saiello
New Member
Hi All,
I'm using the LM311 voltage comparator in my circuit. Everything works great but I came across a slight anomaly. +ve supply to the 311 is 5V, -ve supply 0V. The +ve ref voltage is selected with a potentiometer ranging within 0V-5V and the -ve input voltage automatically ranges from 0V-5V. All standard stuff. From reading the datasheets and the numerous circuits on the net utilising the 311, I was under the impression that the input and ref voltages can be anything between the -ve and +ve supply voltages and the 311 will operate as specified. What I found was that when I set the ref voltage to below about 3.9V, the 311 will happily switch it's output when the input rises above 3.9V. When the ref voltage is set above this, to say 4.0V, any amount of input voltage will not switch the output. I cannot find any information in the datasheet or on the internet about this. Is this normal or have I blown the 311?
Thanks!
I'm using the LM311 voltage comparator in my circuit. Everything works great but I came across a slight anomaly. +ve supply to the 311 is 5V, -ve supply 0V. The +ve ref voltage is selected with a potentiometer ranging within 0V-5V and the -ve input voltage automatically ranges from 0V-5V. All standard stuff. From reading the datasheets and the numerous circuits on the net utilising the 311, I was under the impression that the input and ref voltages can be anything between the -ve and +ve supply voltages and the 311 will operate as specified. What I found was that when I set the ref voltage to below about 3.9V, the 311 will happily switch it's output when the input rises above 3.9V. When the ref voltage is set above this, to say 4.0V, any amount of input voltage will not switch the output. I cannot find any information in the datasheet or on the internet about this. Is this normal or have I blown the 311?
Thanks!