1. Home
  2. Electronics Design
  3. LM358 strange behavior !
  4. Page 2

LM358 strange behavior !

*If* there's no latchup hazard in the opamp. I never pull below ground any pin on those ancient National designs. 
--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation
Reply to
John Larkin
Loading thread data ...

:
81R

er

That's not a hazard, it's a feature--crowbar. LM34, right?

Grins, James

Reply to
dagmargoodboat

Exactly! I like Phil because his knowledge exceeds Jamie's (Maynard's) by several orders of magnitude and he communicates it clearly. I have learned much from him and I suggest Jamie try to do the same.

Reply to
John S

Well, no wonder that you never learn anything. He is a prolific poster here and provides great information.

Maybe you got some infatuation

Infatuation? Is that your practice word of the day?

I must ask, what is a sit in a stooly? I don't think I've ever done anything like that. It must be something with which you are familiar and I am not.

Well, I've already replied that I would rather learn from Phil than see your junk.

Reply to
John S

I never pull below ground any pin on those ancient National designs.

More's the pity.

--
JF
Reply to
John Fields

Why? Do you enjoy chips doing weird things, latching up?

If you're not 100% sure where substrate current is going to go, pulling pins below ground is hazardous. LM324, LM339, 4000A cmos, LM35, lots of ADCs and DACS, were notorious. Lots of new designs still have latchup problems; it must be very hard to fix, since so many designs have this hazard.

When you put hundreds, sometimes 1000+ parts on a board, you've got to be paranoid about risk, or it will never work.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation
Reply to
John Larkin

Yes. Read the tiny footnotes, and never power them from more than 5 volts.

We're using LM50's lately, because you can pull down to ground safely and still measure -40C.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation
Reply to
John Larkin 

--
Whoosh!!! 

.            +--------+ 
.            |  +V    | 
.            |   |   [R] 
.Vin>---[R]--+--|-\   | 
.               |  >--+-->-Vin 
.           +---|+/ 
.           |    | 
.          GND  -V
Reply to
John Fields

I meant, obviously, pulling a signal pin of a single-supply chip below its substrate ground.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation
Reply to
John Larkin

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.