SLOA277B january 2019 – july 2023 LM124 , LM124-N , LM124A , LM158 , LM158-N , LM158A , LM224 , LM224-N , LM224A , LM258 , LM258-N , LM258A , LM2902 , LM2902-N , LM2902-Q1 , LM2902K , LM2902KAV , LM2904 , LM2904-N , LM2904-Q1 , LM2904B , LM2904B-Q1 , LM2904BA , LM321 , LM324 , LM324-N , LM324A , LM358 , LM358-N , LM358A , LM358B , LM358BA , TS321 , TS321-Q1
When using an op amp as a comparator, the key DC parameters to consider are input offset voltage, input common mode range, low output voltage (VOL) and high output voltage (VOH). It is important to maintain a valid input common mode, otherwise phase reversal may occur as discussed earlier in this document. When used in a comparator application, the input common mode voltage of the op amp will be the same as the least positive input voltage. For example, if one input is 2 V and the other input is 3 V, the common mode voltage would be 2 V. The voltage of the other, higher voltage input doesn’t affect the input common mode voltage in this device family and many other PNP and PMOS op amp families.