Low Cost Monolithic a Voltage-to-Frequency Converter AD654 FUNCTIONAL BLOCK DIAGRAM FEATURES Low Cost Single or Dual Supply, 5 V to 36 V, 65 V to 618 V C V +V C S T T S Full-Scale Frequency Up to 500 kHz 8 7 6 5 Minimum Number of External Components Needed Versatile Input Amplifier DRIVER OSC Positive or Negative Voltage Modes Negative Current Mode High Input Impedance, Low Drift AD654 Low Power: 2.0 mA Quiescent Current Low Offset: 1 mV 1 2 3 4 LOGIC +V F R IN OUT T COMMON PRODUCT DESCRIPTION 2. A minimum number of low cost external components are The AD654 is a monolithic V/F converter consisting of an input necessary. A single RC network is all that is required to set amplifier, a precision oscillator system, and a high current output up any full scale frequency up to 500 kHz and any full-scale stage. A single RC network is all that is required to set up any input voltage up to 30 V. full scale (FS) frequency up to 500 kHz and any FS input voltage 3. Plastic packaging allows low cost implementation of the up to 30 V. Linearity error is only 0.03% for a 250 kHz FS, standard VFC applications: A/D conversion, isolated signal and operation is guaranteed over an 80 dB dynamic range. The transmission, F/V conversion, phase-locked loops, and tuning overall temperature coefficient (excluding the effects of external switched-capacitor filters. components) is typically 50 ppm/ C. The AD654 operates from 4. Power supply requirements are minimal only 2.0 mA of a single supply of 5 V to 36 V and consumes only 2.0 mA quies- quiescent current is drawn from the single positive supply cent current. from 4.5 volts to 36 volts. In this mode, positive inputs can The low drift (4 m V/ C typ) input amplifier allows operation vary from 0 volts (ground) to (+V 4) volts. Negative inputs S directly from small signals such as thermocouples or strain gauges can easily be connected for below ground operation. while offering a high (250 MW ) input resistance. Unlike most 5. The versatile open-collector output stage can sink more than V/F converters, the AD654 provides a square-wave output, and 10 mA with a saturation voltage less than 0.4 volts. The Logic can drive up to 12 TTL loads, optocouplers, long cables, or Common terminal can be connected to any level between similar loads. ground (or V ) and 4 volts below +V . This allows easy S S direct interface to any logic family with either positive or PRODUCT HIGHLIGHTS negative logic levels. 1. Packaged in both an 8-lead mini-DIP and an 8-lead SOIC package, the AD654 is a complete V/F converter requiring only an RC timing network to set the desired full-scale fre- quency and a selectable pull-up resistor for the open-collector output stage. Any full scale input voltage range from 100 mV to 10 volts (or greater, depending on +V ) can be accommo- S dated by proper selection of the timing resistor. The full- scale frequency is then set by the timing capacitor from the simple relationship, f = V/10 RC. REV. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. use, nor for any infringements of patents or other rights of third parties Tel: 781/329-4700 World Wide Web Site: (T = +258C and V (total) = 5 V to 16.5 V, unless otherwise noted. All testing done A S V = +5 V.) AD654SPECIFICATIONS S AD654JN/JR Model Min Typ Max Units CURRENT-TO-FREQUENCY CONVERTER Frequency Range 0 500 kHz 1 Nonlinearity f = 250 kHz 0.06 0.1 % MAX f = 500 kHz 0.20 0.4 % MAX Full-Scale Calibration Error C = 390 pF, I = 1.000 mA 10 +10 % IN vs. Supply (f 250 kHz) MAX V = +4.75 V to +5.25 V 0.20 0.40 %/V S V = +5.25 V to +16.5 V 0.05 0.10 %/V S vs. Temp (0 C to +70 C) 50 ppm/ C ANALOG INPUT AMPLIFIER (Voltage-to-Current Converter) Voltage Input Range Single Supply 0 (+V 4) V S Dual Supply V (+V 4) V S S Input Bias Current (Either Input) 30 50 nA Input Offset Current 5 nA Input Resistance (Noninverting) 250 MW Input Offset Voltage 0.5 1.0 mV vs. Supply V = +4.75 V to +5.25 V 0.1 0.25 mV/V S V = +5.25 V to +16.5 V 0.03 0.1 mV/V S vs. Temp (0 C to +70 C) 4 m V/ C OUTPUT INTERFACE (Open Collector Output) (Symmetrical Square Wave) 2 Output Sink Current in Logic 0 V = 0.4 V max, +25 C 10 20 mA OUT = 0.4 V max, 0 C to +70 C5 10 mA V OUT Output Leakage Current in Logic 1 10 100 nA 0 C to +70 C 50 500 nA Logic Common Level Range V (+V 4) V S S Rise/Fall Times (C = 0.01 m F) T = 1 mA 0.2 m s I IN I = 1 mA1 m s IN POWER SUPPLY Voltage, Rated Performance 4.5 16.5 V Voltage, Operating Range Single Supply 4.5 36 V Dual Supply 5 18 V Quiescent Current V (Total) = 5 V 1.5 2.5 mA S V (Total) = 30 V 2.0 3.0 mA S TEMPERATURE RANGE Operating Range 40 +85 C NOTES 1 At f = 250 kHz R = 1 kW , C = 390 pF, I = 0 mA1 mA. MAX T T IN 1 At f = 500 kHz R = 1 kW , C = 200 pF, I = 0 mA1 mA. MAX T T IN 2 The sink current is the amount of current that can flow into Pin 1 of the AD654 while maintaining a maximum voltage of 0.4 V between Pin 1 and Logic Common. Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and max specifications are guaranteed, although only those shown in boldface are tested on all production units. Specifications subject to change without notice. C 2 REV.