The AD7740YRTZ-REEL7 is a low-cost, ultrasmall synchronous Voltage-to-FrequencyConverter (VFC). It works from a single 3.0 V to3.6 V or 4.75 V to 5.25 V supply consuming 0.9 mA. The AD7740is available in an 8-lead SOT-23 and also in an 8-lead MSOPpackage. Small package, low cost and ease of use were majordesign goals for this product. The part contains an on-chip 2.5 Vbandgap reference but the user may overdrive this using anexternal reference. This external reference range includes VDD.
The full-scale output frequency is synchronous with the clocksignal on the CLKIN pin. This clock can be generated with theaddition of an external crystal (or resonator) or supplied from aCMOS-compatible clock source. The part has a maximuminput frequency of 1 MHz.
For an analog input signal that goes from 0 V to VREF, the outputfrequency goes from 10% to 90% of fCLKIN. In buffered mode,the part provides a very high input impedance and accepts arange of 0.1 V to VDD – 0.2 V on the VIN pin. There is alsoan unbuffered mode of operation that allows VIN to go from–0.15 V to VDD + 0.15 V. The modes are interchangeable usingthe BUF pin.
The AD7740YRTZ-REEL7 (Y Grade) is guaranteed over the automotivetemperature range of –40°C to +105°C. The AD7740YRTZ-REEL7 (K Grade)is guaranteed from 0°C to 85°C.
Product Highlights
The AD7740YRTZ-REEL7 is a single channel, single-ended VFC. It isavailable in 8-lead SOT-23 and 8-lead MSOP packages, and isintended for low-cost applications. The AD7740YRTZ-REEL7 offersconsiderable space saving over alternative solutions.
The AD7740YRTZ-REEL7 operates from a single 3.0 V to 3.6 V or 4.75 Vto 5.25 V supply and consumes typically 0.9 mA when theinput is unbuffered. It also contains an automatic power-downfunction.
The AD7740YRTZ-REEL7 does not require external resistors and capacitorsto set the output frequency. The maximum outputfrequency is set by a crystal or a clock. No trimming or calibrationis required.
The analog input can be taken to 150 mV below GND fortrue bipolar operation.
The specified voltage reference range on REFIN is from2.5 V to the supply voltage, VDD.
Feature
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
Applications
Catalogue
FPGA / CPLD
Memory
MOS 
MCU 
DSP
OCEP
Secondary 
Other 
