Latching Comparator

Thread Starter

mshalash

Joined Dec 27, 2012
13
Hi All
Latch Comparator
Kindly advise on this problem
I am trying to implement a circuit to shut down power using LM311 comparator and P-Mosfet
but getting nowhere.
see the schematic attached.
Thanks
 

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Alec_t

Joined Sep 17, 2013
12,897
Welcome to AAC!
Do you want to shut down power when the input signal goes above Vref or below Vref?
Will the comparator still have its power supply after shut down has occurred?
 

ericgibbs

Joined Jan 29, 2010
15,726
hi m,
This is a circuit for LTSpice from your image.
We need to know the voltage levels.
E

Added 2nd Plot with PMOSFET
EG 1653.gif
 

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Last edited:

Thread Starter

mshalash

Joined Dec 27, 2012
13
hi msh,
Welcome to AAC.
What are the voltage levels on your circuit.?
E
Thanks for your response
it is 7 to 8.4 v (2 x LI-On batteries 3.7v each in series) and the signal should be less than the V ref (1.24V) above which should cut off and latch
 

Thread Starter

mshalash

Joined Dec 27, 2012
13
Welcome to AAC!
Do you want to shut down power when the input signal goes above Vref or below Vref?
Will the comparator still have its power supply after shut down has occurred?
SHut down above V ref (1.24v) and LM311 will still have power after shutting down +v on load only
 

ericgibbs

Joined Jan 29, 2010
15,726
hi m,
It works as your initial post, a circuit to shut down power using LM311 comparator and P-Mosfet

Please define what you mean as latching, I need a little more information.

E
 

Thread Starter

mshalash

Joined Dec 27, 2012
13
hi m,
It works as your initial post, a circuit to shut down power using LM311 comparator and P-Mosfet

Please define what you mean as latching, I need a little more information.

E
I mean it shuts the load +ve when the signal goes above V ref and keeps it shut even when the signal goes down to less than V Ref
 

ericgibbs

Joined Jan 29, 2010
15,726
I mean it shuts the load +ve when the signal goes above V ref and keeps it shut even when the signal goes down to less than V Ref
hi m,
The circuit I posted was not designed to remain shut when the Vsignal falls below 1.24V
E
 
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