LM2917N Description
The LM2917N is a monolithic frequency-to-voltage converter with a high gain op-amp designed to operate a relay, lamp, or another 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 (8-pin LM2907 and LM2917), and its output swings to the ground for a zero frequency input.
The LM2917N 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 50 mA. The collector may be taken above VCC up to a maximum VCE of 28 V.
LM2917N Features
Ground Referenced Tachometer Input Interfaces Directly With Variable Reluctance Magnetic Pickups
Op Amp Has Floating Transistor Output
50-mA Sink or Source to Operate Relays, Solenoids, Meters, or LEDs
Frequency Doubling For Low Ripple
Tachometer Has Built-In Hysteresis With Either Differential Input or Ground Referenced Input
+0.3% Linearity (Typical)
Ground-Referenced Tachometer is Fully Protected From Damage Due to Swings Above Vcc and Below Ground
LM2917N Applications
Speedometers
Over- and Under-Speed Sensing
Frequency-to-Voltage Conversion (Tachometer)
Speed Governors
Cruise Control
Breaker Point Dwell Meters
Hand-Held T tachometers
Automotive Door Lock Control
Clutch Control
Horm Control
Touch or Sound Switches
