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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

LM2907-N

LM2917-N

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

LM2907 and LM2917 Frequency to Voltage Converter

1 Features

1• 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

• Output Swings to Ground For Zero Frequency

Input

• Easy to Use; VOUT = fIN × VCC × R1 × C1

• Zener Regulator on Chip allows Accurate and

Stable Frequency to Voltage or Current

Conversion (LM2917)

2 Applications

• Over- and Under-Speed Sensing

• Frequency-to-Voltage Conversion (Tachometer)

• Speedometers

• Breaker Point Dwell Meters

• Hand-Held Tachometers

• Speed Governors

• Cruise Control

• Automotive Door Lock Control

• Clutch Control

• Horn Control

• Touch or Sound Switches

3 Description

The LM2907 and LM2917 devices are monolithic

frequency-to-voltage converters with a high gain op

amp 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 (8-pin

LM2907 and LM2917), and its output swings to

ground for a zero frequency input.

The op amp 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.

The two basic configurations offered include an 8-pin

device with a ground-referenced tachometer input

and an internal connection between the tachometer

output and the op amp noninverting input. This

version is well suited for single speed or frequency

switching or fully buffered frequency-to-voltage

conversion applications.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)

LM2907-N,

LM2917-N

PDIP (8) 6.35 mm × 9.81 mm

PDIP (14) 6.35 mm × 19.177 mm

SOIC (8) 3.91 mm × 4.90 mm

SOIC (14) 3.91 mm × 8.65 mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Minimum Component Tachometer Diagram

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Table of Contents

1 Features.................................................................. 1

2 Applications ........................................................... 1

3 Description............................................................. 1

4 Revision History..................................................... 2

5 Description (continued)......................................... 3

6 Pin Configuration and Functions......................... 3

7 Specifications......................................................... 5

7.1 Absolute Maximum Ratings ...................................... 5

7.2 ESD Ratings.............................................................. 5

7.3 Recommended Operating Conditions....................... 5

7.4 Thermal Information.................................................. 6

7.5 Electrical Characteristics........................................... 6

7.6 Typical Characteristics.............................................. 7

8 Parameter Measurement Information .................. 9

9 Detailed Description............................................ 10

9.1 Overview................................................................. 10

9.2 Functional Block Diagram....................................... 11

9.3 Feature Description................................................. 11

9.4 Device Functional Modes........................................ 12

10 Application and Implementation........................ 13

10.1 Application Information.......................................... 13

10.2 Typical Applications .............................................. 14

11 Power Supply Recommendations ..................... 27

12 Layout................................................................... 28

12.1 Layout Guidelines ................................................. 28

12.2 Layout Example .................................................... 28

13 Device and Documentation Support................. 29

13.1 Related Links ........................................................ 29

13.2 Receiving Notification of Documentation Updates 29

13.3 Community Resources.......................................... 29

13.4 Trademarks........................................................... 29

13.5 Electrostatic Discharge Caution............................ 29

13.6 Glossary................................................................ 29

14 Mechanical, Packaging, and Orderable

Information........................................................... 29

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision C (March 2013) to Revision D Page

• Added Device Information table, Pin Configuration and Functions section, ESD Ratings table, Recommended

Operating Conditions table, Thermal Information table, Parameter Measurement Information section, Detailed

Description section, Application and Implementation section, Power Supply Recommendations section, Layout

section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section...... 1

• Deleted Built-In Zener on LM2917 from Features.................................................................................................................. 1

• Deleted Only One RC Network Provides Frequency Doubling from Features....................................................................... 1

• Added Thermal Information table........................................................................................................................................... 6

• Changed tablenote text From: C2 = 0.22 mFd To: C2 = 0.22 µF.......................................................................................... 6

Changes from Revision B (March 2013) to Revision C Page

• Changed layout of National Semiconductor Data Sheet to TI format .................................................................................... 1

1TACH+ 8 TACH±/GND

2CP1 7 IN±

3CP2/IN+ 6 V+

4EMIT 5 COL

Not to scale

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5 Description (continued)

The more versatile configurations provide differential tachometer input and uncommitted op amp inputs. With this

version the tachometer input may be floated and the op amp becomes suitable for active filter conditioning of the

tachometer output.

Both of these configurations are available with an active shunt regulator connected across the power leads. The

regulator clamps the supply such that stable frequency-to-voltage and frequency-to-current operations are

possible with any supply voltage and a suitable resistor.

6 Pin Configuration and Functions

P and D Package

8-Pin PDIP and SOIC

Top View

Pin Functions: 8 Pins

PIN I/O DESCRIPTION

NAME NO.

COL 5 I The collector of the bipolar junction transistor

CP1 2 O A capacitor placed on this pin will be charged up to VCC/2 by a constant current source of 180 µA

typical at the start of every positive half cycle. At the beginning of negative half cycles this capacitor

is discharged the same amount at the same rate.

CP2/IN+ 3 I/O See pins CP1 and IN+. On 8-pin devices (8-pin LM2907 and LM2917) these two nodes share a pin

and are internally connected.

EMIT 4 O The emitter of the bipolar junction transistor

GND — G Ground

IN+ — I The noninverting input to the high gain op amp

IN– 7 I The inverting input to the high gain op amp

NC — — No connect

TACH+ 1 I Positive terminal for the input signal that leads to the noninverting terminal of the internal Schmitt-

Trigger comparator.

TACH–/GND 8 I Negative terminal for the input signal that leads to the noninverting terminal of the internal Schmitt-

Trigger comparator. (NOTE: On 8-pin devices, LM2907 and LM2917, this pin is internally connected

to ground and must be tied to ground externally to provide the reference voltage of the device).

V+ 6 I Supply voltage

1TACH+ 14 NC

2CP1 13 NC

3CP2 12 GND

4IN+ 11 TACH±

5EMIT 10 IN±

6NC 9 V+

7NC 8 COL

Not to scale

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NFF and D Package

14-Pin PDIP and SOIC

Top View

Pin Functions: 14 Pins

PIN I/O DESCRIPTION

NAME NO.

COL 8 I The collector of the bipolar junction transistor

CP1 2 O A capacitor placed on this pin will be charged up to VCC/2 by a constant current source of 180 µA

typical at the start of every positive half cycle. At the beginning of negative half cycles this capacitor is

discharged the same amount at the same rate.

CP2 3 O The charge pump sources current out of this pin equal to the absolute value of the capacitor current

on CP1. A resistor and capacitor in parallel connected to this pin filters the current pulses into the

output voltage.

EMIT 5 O The emitter of the bipolar junction transistor

GND 12 G Ground

IN+ 4 I The noninverting input to the high gain op amp

IN– 10 I The inverting input to the high gain op amp

NC 6, 7, 13, 14 — No connect

TACH+ 1 I Positive terminal for the input signal that leads to the noninverting terminal of the internal Schmitt-

Trigger comparator.

TACH– 11 I Negative terminal for the input signal that leads to the noninverting terminal of the internal Schmitt-

Trigger comparator.

V+ 9 I Supply voltage

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(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings

only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended

Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and

specifications.

7 Specifications

7.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)(2)

MIN MAX UNIT

Supply voltage 28 V

Supply current (Zener options) 25 mA

Collector voltage 28 V

Differential input voltage Tachometer, op amp, and comparator 28 V

Input voltage Tachometer LM2907 (8), LM2917 (8) –28 28 VLM2907 (14), LM2917 (14) 0 28

Op amp and comparator 0 28

Power dissipation LM29x7 (8) 1200 mW

LM29x7 (14) 1580

Soldering information PDIP package Soldering (10 s) 260 °C

SOIC package Vapor phase (60 s) 215

Infrared (15 s) 220

Operating temperature, TJ–40 85 °C

Storage temperature, Tstg –65 150 °C

(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

7.2 ESD Ratings VALUE UNIT

V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JESD22-A114(1) ±1000 V

Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±250

7.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted) MIN NOM MAX UNIT

Input voltage LM2907 (8), LM2917 (8) –28 28 V

LM2907 (14), LM2917 (14) 0 28 V

Output sink current 50 mA

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(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application

report.

7.4 Thermal Information

THERMAL METRIC(1) LM2907, LM2917

UNITP (PDIP) D (SOIC) NFF (PDIP) D (SOIC)

8 PINS 8 PINS 14 PINS 14 PINS

RθJA Junction-to-ambient thermal resistance 77.6 110 69.1 83.7 °C/W

RθJC(top) Junction-to-case (top) thermal resistance 80.5 53.9 64.8 42.1 °C/W

RθJB Junction-to-board thermal resistance 54.8 50.4 49.1 38 °C/W

ψJT Junction-to-top characterization parameter 37.6 9.1 35.1 7.7 °C/W

ψJB Junction-to-board characterization

parameter 54.8 49.9 49 37.7 °C/W

RθJC(bot) Junction-to-case (bottom) thermal

resistance — — — — °C/W

(1) Hysteresis is the sum VTH – (–VTH), offset voltage is their difference. See test circuit.

(2) VOH = 0.75 × VCC – 1 VBE and VOL = 0.25 × VCC – 1 VBE, therefore VOH – VOL = VCC / 2. The difference (VOH – VOL) and the mirror gain

(I2/ I3) are the two factors that cause the tachometer gain constant to vary from 1.

(3) Ensure that when choosing the time constant R1 × C1 that the maximum anticipated output voltage at CP2/IN+ can be reached with I3×

R1. The maximum value for R1 is limited by the output resistance of CP2/IN+ which is greater than 10 MΩtypically.

(4) Nonlinearity is defined as the deviation of VOUT (at CP2/IN+) for fIN = 5 kHz from a straight line defined by the VOUT at 1 kHz and VOUT

at 10 kHz. C1 = 1000 pF, R1 = 68 kΩand C2 = 0.22 µF.

7.5 Electrical Characteristics

VCC = 12 VDC, TA= 25°C, see test circuit

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

TACHOMETER

Input thresholds VIN = 250 mVp-p at 1 kHz(1) ±10 ±25 ±40 mV

Hysteresis VIN = 250 mVp-p at 1 kHz(1) 30 mV

LM29x7 offset voltage VIN = 250 mVp-p at 1 kHz(1) 3.5 10 mV

VIN = 250 mVp-p at 1 kHz (8-pin LM29x7)(1) 5 15

Input bias current VIN = ±50 mVDC 0.1 1 μA

VOH High level output voltage For CP1, VIN = 125 mVDC(2) 8.3 V

VOL Low level output voltage For CP1, VIN = –125 mVDC(2) 2.3 V

I2, I3Output current V2 = V3 = 6 V(3) 140 180 240 μA

I3Leakage current I2 = 0, V3 = 0 0.1 μA

K Gain constant See(2) 0.9 1 1.1

Linearity fIN = 1 kHz, 5 kHz, or 10 kHz(4) –1% 0.3% 1%

OP AMP AND COMPARATOR

VOS Input offset voltage VIN = 6 V 3 10 mV

IBIAS Bias current VIN = 6 V 50 500 nA

Input common-mode voltage 0 VCC–1.5 V

Voltage gain 200 V/mV

Output sink current VC= 1 40 50 mA

Output source current VE= VCC –2 10 mA

Saturation voltage

ISINK = 5 mA 0.1 0.5 V

ISINK = 20 mA 1 V

ISINK = 50 mA 1 1.5 V

ZENER REGULATOR

Regulator voltage RDROP = 470 Ω7.56 V

Series resistance 10.5 15 Ω

Temperature stability 1 mV/°C

Total supply current 3.8 6 mA

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7.6 Typical Characteristics

Figure 1. Tachometer Linearity vs Temperature Figure 2. Tachometer Linearity vs Temperature

Figure 3. Total Supply Current Figure 4. Zener Voltage vs Temperature

Figure 5. Normalized Tachometer Output (K)

vs Temperature Figure 6. Normalized Tachometer Output (K)

vs Temperature

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Typical Characteristics (continued)

Figure 7. Tachometer Currents I2and I3vs Supply Voltage Figure 8. Tachometer Currents I2and I3vs Temperature

Figure 9. Tachometer Linearity vs R1 Figure 10. Tachometer Input Hysteresis vs Temperature

Figure 11. Op Amp Output Transistor Characteristics Figure 12. Op Amp Output Transistor Characteristics

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8 Parameter Measurement Information

Figure 13. Test Circuit

Figure 14. Tachometer Input Threshold Measurement

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9 Detailed Description

9.1 Overview

The LM29x7 frequency-to-voltage converter features two separate inputs to monitor the signal. In the 8-pin

devices, one of these inputs is internally grounded and therefore it monitors the remaining input for zero

crossings. In the 14-pin devices, both of these inputs are open and it instead detects whenever the differential

voltage switches polarity. Therefore, the input comparator outputs a square wave of equal frequency to the input.

A charge pump system is used to translate the frequency of this square wave to a voltage. At the start of every

positive half cycle of the input signal a 180-µA constant current charges C1 until its voltage has increased by

VCC/2. The capacitor is held at that voltage until the input signal begins a negative half cycle. Then the 180-µA

constant current discharges capacitor C1 until its voltage has dropped by VCC/2. This voltage is held until the

next positive half cycle and the process repeats. This generates pulses of current flowing into and out of

capacitor C1 at the same frequency as the input signal. For every full cycle, the charge pump mirrors both

current pulses as positive current pulses into the parallel combination of resistor R1 and capacitor C2. Therefore

every full cycle, the amount of charge leaving pin 3 is equal to the sum of the charge entering C1 and leaving C1.

Because the voltage at pin 3 is equal to I3(avg) × R1, I(avg) is calculated in Equation 1.

I3(avg) = Q/t = (Qcharge + Qdischarge) / (1 / f) = 2 × Q × f = 2 × C1 × (VCC/2) × f = C1 × VCC × f (1)

This average current will be flowing across R1, giving the output voltage in Equation 2.

Vo = R1 × C1 × VCC × f (2)

C2 acts as a filter to smooth the pulses of current and does not affect the output voltage. However, the size of C2

determines both the output response time for changes in frequency and the amount of output voltage ripple.

The voltage generated is then fed in a high gain op amp. This op amp drives a bipolar transistor whose collector

and emitter are each broken out to a pin. The LM29x7 has the flexibility to be configured a variety of ways to

meet system requirements including voltage output, driving loads, operating a relay, and more.

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9.2 Functional Block Diagram

*This connection made on 8-pin LM2907 and LM2917 only.

**This connection made on LM2917 and 8-pin LM2917 only.

9.3 Feature Description

9.3.1 Differential Input

This device features a Schmitt-Trigger comparator that is the first stage in converting the input signal. Every time

the output of the comparator flips between high and low correlates to a half cycle elapsing on the input signal. On

the LM29x7-8 devices, one terminal of this comparator is internally connected to ground. This requires that the

input signal cross zero volts in order for device to detect the frequency. On the LM29x7 devices, the input

terminals to the Schmitt-Trigger comparator are both available for use. This open terminal allows the potential at

which the comparator’s output is flipped to be applied externally. This allows the device to accept signals with DC

offset or compare differential inputs.

9.3.2 Configurable

While the ratio of output voltage to input frequency is dependent on supply voltage, it is easily adjusted through

the combination of one resistor and one capacitor, R1 and C1. The formula for calculating the expected output

voltage is in Equation 3.

VOUT = VCC × f × C1 × R1. (3)

The sizes of R1 and C1 have other effects on the system such as maximum frequency and output linearity. See

Choosing R1 and C1 for detailed instructions on sizing components.

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Feature Description (continued)

9.3.3 Output Stage

The output voltage generated by the charge pump is fed in the noninverting terminal of a high gain op amp. This

op amp then drives and uncommitted bipolar junction transistor. This allows the LM2907 to be configured a

variety of ways to meet system needs. The output voltage can be buffered and used to drive a load (see

Figure 15) or an output threshold can be given to trigger a load switch (see Figure 18).

9.4 Device Functional Modes

9.4.1 Grounded Input Devices (8-Pin LM2907 and LM2917)

These devices have one of the two Schmitt-Trigger comparator inputs internally grounded and must be externally

connected to the system ground as well. This configuration monitors the remaining terminal for zero crossings.

9.4.2 Differential Input Devices (LM2907 and LM2917)

These devices have both inputs to the Schmitt-Trigger comparator available and broken out to pins 1 and 11.

This configuration allows a new switching threshold provided in the case of signals with DC offset or to intake a

differential pair and switch based on voltage difference.

c(AVG) IN CC IN

Q= i =C1× ×(2f ) = V ×f ×C1

T 2

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10 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

10.1 Application Information

The LM2907 series of tachometer circuits is designed for minimum external part count applications and

maximum versatility. To fully exploit its features and advantages, first examine its theory of operation. The first

stage of operation is a differential amplifier driving a positive feedback flip-flop circuit. The input threshold voltage

is the amount of differential input voltage at which the output of this stage changes state. Two options (8-pin

LM2907 and LM2917) have one input internally grounded so that an input signal must swing above and below

ground and exceed the input thresholds to produce an output. This is offered specifically for magnetic variable

reluctance pickups which typically provide a single-ended AC output. This single input is also fully protected

against voltage swings to ±28 V, which are easily attained with these types of pickups.

The differential input options (LM2907, LM2917) give the user the option of setting his own input switching level

and still have the hysteresis around that level for excellent noise rejection in any application. Of course to allow

the inputs to attain common-mode voltages above ground, input protection is removed and neither input should

be taken outside the limits of the supply voltage being used. It is very important that an input not go below

ground without some resistance in its lead to limit the current that will then flow in the epi-substrate diode.

Following the input stage is the charge pump where the input frequency is converted to a DC voltage. To do this

requires one timing capacitor, one output resistor, and an integrating or filter capacitor. When the input stage

changes state (due to a suitable zero crossing or differential voltage on the input) the timing capacitor is either

charged or discharged linearly between two voltages whose difference is VCC/2. Then in one half cycle of the

input frequency or a time equal to 1/2 fIN the change in charge on the timing capacitor is equal to VCC/2 × C1.

The average amount of current pumped into or out of the capacitor is shown in Equation 4.

(4)

The output circuit mirrors this current very accurately into the load resistor R1, connected to ground, such that if

the pulses of current are integrated with a filter capacitor, then VO= ic× R1, and the total conversion formula

becomes Equation 5.

VO= VCC × fIN × C1 × R1 × K

where

• K is the gain constant (typically 1) (5)

The size of C2 is dependent only on the amount of ripple voltage allowable and the required response time.

CC CC IN

RIPPLE 2

V V ×f ×C1

V = × × 1 pk-pk

2 C2 I

§ ·



¨ ¸

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10.2 Typical Applications

10.2.1 Minimum Component Tachometer

Figure 15. Minimum Component Tachometer Diagram

10.2.1.1 Design Requirements

• C1: This capacitor is charged and discharged every cycle by a 180-µA typical current source. Smaller

capacitors can be charged quicker therefore increasing the maximum readable frequency. However, lower

capacitors values reduce the output voltage produced for a given frequency. C1 must not be sized lower than

500-pF die to its role in internal compensation.

• R1: This resistor produces the output voltage from current pulses source by the internal charge pump. Higher

values increase the output voltage for a given frequency, but too large will degrade the output’s linearity.

Because the current pulses are a fixed magnitude of 180 µA typical, R1 must be big enough to produce the

maximum desired output voltage at maximum input frequency. At maximum input frequency the pulse train

duty cycle is 100%, therefore the average current is 180 µA and R1 = Vo(max) / 180 µA.

• C2: This capacitor filters the ripple produced by the current pulses sourced by the charge pump. Large values

reduce the output voltage ripple but increase the output’s response time to changes in input frequency.

• Rload: The load resistance must be large enough that at maximum output voltage, the current is under the

rated value of 50 mA.

10.2.1.2 Detailed Design Procedure

10.2.1.2.1 Choosing R1 and C1

There are some limitations on the choice of R1 and C1 which should be considered for optimum performance.

The timing capacitor also provides internal compensation for the charge pump and must be kept larger than 500

pF for very accurate operation. Smaller values can cause an error current on R1, especially at low temperatures.

Several considerations must be met when choosing R1. The output current at pin 3 is internally fixed and

therefore VO/R1 must be less than or equal to this value. If R1 is too large, it can become a significant fraction of

the output impedance at pin 3 which degrades linearity. Also output ripple voltage must be considered and the

size of C2 is affected by R1. An expression that describes the ripple content on pin 3 for a single R1C2

combination is in Equation 6.

(6)

R1 can be chosen independent of ripple. However, response time, or the time it takes VOUT to stabilize at a new

voltage, increases as the size of C2 increases, so a compromise between ripple, response time, and linearity

must be chosen carefully.

As a final consideration, the maximum attainable input frequency is determined by VCC, C1, and I2in Equation 7.

MAX CC

f = C1×V

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Typical Applications (continued)

(7)

10.2.1.2.2 Using Zener Regulated Options (LM2917)

For those applications where an output voltage or current must be obtained independent of supply voltage

variations, the LM2917 is offered. The most important consideration in choosing a dropping resistor from the

unregulated supply to the device is that the tachometer and op amp circuitry alone require about 3 mA at the

voltage level provided by the Zener. At low supply voltages there must be some current flowing in the resistor

above the 3-mA circuit current to operate the regulator. As an example, if the raw supply varies from 9 V to 16 V,

a resistance of 470 Ωminimizes the Zener voltage variation to 160 mV. If the resistance goes under 400 Ωor

over 600 Ω, the Zener variation quickly rises above 200 mV for the same input variation.

10.2.1.3 Application Curves

C1 = .01 µF C2 = 1 µF R1 = 100 kΩ

Rdrop = 910 ΩZener Regulated VCC = 7.58 V

Figure 16. Output Response to an Increase

in Input Frequency

C1 = .01 µF C2 = 1 µF R1 = 100 kΩ

Rdrop = 910 ΩZener Regulated VCC = 7.58 V

Figure 17. Output Voltage Ripple

10.2.2 Other Application Circuits

This section shows application circuit examples using the LM2907-N and LM2917-N devices. Customers must

fully validate and test these circuits before implementing a design based on these examples.

SPACER

Load is energized when fIN ≥(1 / ( 2 × RC))

Figure 18. Speed Switch

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Typical Applications (continued)

Figure 19. Zener Regulated Frequency to Voltage Converter

SPACER

Figure 20. Breaker Point Dwell Meter

SPACER

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Typical Applications (continued)

VO= 6 V at 400 Hz or 6000 ERPM (8 Cylinder Engine)

Figure 21. Voltage Driven Meter Indicating Engine RPM

SPACER

IO= 10 mA at 300 Hz or 6000 ERPM (6 Cylinder Engine)

Figure 22. Current Driven Meter Indicating Engine RPM

SPACER

LM2907-N

LM2917-N

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LM2907-N LM2917-N

Typical Applications (continued)

VOUT = 1 V to 10 V for CX = 0.01 to 0.1 mFd and R = 111 kΩ

Figure 23. Capacitance Meter

SPACER

Figure 24. Two-Wire Remote Speed Switch

SPACER

LM2907-N

LM2917-N

www.ti.com

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

Product Folder Links: LM2907-N LM2917-N

Typical Applications (continued)

V3 steps up in voltage by the amount of (VCC × C1) / C2, for each complete input cycle (2 zero crossings).

For example: if C2 = 200 × C1 after 100 consecutive input cycles, then V3 = 1/2 × VCC.

Figure 25. 100 Cycle Delay Switch

SPACER

Flashing begins when fIN ≥100 Hz

Flash rate increases with input frequency increase beyond trip point.

Figure 26. Flashing LED Indicates Over-Speed

SPACER

LM2907-N

LM2917-N

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LM2907-N LM2917-N

fPOLE = 0.707 / (2 × π× RC)

τRESPONSE = 2.57 / (2 × π× fPOLE)

Figure 27. Frequency to Voltage Converter With 2 Pole Butterworth Filter to Reduce Ripple

10.2.2.1 Variable Reluctance Magnetic Pickup Buffer Circuits

Precision two-shot output frequency is twice the input frequency

Pulse width = (VCC / 2) × (C1 / 12)

Pulse height = VZENER

Figure 28. Magnetic Pickup Buffer With Zener Regulated Output Magnitude

SPACER

LM2907-N

LM2917-N

www.ti.com

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

Product Folder Links: LM2907-N LM2917-N

Figure 29. Magnetic Pickup Buffer With 1/2 VCC Output Magnitude

10.2.2.2 Finger Touch or Contact Switch

Figure 30. Finger Touch or Contact Switch Diagram

SPACER

Figure 31. System Output in Response to Consecutive Button Presses

LM2907-N

LM2917-N

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LM2907-N LM2917-N

10.2.2.3 Over-Speed Latch

Output latches when fIN = (R2 / (R1 + R2)) × (1 / RC).

Output is reset by removing VCC.

Figure 32. Over-Speed Latch Circuit Diagram

SPACER

Figure 33. VOUT vs FIN

LM2907-N

LM2917-N

www.ti.com

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

Product Folder Links: LM2907-N LM2917-N

10.2.2.4 Frequency Switch Applications

Some frequency switch applications may require hysteresis in the comparator function which can be

implemented in several ways. Example circuits are shown in Figure 34 to Figure 36.

Figure 34. Frequency Switch With Resistor Divider Threshold

SPACER

Figure 35. Frequency Switch With Added Hysteresis

SPACER

LM2907-N

LM2917-N

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LM2907-N LM2917-N

Figure 36. Frequency Switch With Added Hysteresis

10.2.2.4.1 Application Curves

Figure 37. VOUT vs V3 Figure 38. VOUT vs V3

10.2.2.5 Anti-Skid Circuits

10.2.2.5.1 Select-Low Circuit

Figure 39. Select-Low Circuit Diagram

LM2907-N

LM2917-N

www.ti.com

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

Product Folder Links: LM2907-N LM2917-N

SPACER

VOUT is proportional to the lower of the two input wheel speeds

Figure 40. VOUT vs Wheel Speed

10.2.2.5.2 Select-High Circuit

Figure 41. Select-High Circuit Diagram

SPACER

VOUT is proportional to the higher of the two input wheel speeds

Figure 42. VOUT vs Wheel Speed

LM2907-N

LM2917-N

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LM2907-N LM2917-N

10.2.2.5.3 Select-Average Circuit

Figure 43. Select-Average Circuit Diagram

10.2.2.6 Changing the Output Voltage for an Input Frequency of Zero

Figure 44. Tachometer With Adjustable Zero Speed Voltage Output

SPACER

Figure 45. VOUT vs Frequency Plot Shifted to Produce 1 V at Zero Speed

LM2907-N

LM2917-N

www.ti.com

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

Product Folder Links: LM2907-N LM2917-N

10.2.2.7 Changing Tachometer Gain Curve or Clamping the Minimum Output Voltage

Figure 46. Tachometer With Output Clamped at Low Speeds

SPACER

Figure 47. VOUT vs Frequency Plot With Output Clamped at Low Speeds

11 Power Supply Recommendations

This family of devices is designed to operate from a supply voltage up to 28 V. For the 8-pin LM2907 and

LM2917, devices with a fixed ground reference for TACH–, the tachometer inputs can intake voltages between

±28 V. LM2907 and LM2917 devices have both tachometer inputs available at the cost of input protection

features. This means neither input should be taken outside of the supply voltage range without additional

precautions (see Application Information).

LM2907-N

LM2917-N

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LM2907-N LM2917-N

12 Layout

12.1 Layout Guidelines

• Bypass capacitors must be placed as close as possible to the supply pin. When using a through-hole

package, it is acceptable to place the bypass capacitor on the bottom layer. All other components must be

placed as close to the device as possible.

• Use of a ground plane is recommended to provide a low-impedance ground across the circuit.

• Feedback loops must use short and wide traces.

12.2 Layout Example

Figure 48. Layout Recommendation

LM2907-N

LM2917-N

www.ti.com

SNAS555D –JUNE 2000–REVISED DECEMBER 2016

Product Folder Links: LM2907-N LM2917-N

13 Device and Documentation Support

13.1 Related Links

The table below lists quick access links. Categories include technical documents, support and community

resources, tools and software, and quick access to sample or buy.

Table 1. Related Links

PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL

DOCUMENTS TOOLS &

SOFTWARE SUPPORT &

COMMUNITY

LM2907-N Click here Click here Click here Click here Click here

LM2917-N Click here Click here Click here Click here Click here

13.2 Receiving Notification of Documentation Updates

To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper

right corner, click on Alert me to register and receive a weekly digest of any product information that has

changed. For change details, review the revision history included in any revised document.

13.3 Community Resources

The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective

contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of

Use.

TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration

among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help

solve problems with fellow engineers.

Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and

contact information for technical support.

13.4 Trademarks

E2E is a trademark of Texas Instruments.

All other trademarks are the property of their respective owners.

13.5 Electrostatic Discharge Caution

This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with

appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.

ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more

susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.

13.6 Glossary

SLYZ022 —TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.

14 Mechanical, Packaging, and Orderable Information

The following pages include mechanical, packaging, and orderable information. This information is the most

current data available for the designated devices. This data is subject to change without notice and revision of

this document. For browser-based versions of this data sheet, refer to the left-hand navigation.

PACKAGE OPTION ADDENDUM

www.ti.com 11-Jan-2021

Addendum-Page 1

PACKAGING INFORMATION

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead finish/

Ball material

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LM2907M NRND SOIC D 14 55 Non-RoHS

& Green Call TI Call TI -40 to 85 LM2907M

LM2907M-8 NRND SOIC D 8 95 Non-RoHS

& Green Call TI Call TI -40 to 85 LM29

07M-8

LM2907M-8/NOPB ACTIVE SOIC D 8 95 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM29

07M-8

LM2907M/NOPB ACTIVE SOIC D 14 55 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM2907M

LM2907MX NRND SOIC D 14 2500 Non-RoHS

& Green Call TI Call TI -40 to 85 LM2907M

LM2907MX-8/NOPB ACTIVE SOIC D 8 2500 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM29

07M-8

LM2907MX/NOPB ACTIVE SOIC D 14 2500 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM2907M

LM2907N-8/NOPB ACTIVE PDIP P 8 40 RoHS & Green Call TI | SN Level-1-NA-UNLIM -40 to 85 LM

2907N-8

LM2907N/NOPB ACTIVE PDIP NFF 14 25 RoHS & Green Call TI | SN Level-1-NA-UNLIM -40 to 85 LM2907N

LM2917M-8 NRND SOIC D 8 95 Non-RoHS

& Green Call TI Call TI -40 to 85 LM29

17M-8

LM2917M-8/NOPB ACTIVE SOIC D 8 95 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM29

17M-8

LM2917M/NOPB ACTIVE SOIC D 14 55 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM2917M

LM2917MX-8/NOPB ACTIVE SOIC D 8 2500 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM29

17M-8

LM2917MX/NOPB ACTIVE SOIC D 14 2500 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM2917M

LM2917N-8/NOPB ACTIVE PDIP P 8 40 RoHS & Green Call TI | SN Level-1-NA-UNLIM -40 to 85 LM

2917N-8

LM2917N/NOPB ACTIVE PDIP NFF 14 25 RoHS & Green Call TI | SN Level-1-NA-UNLIM -40 to 85 LM2917N

(1) The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

PACKAGE OPTION ADDENDUM

www.ti.com 11-Jan-2021

Addendum-Page 2

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance

do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may

reference these types of products as "Pb-Free".

RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.

Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based

flame retardants must also meet the <=1000ppm threshold requirement.

(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation

of the previous line and the two combined represent the entire Device Marking for that device.

(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two

lines if the finish value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information

provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and

continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.

TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device Package

Type Package

Drawing Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

(mm) B0

(mm) K0

(mm) P1

(mm) W

(mm) Pin1

Quadrant

LM2907MX SOIC D 14 2500 330.0 16.4 6.5 9.35 2.3 8.0 16.0 Q1

LM2907MX-8/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1

LM2907MX/NOPB SOIC D 14 2500 330.0 16.4 6.5 9.35 2.3 8.0 16.0 Q1

LM2917MX-8/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1

LM2917MX/NOPB SOIC D 14 2500 330.0 16.4 6.5 9.35 2.3 8.0 16.0 Q1

PACKAGE MATERIALS INFORMATION

www.ti.com 29-Sep-2019

Pack Materials-Page 1

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

LM2907MX SOIC D 14 2500 367.0 367.0 35.0

LM2907MX-8/NOPB SOIC D 8 2500 367.0 367.0 35.0

LM2907MX/NOPB SOIC D 14 2500 367.0 367.0 35.0

LM2917MX-8/NOPB SOIC D 8 2500 367.0 367.0 35.0

LM2917MX/NOPB SOIC D 14 2500 367.0 367.0 35.0

PACKAGE MATERIALS INFORMATION

www.ti.com 29-Sep-2019

Pack Materials-Page 2

MECHANICAL DATA

N0014A

www.ti.com

N14A (Rev G)

NFF0014A

www.ti.com

PACKAGE OUTLINE

.228-.244 TYP

[5.80-6.19]

.069 MAX

[1.75]

6X .050

[1.27]

8X .012-.020

[0.31-0.51]

.150

[3.81]

.005-.010 TYP

[0.13-0.25]

0 - 8 .004-.010

[0.11-0.25]

.010

[0.25]

.016-.050

[0.41-1.27]

4X (0 -15 )

.189-.197

[4.81-5.00]

NOTE 3

B .150-.157

[3.81-3.98]

NOTE 4

4X (0 -15 )

(.041)

[1.04]

SOIC - 1.75 mm max heightD0008A

SMALL OUTLINE INTEGRATED CIRCUIT

4214825/C 02/2019

NOTES:

1. Linear dimensions are in inches [millimeters]. Dimensions in parenthesis are for reference only. Controlling dimensions are in inches.

Dimensioning and tolerancing per ASME Y14.5M.

2. This drawing is subject to change without notice.

3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not

exceed .006 [0.15] per side.

4. This dimension does not include interlead flash.

5. Reference JEDEC registration MS-012, variation AA.

.010 [0.25] C A B

PIN 1 ID AREA

SEATING PLANE

.004 [0.1] C

SEE DETAIL A

DETAIL A

TYPICAL

SCALE 2.800

www.ti.com

EXAMPLE BOARD LAYOUT

.0028 MAX

[0.07]

ALL AROUND

.0028 MIN

[0.07]

ALL AROUND

(.213)

[5.4]

6X (.050 )

[1.27]

8X (.061 )

[1.55]

8X (.024)

[0.6]

(R.002 ) TYP

[0.05]

SOIC - 1.75 mm max heightD0008A

SMALL OUTLINE INTEGRATED CIRCUIT

4214825/C 02/2019

NOTES: (continued)

6. Publication IPC-7351 may have alternate designs.

7. Solder mask tolerances between and around signal pads can vary based on board fabrication site.

METAL SOLDER MASK

OPENING

NON SOLDER MASK

DEFINED

SOLDER MASK DETAILS

EXPOSED

METAL

OPENING

SOLDER MASK METAL UNDER

SOLDER MASK

DEFINED

EXPOSED

METAL

LAND PATTERN EXAMPLE

EXPOSED METAL SHOWN

SCALE:8X

SYMM

SEE

DETAILS

SYMM

www.ti.com

EXAMPLE STENCIL DESIGN

8X (.061 )

[1.55]

8X (.024)

[0.6]

6X (.050 )

[1.27] (.213)

[5.4]

(R.002 ) TYP

[0.05]

SOIC - 1.75 mm max heightD0008A

SMALL OUTLINE INTEGRATED CIRCUIT

4214825/C 02/2019

NOTES: (continued)

8. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate

design recommendations.

9. Board assembly site may have different recommendations for stencil design.

SOLDER PASTE EXAMPLE

BASED ON .005 INCH [0.125 MM] THICK STENCIL

SCALE:8X

SYMM

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