Newsgroups: sci.electronicsPath: cantaloupe.srv.cs.cmu.edu!crabapple.srv.cs.cmu.edu!bb3.andrew.cmu.edu!news.sei.cmu.edu!cis.ohio-state.edu!zaphod.mps.ohio-state.edu!cs.utexas.edu!utnut!utzoo!henryFrom: henry@zoo.toronto.edu (Henry Spencer)Subject: Re: HELP: MC146818A Real Time Clock Standby ModeMessage-ID: <C5uCDu.1Ip@zoo.toronto.edu>Date: Wed, 21 Apr 1993 15:58:40 GMTReferences: <1r0b69INN5ct@flash.pax.tpa.com.au>Organization: U of Toronto ZoologyLines: 20In article <1r0b69INN5ct@flash.pax.tpa.com.au> mgregory@flash.pax.tpa.com.au (Martin John Gregory) writes:>I am having trouble obtaining the specified standby current drain from>a MC146818A Real Time Clock...>lowest current drain I can acheive at 3.7V Vcc is 150uA.  This is>three times the specified MAXIMUM...>1) Made sure that RESET/ is asserted for Trlh after powerup, and AS is>   low during this time.>2) Made sure that there is a cycle on AS after the negation of RD/ or>   WR/ during which STBY/ was asserted...Are any of the inputs to the chip coming from TTL?  Standby-drain specsfor CMOS chips typically apply only if inputs are pulled all the way downto zero or all the way up to Vcc.  TTL isn't good at doing the former andit won't do the latter at all without help from pullup resistors.  Thissort of thing can easily multiply power consumption by a considerablefactor, because the CMOS transistors that are supposed to be OFF aren'tall the way hard OFF.-- All work is one man's work.             | Henry Spencer @ U of Toronto Zoology                    - Kipling           |  henry@zoo.toronto.edu  utzoo!henry