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LM2907/LM2917 Frequency to Voltage Converter June 2000 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…show more content…
Electrical Characteristics VCC = 12 VDC, TA = 25˚C, see test circuit Symbol TACHOMETER Input Thresholds Hysteresis Offset Voltage LM2907/LM2917 LM2907-8/LM2917-8 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 = 1.0 VE = VCC −2.0 ISINK = 5 mA ISINK = 20 mA ISINK = 50 mA ZENER REGULATOR Regulator Voltage Series Resistance Temperature Stability TOTAL SUPPLY CURRENT RDROP = 470Ω 7.56 10.5 +1 3.8 6 15 V Ω mV/˚C mA 1.0 40 VIN = 6.0V VIN = 6.0V 0 200 50 10 0.1 0.5 1.0 1.5 3 50 10 500 VCC−1.5V mV nA V V/mV mA mA V V V VIN = ± 50 mVDC VIN = +125 mVDC (Note 3) VIN = −125 mVDC (Note 3) V2 = V3 = 6.0V (Note 4) I2 = 0, V3 = 0 (Note 3) fIN = 1 kHz, 5 kHz, 10 kHz (Note 5) 0.9 −1.0 1.0 0.3 140 VIN = 250 mVp-p @ 1 kHz (Note 2) VIN = 250 mVp-p @ 1 kHz (Note 2) VIN = 250 mVp-p @ 1 kHz (Note 2) 3.5 5 0.1 8.3 2.3 180 240 0.1 1.1 +1.0 % 10 15 1 mV mV µA V V µA µA Parameter Conditions Min Typ Max Units mV mV ± 10 ± 25 30 ± 40 Note 1: 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
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