[SOLVED] Common mode voltage range of opamp

[kamalavignesh]

Hi,
why the common mode voltage range of opamp is limited to very small value in negative side(lower end). For example the common mode voltage range of lm324 is -0.3V to 36V.
In positive side the range is more but in negative side the range is less. Why the opamp was designed like that? suppose if i want to give -0.5V as common mode input what i have to do? Any opamp is available in the market having the common mode range -0.5V to 36V.

 

[ckshivaram]

check if this helps
Operational amplifier - encyclopedia article - Citizendium
**broken link removed**
https://focus.ti.com/lit/ds/symlink/ths4521-ht.pdf

 

[Orson Cart]

for single supply op amps like the LM324 you are lucky because you can go -0.3v below gnd on the single supply to the opamp.

for any opamp with a split supply e.g. 0+/- 15V then the CM range will be -14.x to +14.x, for the LM324 it will be -15.3 to 14V ,

Regards, Orson Cart.

 

[kamalavignesh]

Thanks for the inputs.