●Product Details
●The AD7740 is a low-cost, ultrasmall synchronous Voltage-to-Frequency 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 MSOP 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 maximum input frequency of 1 MHz.
●For an analog input signal that goes from 0 V to VREF, the output frequency goes from 10% to 90% of fCLKIN. In buffered mode, the part provides a very high input impedance and accepts a range of 0.1 V to VDD – 0.2 V on the VIN pin. There is also an unbuffered mode of operation that allows VIN to go from –0.15 V to VDD + 0.15 V. The modes are interchangeable using the BUF pin.
●The AD7740 (Y Grade) is guaranteed over the automotive temperature range of –40°C to +105°C. The AD7740 (K Grade) is guaranteed from 0°C to 85°C.
●Product Highlights
● 1. The AD7740 is a single channel, single-ended VFC. It is available in 8-lead SOT-23 and 8-lead MSOP packages, and is intended for low-cost applications. The AD7740 offers considerable space saving over alternative solutions.
● 2. The AD7740 operates from a single 3.0 V to 3.6 V or 4.75 V to 5.25 V supply and consumes typically 0.9 mA when the input is unbuffered. It also contains an automatic power-down function.
● 3. The AD7740 does not require external resistors and capacitors to set the output frequency. The maximum output frequency is set by a crystal or a clock. No trimming or calibration is required.
● 4. The analog input can be taken to 150 mV below GND for true bipolar operation.
● 5. The specified voltage reference range on REFIN is from 2.5 V to the supply voltage, VDD.
●Applications
● Isolation of high common-mode voltages
● Low-cost analog-to-digital conversion
● Battery monitoring
● Automotive sensing
●### Features and Benefits
● Synchronous operation
● Full-scale frequency set by external system clock
● 8-lead SOT-23 and 8-lead MSOP 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
