ELM440

ELM440 60Hz Generator Description The ELM440 is an 8 pin digital divider integrated circuit, that provides both 60Hz and 1Hz outputs from a common 3.58MHz NTSC colourburst crystal. Externally, the designer need only provide the crystal and two appropriate loading capacitors, as well as a suitably bypassed power supply. Internal oscillator circuits then use this reference frequency to precisely derive a stable 60Hz signal. This signal is then further divided to provide a 1Hz output. The ELM440 can also be locked in synchronism to an external 60 or 120 Hz line frequency signal. If derived from the electrical grid voltage, this results in excellent long-term stability, as the power generation frequency is traceable to national standards. The transition to or from sync-lock with this external signal occurs automatically. A reset input is also provided to restart the internal counters, if desired. An active low signal on this pin will force both outputs to an open or tristate condition. Features Low power CMOS design Wide supply range - 3.0 to 5.5 volt operation Generates both 60Hz and 1Hz references Automatically synchronizes to the line frequency for long term stability, when it’s available Uses a standard 3.58MHz crystal for the time reference if there is no sync input High current drive outputs - up to 25 mA Connection Diagram PDIP and SOIC (top view) VDD XT1 XT2 reset 1 2 3 4 8 7 6 5 VSS 60Hz 1Hz sync Applications Stable 60Hz and 1Hz reference sources M...