The FAN7544M from Fairchild Semiconductor is a fluorescent light ballast controller Integrated Circuit operating at 48.2 to 57.8 kHz, in an 8-SOIC package, with the attribute No.
The FAN7544MX from onsemi is a lighting ballast controller Integrated Circuit operating at 48.2 to 57.8 kHz, with the attribute No, in an 8-SOIC package.
The FAN7544MX from Fairchild Semiconductor is a fluorescent light ballast controller operating at 48.2 to 57.8 kHz, with No (unlisted option) as given, in an 8-SOIC package.