I don't know if it's true, but I like the comment attribuited to Bob Pease: https://www.avrfreaks.net/forum/ultrasonic-sensors "National Semiconductors makes lots of good Op-Amps. The 324 isn't one of t= hem." I'd agree, it has "issues". -----Original Message----- From: piclist-bounces@mit.edu On Behalf Of Sean B= reheny Sent: Tuesday, July 10, 2018 9:09 AM To: Microcontroller discussion list - Public. Subject: Re: [EE] LM124 Slew Rate vs Temperature? (-55C to 125C) Hi Jason, Is there a reason for using such an ancient op-amp? This is part of the LM324 family which is only really ever used now in either ultra cost sensit= ive devices or legacy designs. Except for cost, there are many op-amps whic= h are better in every regard. I think you are right to be concerned. Slew rate depends on internal capaci= tances, resistances, and current magnitudes. All of those are temperature d= ependent AND manufacturing dependent. I would not be comfortable assuming t= his part can do 0.2V/us unless either the datasheet specified a minimum sle= w rate of more than that over all temperatures and manufacturing variation = OR if the typical value were at least 10x the necessary value (2V/us). Sean On Tue, Jul 10, 2018 at 10:29 AM, Jason White < whitewaterssoftwareinfo@gma= il.com> wrote: > In my current design the operating temperature range is rather large:=20 > -55C to 125C. > > I am planning on using the LM124DT from ST in an analog PWM circuit.=20 > My design uses a 0.5 to 4.5v triangle wave at 25kHz (required slew=20 > rate 0.2V/us). > > The LM124DT has a "typical" slew rate of 0.4V/us at 25C. A minimum=20 > slew rate is not specified and slew is not specified at other temperature= s. > Other manufacturers such as TI don't seem to specify this either. > > I would like to get an intuitive sense of how (or if) slew rate might=20 > change over temperature. Additionally I'd like to get some opinions as=20 > to whether 0.2V/us could be too fast for the LM124. > > Thanks, > Jason White > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20 > View/change your membership options at=20 > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .