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 | Analog to Digital Converters |
Document | note |
AD7740: 3 V/5 V Low Power, Synchronous Voltage-to-Frequency Converter Data Sheet (Rev. C) | PDF 246.61 K |
Document | note |
AN-214: Ground Rules for High Speed Circuits | PDF 356 kB |
AN-349: Keys to Longer Life for CMOS | PDF 89 kB |
AN-276: Analog to Digital Conversion by Using V/F Converters | PDF 646 kB |
Document | note |
Part Number | Package | Packing Qty | Temp Range | Price 100-499 | Price 1000+ | RoHS |
---|---|---|---|---|---|---|
AD7740KRM Last Time Buy | 8 ld MSOP | OTH 50 | 0 to 85C | 0 | 0 | N |
AD7740KRMZ Production | 8 ld MSOP | OTH 50 | 0 to 85C | 1.07 | 0.91 | Y |
AD7740KRMZ-REEL Production | 8 ld MSOP | REEL 3000 | 0 to 85C | 0 | 0.91 | Y |
AD7740KRMZ-REEL7 Production | 8 ld MSOP | REEL 1000 | 0 to 85C | 0 | 0.91 | Y |
AD7740YRM Production | 8 ld MSOP | OTH 50 | -40 to 105C | 0 | 0 | N |
AD7740YRMZ Production | 8 ld MSOP | OTH 50 | -40 to 105C | 1.32 | 1.12 | Y |
AD7740YRMZ-REEL Production | 8 ld MSOP | REEL 3000 | -40 to 105C | 0 | 1.12 | Y |
AD7740YRMZ-REEL7 Production | 8 ld MSOP | REEL 1000 | -40 to 105C | 0 | 1.12 | Y |
AD7740YRTZ-REEL7 Production | 8 ld SOT-23 | REEL 3000 | -40 to 105C | 0 | 1.12 | Y |