LM2917MX

LM2907 / LM2917频率电压转换器 LM2907/LM2917 Frequency to Voltage Converter

General Description

The LM2907, LM2917 series are monolithic frequency to voltage converters 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 50 mA. The collector may be taken above VCC up to a maximum VCE of 28V.

Advantages

Output swings to ground for zero frequency input

Easy to use; VOUT = fIN 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 LM2917

Features

Ground referenced tachometer input interfaces directly with variable reluctance magnetic pickups

Op amp/comparator 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

Built-in zener on LM2917

±0.3% linearity typical

Ground referenced tachometer is fully protected from damage due to swings above VCC and below ground

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

Touch or sound switches