Datasheet AD652 (Analog Devices)

Monolithic Synchronous Voltage-to-Frequency Converter AD652 FEATURES
The AD652 is available in five performance grades. The 20-lead
Full-scale frequency (up to 2 MHz) set by external system
PLCC-packaged JP and KP grades are specified for operation
clock
over the 0°C to +70°C commercial temperature range. The
Extremely low linearity error (0.005% max at 1 MHz FS,
16-lead CERDIP-packaged AQ and BQ grades are specified for
0.02% max at 2 MHz FS)
operation over the −40°C to +85°C industrial temperature
No critical external components required
range. The AD652SQ is available for operation over the full
Accurate 5 V reference voltage
−55°C to +125°C extended temperature range.
Low drift (25 ppm/
°
C max) Dual- or single-supply operation PRODUCT HIGHLIGHTS Voltage or current input
1. The use of an external clock to set the full-scale frequency
MIL-STD-883 compliant versions available
allows the AD652 to achieve linearity and stability far superior to other monolithic VFCs. By using the same clock
PRODUCT DESCRIPTION
to drive the AD652 and set the counting period (through a The AD652 synchronous voltage-to-frequency converter suitable divider), conversion accuracy is maintained (SVFC) is a powerful building block for precision analog-to- independent of variations in clock frequency. digital conversion, offering typical nonlinearity of 0.002% 2. The AD652 synchronous VFC requires only one external (0.005% maximum) at a 100 kHz output frequency. The inher- component (a noncritical integrator capacitor) for ent monotonicity of the transfer function and wide range of operation. clock frequencies allow the conversion time and resolution to be optimized for specific applications. 3. The AD652 includes a buffered, accurate 5 V reference. The AD652 uses a variation of the charge-balancing technique 4. The AD652’s clock input is TTL and CMOS compatible and to perform the conversion function. The AD652 uses an can also be driven by sources referred to the negative power external clock to define the full-scale output frequency, rather supply. The flexible open-collector output stage provides than relying on the stability of an external capacitor. The result sufficient current sinking capability for TTL and CMOS is a more stable, more linear transfer function, with significant logic, as well as for optical couplers and pulse transformers. application benefits in both single- and multichannel systems. A capacitor-programmable one-shot is provided for selec- tion of optimum output pulse width for power reduction. Gain drift is minimized using a precision low drift reference 5. The AD652 can also be configured for use as a synchronous and low TC, on-chip, thin-film scaling resistors. Furthermore, F/V converter for isolated analog signal transmission. initial gain error is reduced to less than 0.5% by the use of laser- wafer-trimming. 6. The AD652 is available in versions compliant with MILSTD-883. Refer to the Analog Devices Military The analog and digital sections of the AD652 have been Products Databook or current AD652/883B data sheet for designed to allow operation from a single-ended power source, detailed specifications. simplifying its use with isolated power supplies.
FUNCTIONAL BLOCK DIAGRAM CLOCK IN RIN COMPARATOR CINT V D FLOP LATCH IN CK G ONE Q SHOT AND D Q D Q INTEGRATOR COS 5V H L 1mA –VS
00798-001 Figure 1.
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Document Outline FEATURES PRODUCT DESCRIPTION PRODUCT HIGHLIGHTS FUNCTIONAL BLOCK DIAGRAM SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION DEFINITIONS OF SPECIFICATIONS THEORY OF OPERATION OVERRANGE SVFC CONNECTION FOR DUAL SUPPLY, POSITIVE INPUT VOLTAGES SVFC CONNECTIONS FOR NEGATIVE INPUT VOLTAGES SVFC CONNECTION FOR BIPOLAR INPUT VOLTAGES PLCC CONNECTIONS GAIN AND OFFSET CALIBRATION GAIN PERFORMANCE REFERENCE NOISE DIGITAL INTERFACING CONSIDERATIONS COMPONENT SELECTION DIGITAL GROUND SINGLE-SUPPLY OPERATION FREQUENCY-TO-VOLTAGE CONVERTER DECOUPLING AND GROUNDING FREQUENCY OUTPUT MULTIPLIER SINGLE-LINE MULTIPLEXED DATA TRANSMISSION Multiplexer Transmitter SVFC Demultiplexer Analog Signal Reconstruction ISOLATED FRONT END A-TO-D CONVERSION DELTA MODULATOR BRIDGE TRANSDUCER INTERFACE OUTLINE DIMENSIONS ORDERING GUIDE