OPAMP Voltage Follower for ADC

[SBTECH]

Hi ,

I am reading a temp sensor data between 0-10Volts with an ADC capable of reading 0-2.5V.

So I made a voltage divider and a voltage follower with lm 324 opamp which is sourced by 9V single supply. I am not experienced about analog circuits and i made this test circuit in the attachment .

When i connect no loads to the output i measure 0 volts , when i connect 120 ohm to the output through ground i measured 0.55 V on the output. I measure 2.25 volts between non inverting input and ground. but at the common point (output and inverting input point ) to the ground i dont measure the same voltage. It must be same according to theory of opams.


I tried to put 5 ohms and my opamp overheated itself , now no matter i connect anything to its inputs or outputs,when i just power it with 9V it overheats itself , i think its broken now.

So what should i do to make this voltage follower work . I always had so many problems with opamps , i wanna solve my problems with them this time.. Could you share ideas to make this voltage follower work ?

Many thanks ..

 

[FvM]

LM324 is specified to source >20 mA, so it should be able to drive 2.25V into 120 ohm, but surely not 5 ohm. It shouldn't be damaged by shorting a single output according to the datasheet. The reported behaviour isn't understandable from the datasheet. Either the device has been damaged or there are other unsaid circuit problems.

 

[SBTECH]

Thank you , I think my problem was due to something wrong with my chip or my pcb. I just made the circuit on breadboard with a new chip it seems like working nice.

Are you talking about Output Current Source value written in the datasheet when you are implying >20mA . Also In other circuit I am using 2.25 volts as buffer again and in the output of the OPAMP I have a 5K potentiometer to create a reference voltage between 0 and 2.5 volts for my microcontroller ADC . But When I drive 2.25 volts through buffer my ADC reference voltage changes between 0.3 and 1.8V while I was trying adjust with pot. ? Is there any way to make this work between zero and 2.25 volts ?

Understanding the datasheet values are really hard for me , do you know any wiki source or something about this issue ?

FvM, Thank you very much for your glance at my circuit !!

 

[SBTECH]

It has been a while,but the problem about my circuit was due to the OPAMP. I changed the chip with a new one and everything worked fine