LM2917N/NOPB

The LM2917N/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