AD7740

a FEATURES Synchronous Operation Full-Scale Frequency Set by External System Clock 8-Lead SOT-23 and 8-Lead microSOIC Packages 3 V or 5 V Operation Low Power: 3 mW (Typ) Nominal Input Range: 0 to VREF True –150 mV Capability Without Charge Pump VREF Range: 2.5 V to VDD Internal 2.5 V Reference 1 MHz Max Input Frequency Selectable High Impedance Buffered Input Minimal External Components Required APPLICATIONS Isolation of High Common-Mode Voltages Low-Cost Analog-to-Digital Conversion Battery Monitoring Automotive Sensing 3 V/5 V Low Power, Synchronous Voltage-to-Frequency Converter AD7740* FUNCTIONAL BLOCK DIAGRAM REFIN/OUT VDD AD7740 2.5V REFERENCE VIN X1 VOLTAGE-TOFREQUENCY MODULATOR FOUT CLOCK GENERATION BUF GND CLKOUT CLKIN GENERAL DESCRIPTION The AD7740 is a low-cost, ultrasmall synchronous Voltage-toFrequency Converter (VFC). It works from a single 3.0 V to 3.6 V or 4.75 V to 5.25 V supply consuming 0.9 mA. The AD7740 is available in an 8-lead SOT-23 and also in an 8-lead microSOIC package. Small package, low cost and ease of use were major design goals for this product. The part contains an on-chip 2.5 V bandgap reference but the user may overdrive this using an external reference. This external reference range includes VDD. The full-scale output frequency is synchronous with the clock signal on the CLKIN pin. This clock can be generated with the addition of an external crystal (or resonator) or supplied from a CMOS-compatible clock source. The part has a...