CCD or something like >that, in which case I'd be thinking a bit about some kind of crowbar >arrangement, depending on the total cost. With some loads such as a >$250,000 "black box" you want to not only ask the voltage regulator nicely >to shut down, but do things that give it absolutely no choice. Oh yes, a crowbar, why haven't I thought of it? A comparator plus a small SCR, and a fuse to blow.. problem solved. Thank you. :) > > >Best regards, >Spehro Pefhany >-- >"it's the network..." "The Journey is the reward" >s...@interlog.com Info for manufacturers: http://www.trexon.com >Embedded software/hardware/analog Info for designers: http://www.speff.com > > >-- >http://www.piclist.com PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist