In a PM, wireengineer wrote:
***********************************************************
Hi JimB. Thanks for all the replies on the following link...
12v battery monitor circuit help!!!!
I was just wondering if you could help me' with one more thing. Could you please explain to me' the theory of operation behind the circuit?
Thankyou!
***********************************************************
I prefer to answer in the forum, then others can benefit from the information.
First, have a look at the datasheet:
https://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1002,C1463,P1172,D2764
Second, the LTC1440 works by comparing the voltage at pin3 with the voltage at pin4.
When the pin3 is a higher voltage than pin4, the putput at pin8 is high , when pin3 is at a lower voltage than pin4, the output at pin8 is low.
The voltage at pin4 is the reference voltage form the zener, the voltage at pin 3 is the supply voltage divided by the potentiometer R1/R2.
JimB