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LM2907 LM2917 Frequency to Voltage Converter

February 1995

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 andoffers 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


Frequency doubling for low ripple Tachometer has built-in hysteresis with either differential input or ground referenced input Built-in zener on LM2917 g 0 3% linearity typical Ground referenced tachometer is fully protected fromdamage due to swings above VCC and below ground



Output swings to ground for zero frequency input Easy to use VOUT e fIN c VCC c R1 c C1 Only one RC network provides frequency doubling Zener regulator on chip allows accurate and stable frequency to voltage or current conversion (LM2917)



Ground referencedtachometer 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

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 Horncontrol Touch or sound switches

Block and Connection Diagrams Dual-In-Line and Small Outline Packages

Top Views

TL H 7942 – 1

TL H 7942 – 2

Order Number LM2907M-8 or LM2907N-8 See NS Package Number M08A or N08E

Order Number LM2917M-8 or LM2917N-8 See NS Package Number M08A or N08E

TL H 7942 – 3

TL H 7942 – 4

Order Number LM2907N See NS Package Number N14A
C1995National Semiconductor Corporation TL H 7942

Order Number LM2917M or LM2917N See NS Package Number M14A or N14A
RRD-B30M115 Printed in U S A

Absolute Maximum Ratings (Note 1)
If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Supply Voltage Supply Current (Zener Options) Collector VoltageDifferential Input Voltage Tachometer Op Amp Comparator Input Voltage Range Tachometer LM2907-8 LM2917-8 LM2907 LM2917 Op Amp Comparator 28V 25 mA 28V 28V 28V
g 28V 0 0V to a 28V 0 0V to a 28V

Power Dissipation LM2907-8 LM2917-8 LM2907-14 LM2917-14 (See Note 1) Operating Temperature Range Storage Temperature Range Soldering Information Dual-In-Line Package Soldering (10 seconds) Small OutlinePackage Vapor Phase (60 seconds) Infrared (15 seconds)

1200 mW 1580 mW
b 40 C to a 85 C b 65 C to a 150 C

260 C

215 C 220 C See AN-450 ‘‘Surface Mounting Methods and Their Effect on Product Reliability’’ for other methods of soldering surface mount devices

Electrical Characteristics VCC e 12 VDC
Symbol TACHOMETER Input Thresholds Hysteresis Offset Voltage LM2907 LM2917 LM2907-8LM2917-8 Input Bias Current VOH VOL I2 I3 I3 K Pin 2 Pin 2 Output Current Leakage Current Gain Constant Linearity OP AMP COMPARATOR VOS IBIAS Input Common-Mode Voltage Voltage Gain Output Sink Current Output Source Current Saturation Voltage VC e 1 0 VIN e 6 0V VIN e 6 0V Parameter

TA e 25 C see test circuit Conditions Min Typ Max Units

VIN e 250 mVp-p VIN e 250 mVp-p VIN e 250 mVp-p

1 kHz (Note2) 1 kHz (Note 2) 1 kHz (Note 2)

g 10

g 25

g 40

mV mV

30 35 5 10 15 1

mV mV mA V V

VIN e g 50 mVDC VIN e a 125 mVDC (Note 3) VIN e b125 mVDC (Note 3) V2 e V3 e 6 0V (Note 4) I2 e 0 V3 e 0 (Note 3) fIN e 1 kHz 5 kHz 10 kHz (Note 5) 09
b1 0

01 83 23 140 180

240 01

mA mA

10 03

a1 0


3 50 0 200 40 50 10 01

10 500 VCCb1 5V

mV nA V V mV mA mA...
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