26th January 2005, 08:55 #1
Member level 3
I want to use LM324 as an comparator . My bro told me should use LM339 but
I don't know the difference among them . The 339 looks similar the 324 (but 339 is open colector ) . I should use 339 in which work and 324 in which work ??
26th January 2005, 08:55
26th January 2005, 10:47 #2
Junior Member level 2
lm324 vs lm339
LM324 has wider bandwidth (1MHz). if u want to use it in an ordinary app, LM339 is quite good choice. sometimes to use faster comparator need more task for stabilization.
application note AN-74 from National Semiconductor can help u about LM339
if u want to use a high speed comp, LB-39 from national semiconductor is useful.
26th January 2005, 10:47
28th January 2005, 21:27 #3
Member level 2
lm324 as comparator
The LM339 is designed specifically as a comparitor. The LM324 is a general purpose opamp which can be used as a comparitor. I would use the LM339 with a pullup resistor. Also if you need a window comparitor you can join the 2 outputs together because they are open collector (ie AND gate).
28th January 2005, 21:27
28th January 2005, 21:33 #4
Full Member level 4
I would propose that you switch to TL074.
It is probably cheaper than LM324 and offers many advantages. Lower offset, output short circuit protection, etc...
I have also successfully used it as comparator and output driver for 50 ohms load (it doesn't give very high output voltage but it is still usefull....).
29th January 2005, 02:11 #5
Advanced Member level 5
lm339 vs lm324
Generally speakng 339 is not very precise comparator with average response time, so you can easily use 324 instead. The only difference will be that you can connect its output to larger voltages then its supply because of the OC output stage.
On the other hand, you can not replace 324 with 339 in linear applcations because 329 as comparator has only Low or High as the output stages..