Integrated Circuits LM2917 Frequency to Voltage Converter Z2640

LM2917 Frequency to Voltage Converter

The LM2917 is a monolithic frequency to voltage converter with a high gain op amp/comparator designed to switch 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 as the output swings to ground for a zero frequency input.

Features

• Ground referenced tachometer input connects directly to variable reluctance magnetic pickups
• Op amp/comparator has floating transistor output
• 50 mA sink or source to switch relays, solenoids, meters, or LEDs
• Frequency doubling for low ripple
• Tachometer has built-in hysteresis with a choice of differential input or ground referenced input
• Built-in zener
• +/-0.3% linearity typical
• Ground referenced tachometer is fully protected from swings above VCC and below ground

Advantages
Output swings to ground for zero frequency input
Simple to use VOUT = freq.IN x VCC x R1 x C1
Only one RC network provides frequency doubling
Zener regulator on chip allows accurate and stable frequency to voltage or current conversion

Applications
Over/under speed sensing
Frequency to voltage conversion (tachometer)
Speedometers
Breaker point dwell meters
Hand-held tachometer
Speed governors
Cruise control
Automotive door lock control
Clutch control
Horn control
Y Touch or sound switches