LM2917EP

LM2907EP/LM2917EP Enhanced Plastic Frequency to Voltage Converter June 2004 LM2907EP/LM2917EP Enhanced Plastic Frequency to Voltage Converter General Description The LM2907EP, LP2917EP 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 (LM2907-8EP, LM2917-8EP) 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. 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 non-inverting input. This version is well suited for single speed or frequency switching or fully buffered frequency to voltage conversion applications. 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. ENHANCED PLASTIC • Extended Temperature Performance of −40˚C to +85˚C • Baseline Control - Single Fab & Assembly Site Features n Ground referenced tachometer input interfaces directly with variable reluctance magnetic pickups n Op amp/comparator has floating transistor output n 50 mA sink or source to operate relays, solenoids, meters, or LEDs n Frequency doubling for low ripple n Tachometer has built-in hysteresis with either differential input or ground referenced input n Built-in zener on LM2917EP n ± 0.3% linearity typical n Ground referenced tachometer is fully protected from damage due to swings above VCC and below ground Advantages n n n n 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 (LM2917EP) Applications n Selected Military Applications n Selected Avionics Applications • • • • Process Change Notification (PCN) Qualification & Reliability Data Solder (PbSn) Lead Finish is standard Enhanced Diminishing Manufacturing Sources (DMS) Support Ordering Information PART NUMBER LM2907MX-8EP LM2917MXEP (Notes 1, 2) VIN PART NUMBER V62/04635-01 V62/04635-02 TBD NS PACKAGE NUMBER (Note 3) M08A M14A TBD Note 1: For the following (Enhanced Plastic) versions, check for availablility: LM2907M-8EP, LM2907MEP, LM2907MXEP, LM2907N-8EP, LM2907NEP and LM2917M-8EP, LM2917MX-8EP, LM2917MEP, LM2917N-8EP, LM2917NEP. Parts listed with an "X" are provided in Tape & Reel and parts without an "X" are in Rails. Note 2: FOR ADDITIONAL ORDERING AND PRODUCT INFORMATION, PLEASE VISIT THE ENHANCED PLASTIC WEB SITE AT: www.national.com/ mil Note 3: Refer to package details under Physical Dimensions © 2004 National Semiconductor Corporation DS200906 www.national.com LM2907EP/LM2917EP Enhanced Plastic Block and Connection Diagrams Dual-In-Line and Small Outline Packages, Top Views 20090601 LM2907-8 See NS Package Number M08A or N08E 20090602 LM2917-8 See NS Package Number M08A or N08E 20090603 20090604 LM2907 See NS Package Number M14A or N14A LM2917 See NS Package Number M14A or N14A www.national.com 2 LM2907EP/LM2917EP Enhanced Plastic Absolute Maximum Ratings (Note 4) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage Collector Voltage Differential Input Voltage Tachometer Op Amp/Comparator Input Voltage Range Tachometer LM2907-8EP, LM2917-8EP LM2907EP, LM2917EP 28V 28V 28V 28V Op Amp/Comparator Power Dissipation (Note 4) LM2907-8EP, LM2917-8EP LM2907-14EP, LM2917-14EP Operating Temperature Range Storage Temperature Range Soldering Information Dual-In-Line Package Soldering (10 seconds) Small Outline Package Vapor Phase (60 seconds) 0.0V to +28V 1200 mW 1580 mW −40˚C to +85˚C −65˚C to +150˚C 260˚C 215˚C 220˚C ± 28V 0.0V to +28V Infrared (15 seconds) Electrical Characteristics Symbol TACHOMETER Input Thresholds Hysteresis Offset Voltage LM2907EP/LM2917EP LM2907-8EP/LM2917-8EP Input Bias Current VOH VOL I 2, 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 Parameter VCC = 12 VDC, TA = 25˚C, see test circuit Conditions VIN = 250 mVp-p @ 1 kHz (Note 5) VIN = 250 mVp-p @ 1 kHz (Note 5) VIN = 250 mVp-p @ 1 kHz (Note 5) 3.5 5 VIN = ± 50 mVDC VIN = +125 mVDC (Note 6) VIN = −125 mVDC (Note 6) V2 = V3 = 6.0V (Note 7) I2 = 0, V3 = 0 (Note 6) fIN = 1 kHz, 5 kHz, 10 kHz (Note 8) VIN = 6.0V VIN = 6.0V 0 200 VC = 1.0 VE = VCC −2.0 ISINK = 5 mA ISINK = 20 mA ISINK = 50 mA 1.0 7.56 10.5 +1 3.8 6 15 40 50 10 0.1 0.5 1.0 1.5 0.9 −1.0 1.0 0.3 3 50 140 0.1 8.3 2.3 180 240 0.1 1.1 +1.0 10 500 VCC−1.5V % mV nA V V/mV mA mA V V V V Ω mV/˚C mA 10 15 1 mV mV µA V V µA µA Min Typ Max Units mV mV ± 10 ± 25 30 ± 40 ZENER REGULATOR Regulator Voltage Series Resistance Temperature Stability Total Supply Current RDROP = 470Ω Note 4: For operation in ambient temperatures above 25˚C, the device must be derated based on a 150˚C maximum junction temperature and a thermal resistance of 101˚C/W junction to ambient for LM2907-8EP and LM2917-8EP, and 79˚C/W junction to ambient for LM2907-14EP and LM2917-14EP. Note 5: Hysteresis is the sum +VTH − (−VTH), offset voltage is their difference. See test circuit. Note 6: VOH is equal to 3⁄4 x VCC − 1 VBE, VOL is equal to 1⁄4 x 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 1.0. Note 7: Be sure when choosing the time constant R1 x C1 that R1 is such that the maximum anticipated output voltage at pin 3 can be reached with I3 x R1. The maximum value for R1 is limited by the output resistance of pin 3 which is greater than 10 MΩ typically. Note 8: Nonlinearity is defined as the deviation of VOUT (@ pin 3) for fIN = 5 kHz from a straight line defined by the VOUT @ 1 kHz and VOUT @ 10 kHz. C1 = 1000 pF, R1 = 68k and C2 = 0.22 mFd. 3 www.national.com LM2907EP/LM2917EP Enhanced Plastic Test Circuit and Waveform 20090606 Tachometer Input Threshold Measurement 20090607 www.national.com 4 LM2907EP/LM2917EP Enhanced Plastic Typical Performance Characteristics Total Supply Current Zener Voltage vs Temperature 20090640 20090641 Normalized Tachometer Output vs Temperature Normalized Tachometer Output vs Temperature 20090642 20090643 Tachometer Currents I2 and I3 vs Supply Voltage Tachometer Currents I2 and I3 vs Temperature 20090644 20090645 5 www.national.com LM2907EP/LM2917EP Enhanced Plastic Typical Performance Characteristics Tachometer Linearity vs Temperature (Continued) Tachometer Linearity vs Temperature 20090646 20090647 Tachometer Linearity vs R1 Tachometer Input Hysteresis vs Temperature 20090648 20090649 Op Amp Output Transistor Characteristics Op Amp Output Transistor Characteristics 20090651 20090650 www.national.com 6 LM2907EP/LM2917EP Enhanced Plastic Applications Information The LM2907EP series of tachometer circuits is designed for minimum external part count applications and maximum versatility. In order to fully exploit its features and advantages let’s 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 (LM2907-8EP, LM2917-8EP) 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 ± 28V, which are easily attained with these types of pickups. The differential input options (LM2907EP, LM2917EP) 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 in order 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 x C1. The average amount of current pumped into or out of the capacitor then is: 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 should 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: It appears 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 I2: 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 x R1, and the total conversion equation becomes: VO = VCC x fIN x C1 x R1 x K Where K is the gain constant — typically 1.0. The size of C2 is dependent only on the amount of ripple voltage allowable and the required response time. USING ZENER REGULATED OPTIONS (LM2917EP) For those applications where an output voltage or current must be obtained independent of supply voltage variations, the LM2917EP 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 9V to 16V, a resistance of 470Ω will minimize the zener voltage variation to 160 mV. If the resistance goes under 400Ω or over 600Ω the zener variation quickly rises above 200 mV for the same input variation. 7 www.national.com LM2907EP/LM2917EP Enhanced Plastic Typical Applications Minimum Component Tachometer 20090608 20090609 www.national.com 8 LM2907EP/LM2917EP Enhanced Plastic Typical Applications (Continued) Zener Regulated Frequency to Voltage Converter 20090610 Breaker Point Dwell Meter 20090611 9 www.national.com LM2907EP/LM2917EP Enhanced Plastic Typical Applications (Continued) Voltage Driven Meter Indicating Engine RPM VO = 6V @ 400 Hz or 6000 ERPM (8 Cylinder Engine) 20090612 Current Driven Meter Indicating Engine RPM IO = 10 mA @ 300 Hz or 6000 ERPM (6 Cylinder Engine) 20090613 www.national.com 10 LM2907EP/LM2917EP Enhanced Plastic Typical Applications (Continued) Capacitance Meter VOUT = 1V–10V for CX = 0.01 to 0.1 mFd (R = 111k) 20090614 Two-Wire Remote Speed Switch 20090615 11 www.national.com LM2907EP/LM2917EP Enhanced Plastic Typical Applications (Continued) 100 Cycle Delay Switch 20090616 Variable Reluctance Magnetic Pickup Buffer Circuits 20090639 Precision two-shot output frequency equals twice input frequency. 20090617 Pulse height = VZENER www.national.com 12 LM2907EP/LM2917EP Enhanced Plastic Typical Applications Finger Touch or Contact Switch (Continued) 20090619 20090618 Flashing LED Indicates Overspeed 20090620 Flashing begins when fIN ≥ 100 Hz. Flash rate increases with input frequency increase beyond trip point. 13 www.national.com LM2907EP/LM2917EP Enhanced Plastic Typical Applications (Continued) Frequency to Voltage Converter with 2 Pole Butterworth Filter to Reduce Ripple 20090621 Overspeed Latch 20090623 20090622 www.national.com 14 LM2907EP/LM2917EP Enhanced Plastic Typical Applications (Continued) Some Frequency Switch Applications May Require Hysteresis in the Comparator Function Which can be Implemented in Several Ways: 20090624 20090625 20090626 20090627 20090628 15 www.national.com LM2907EP/LM2917EP Enhanced Plastic Typical Applications (Continued) Changing the Output Voltage for an Input Frequency of Zero 20090630 20090629 Changing Tachometer Gain Curve or Clamping the Minimum Output Voltage 20090632 20090631 www.national.com 16 LM2907EP/LM2917EP Enhanced Plastic Anti-Skid Circuit Functions “Select-Low” Circuit 20090634 VOUT is proportional to the lower of the two input wheel speeds. 20090633 “Select-High” Circuit 20090636 VOUT is proportional to the higher of the two input wheel speeds. 20090635 “Select-Average” Circuit 20090637 17 www.national.com LM2907EP/LM2917EP Enhanced Plastic Equivalent Schematic Diagram 20090638 *This connection made on LM2907-8EP and LM2917-8EP only. **This connection made on LM2917EP and LM2917-8EP only. www.national.com 18 LM2907EP/LM2917EP Enhanced Plastic Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC NS Package Number M08A 14-Lead Molded SO Package NS Package Number M14A 19 www.national.com LM2907EP/LM2917EP Enhanced Plastic Physical Dimensions inches (millimeters) unless otherwise noted (Continued) Molded Dual-In-Line Package (N) NS Package Number N08E Molded Dual-In-Line Package (N) NS Package Number N14A www.national.com 20 LM2907EP/LM2917EP Enhanced Plastic Frequency to Voltage Converter Notes LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. 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