AD7740 3 V/5 V Low Power, Synchronous Voltage-to-Frequency Converter

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. 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. 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. The analog input can be taken to 150 mV below GND for true bipolar operation. The specified voltage reference range on REFIN is from 2.5 V to the supply voltage, VDD.

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

Applications

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
  • Analog to Digital Converters
    Data Sheets
    Documentnote
    AD7740: 3 V/5 V Low Power, Synchronous Voltage-to-Frequency Converter Data Sheet (Rev. C)PDF 246.61 K
    Application Notes
    Documentnote
    AN-214: Ground Rules for High Speed CircuitsPDF 356 kB
    AN-349: Keys to Longer Life for CMOSPDF 89 kB
    AN-276: Analog to Digital Conversion by Using V/F ConvertersPDF 646 kB
    Frequently Asked Questions
    Documentnote
    Order Information
    Part NumberPackagePacking QtyTemp RangePrice 100-499Price 1000+RoHS
    AD7740KRM Last Time Buy8 ld MSOPOTH 500 to 85C00N
    AD7740KRMZ Production8 ld MSOPOTH 500 to 85C1.070.91Y
    AD7740KRMZ-REEL Production8 ld MSOPREEL 30000 to 85C00.91Y
    AD7740KRMZ-REEL7 Production8 ld MSOPREEL 10000 to 85C00.91Y
    AD7740YRM Production8 ld MSOPOTH 50-40 to 105C00N
    AD7740YRMZ Production8 ld MSOPOTH 50-40 to 105C1.321.12Y
    AD7740YRMZ-REEL Production8 ld MSOPREEL 3000-40 to 105C01.12Y
    AD7740YRMZ-REEL7 Production8 ld MSOPREEL 1000-40 to 105C01.12Y
    AD7740YRTZ-REEL7 Production8 ld SOT-23REEL 3000-40 to 105C01.12Y
    AD7740: 3 V/5 V Low Power, Synchronous Voltage-to-Frequency Converter Data Sheet (Rev. C) ad7740
    AN-214: Ground Rules for High Speed Circuits ad1674
    AN-349: 延长CMOS寿命的关键因素 adg3233
    AN-349: Keys to Longer Life for CMOS ad7703
    AN-276: Analog to Digital Conversion by Using V/F Converters ad537