XD2907-8

XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 1 Features 3 Description • The XD2907 and XD2917 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 lowripple, full-input protection in two versions (8-pin XD2907 and XD2917), and its output swings to ground for a zero frequency input. 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 (XD2917) 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. 4 Device Information(1) 2 Applications • • • • • • • • • • • PART NUMBER 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 2917 2907 PACKAGE BODY SIZE (NOM) 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 1 1 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 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 TACH+ 1 8 TACH±/GND CP1 2 7 IN± CP2/IN+ 3 6 V+ EMIT 4 5 COL Not to scale Pin Functions: 8 Pins PIN NAME NO. I/O DESCRIPTION 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 XD2907 and XD2917) 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 — — TACH+ 1 I Positive terminal for the input signal that leads to the noninverting terminal of the internal SchmittTrigger comparator. TACH–/GND 8 I Negative terminal for the input signal that leads to the noninverting terminal of the internal SchmittTrigger comparator. (NOTE: On 8-pin devices, XD2907 and XD2917, 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 No connect 2 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP NFF and D Package 14-Pin PDIP and SOIC Top View TACH+ 1 14 NC CP1 2 13 NC CP2 3 12 GND IN+ 4 11 TACH± EMIT 5 10 IN± NC 6 9 V+ NC 7 8 COL Not to scale Pin Functions: 14 Pins PIN NAME NO. I/O DESCRIPTION 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 — TACH+ 1 I Positive terminal for the input signal that leads to the noninverting terminal of the internal SchmittTrigger comparator. TACH– 11 I Negative terminal for the input signal that leads to the noninverting terminal of the internal SchmittTrigger comparator. V+ 9 I Supply voltage No connect 3 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 7 Specifications 7.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) (2) MAX UNIT Supply voltage MIN 28 V Supply current (Zener options) 25 mA Collector voltage 28 V 28 V Differential input voltage Input voltage Tachometer, op amp, and comparator XD2907 (8), XD2917 (8) Tachometer XD2907 (14), XD2917 (14) Op amp and comparator Power dissipation 28 0 28 0 28 XD29x7 (8) 1200 XD29x7 (14) 1580 PDIP package Soldering information –28 SOIC package Soldering (10 s) 260 Vapor phase (60 s) 215 Infrared (15 s) V mW °C 220 Operating temperature, TJ –40 85 °C Storage temperature, Tstg –65 150 °C (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. 7.2 ESD Ratings VALUE V(ESD) (1) (2) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JESD22-A114 (1) ±1000 Charged-device model (CDM), per JEDEC specification JESD22-C101 (2) ±250 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 7.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN Input voltage XD2907 (8), XD2917 (8) XD2907 (14), XD2917 (14) Output sink current 4 NOM MAX UNIT –28 28 0 28 V V 50 mA XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 7.4 Thermal Information XD2907, XD2917 THERMAL METRIC (1) P (PDIP) D (SOIC) NFF (PDIP) D (SOIC) 8 PINS 8 PINS 14 PINS 14 PINS UNIT 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) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. 7.5 Electrical Characteristics VCC = 12 VDC, TA = 25°C, see test circuit PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ±10 ±25 ±40 mV TACHOMETER Input thresholds VIN = 250 mVp-p at 1 kHz (1) Hysteresis VIN = 250 mVp-p at 1 kHz (1) 30 VIN = 250 mVp-p at 1 kHz (1) 3.5 10 5 15 1 XD29x7 offset voltage VIN = 250 mVp-p at 1 kHz (8-pin XD29x7) (1) Input bias current VIN = ±50 mVDC 0.1 VOH High level output voltage For CP1, VIN = 125 mVDC (2) 8.3 VOL Low level output voltage For CP1, VIN = –125 mVDC (2) 2.3 I2, I3 Output current V2 = V3 = 6 V (3) I3 Leakage current I2 = 0, V3 = 0 K Gain constant See (2) Linearity fIN = 1 kHz, 5 kHz, or 10 kHz (4) mV mV μA V V 140 180 240 μA 0.9 1 0.1 1.1 μA –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 Voltage gain V/mV 50 mA VC = 1 Output source current VE = VCC –2 10 ISINK = 5 mA 0.1 ISINK = 20 mA ISINK = 50 mA V 200 Output sink current Saturation voltage 40 VCC–1.5 1 mA 0.5 V 1 V 1.5 V ZENER REGULATOR Regulator voltage RDROP = 470 Ω 7.56 Series resistance 10.5 Temperature stability (3) (4) 15 1 Total supply current (1) (2) V 3.8 Ω mV/°C 6 mA Hysteresis is the sum VTH – (–VTH), offset voltage is their difference. See test circuit. 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. 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 MΩ typically. 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 kΩ and C2 = 0.22 µF. 5 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 7.6 Typical Characteristics XD2917 XD2917 XD2907 XD2907 Figure 1. Tachometer Linearity vs Temperature Figure 2. Tachometer Linearity vs Temperature Figure 3. Total Supply Current Figure 4. Zener Voltage vs Temperature XD2907 XD2917 XD2907 XD2917 Figure 6. Normalized Tachometer Output (K) vs Temperature Figure 5. Normalized Tachometer Output (K) vs Temperature 6 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP Typical Characteristics (continued) Figure 7. Tachometer Currents I2and I3 vs Supply Voltage Figure 8. Tachometer Currents I2and I3 vs Temperature XD2907 XD2917 Figure 10. Tachometer Input Hysteresis vs Temperature Figure 9. Tachometer Linearity vs R1 XD2907 XD2917 Figure 12. Op Amp Output Transistor Characteristics Figure 11. Op Amp Output Transistor Characteristics 7 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 8 Parameter Measurement Information Figure 13. Test Circuit Figure 14. Tachometer Input Threshold Measurement 8 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 9 Detailed Description 9.1 Overview The XD29x7 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 XD29x7 has the flexibility to be configured a variety of ways to meet system requirements including voltage output, driving loads, operating a relay, and more. 9 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 9.2 Functional Block Diagram 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 XD29x7-8 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 XD29x7 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. 10 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 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 XD2907 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 XD2907 and XD2917) 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 XD2907 and XD2917 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. 11 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 12 11 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 11 13 XD2917-8/XD2907-8/XD2907-14/XD2917-14 DIP XL2907-8/XL2917-8/XL2907-14/XL2917-14 SOP 14 11