The LM2917M/NOPB is a monolithic Frequency-to-voltage Converter with a high gain op amp/comparator designed to operate a relay, lamp or other load when the input frequency reaches or exceeds a selected rate. The tachometer uses a charge pump technique and offers frequency doubling for low ripple, full input protection in two versions (LM2907-8, LM2917-8) and its output swings to ground for a zero frequency input. The op amp/comparator is fully compatible with the tachometer and has a floating transistor as its output. This feature allows either a ground or supply referred load of up to 50mA. The collector may be taken above VCC up to a maximum VCE of 28V. The two basic configurations offered include a 8-pin device with an input and an internal connection between the tachometer output and the op amp non-inverting input. This version is well suited for single speed or frequency switching or fully buffered frequency to voltage conversion applications.
Ground referenced tachometer input interfaces directly with variable reluctance magnetic pickups
Op amp/comparator has floating transistor output
Frequency doubling for low ripple
Tachometer has built-in hysteresis with either differential input or ground referenced input
Built-in zener on LM2917
±0.3% Linearity typical
Ground referenced tachometer is fully protected from damage due to swings above VCC & below ground