AD654JNZ

The AD654JNZ is one member of the AD654 series.The AD654 is a monolithic V/F converter consisting of an input amplifier, a precision oscillator system, and a high current output stage. A single RC network is all that is required to set up any full scale (FS) frequency up to 500 kHz and any FS input voltage up to30 V. Linearity error is only 0.03% for a 250 kHz FS,and operation is guaranteed over an 80 dB dynamic range.The overall temperature coefficient (excluding the effects of external components) is typically50 ppm/ C.The AD654 operates from a single supply of 5 V to 36 V and consumes only 2.0 mA quiescent current.

Features of the AD654JNZ are:(1)low cost; (2)single or dual supply, 5 V to 36 V, 65 V to 618 V; (3)full-scale frequency up to 500 kHz; (4)minimum number of external components needed; (5)versatile input amplifier:positive or negative voltage modes,negative current mode,high input impedance, low drift; (6)low power: 2.0 mA quiescent current; (7)low offset: 1 mV.The low drift (4 m V/ C typ) input amplifier allows operation directly from small signals such as thermocouples or strain gauges while offering a high (250 MW ) input resistance. Unlike most V/F converters, the AD654 provides a square-wave output, and can drive up to 12 TTL loads, optocouplers, long cables, or similar loads.

The absolute maximum ratings of the AD654JNZ can be summarized as:(1)total supply voltage +VS toVS:36 V;(2)maximum input voltage toVS:300 mV to +VS;(3)maximum output current instantaneous:50 mA;(4)storage temperature range:65 to +150;(5)logic common toVS:500 mV to (+VS-4).Full-scale trim is the calibration of the circuit to produce the desired output frequency with a full-scale input applied. In most cases this is accomplished by adjusting the scaling resistor RT.Precise calibration of the AD654 requires the use of an accurate voltage standard set to the desired FS value and an accurate frequency meter. A scope is handy for monitoring output waveshape.Verification of converter linearity requires the use of a switchable voltage source or DAC having a linearity error below0.005%, and the use of long measurement intervals to minimize count uncertainties.