AD7740KRMZ-REEL

Overview

The AD7740KRMZ-REEL is a synchronous Voltage-to-Frequency Converter (VFC) from Analog Devices, housed in an 8-lead MSOP package. It operates on a single supply ranging from 3.0 V to 5.25 V with typical current consumption of 0.9 mA. The device features an internal 2.5 V reference and supports a maximum input frequency of 1 MHz. Integral Nonlinearity is specified at ±0.012% FSR in unbuffered mode. The K-grade variant guarantees operation within a temperature range of 0 °C to +85 °C.

Feature Summary

• Synchronous operation where full-scale output frequency is defined by the external system clock signal applied to CLKIN.
• True bipolar input capability allowing analog signals down to –150 mV without requiring a charge pump circuit.
• Integrated automatic power-down function that activates when the clock input remains inactive low for approximately 1 ms.

Applications

• Low-cost analog-to-digital conversion systems utilizing pulse counting techniques
• Isolation of high common-mode voltages using opto-isolators
• Battery monitoring applications requiring ratiometric measurement
• Automotive sensing environments

Procurement Notes

Verify the specific suffix REEL against the manufacturer's ordering guide to confirm tape-and-reel packaging configuration. Ensure the K grade designation matches the required commercial temperature range of 0 °C to +85 °C rather than the automotive Y grade. Confirm RoHS compliance status as indicated by the Z suffix if applicable to your assembly requirements.

Selection Notes

Select this component for designs prioritizing minimal external component count and space efficiency. The choice between buffered and unbuffered modes depends on source impedance and whether negative voltage inputs are necessary. Consider the stability of the external clock source or crystal oscillator, as the device's accuracy relies directly on the CLKIN frequency stability.

Part Context

This part belongs to the AD7740 family of ultrasmall, low-cost synchronous VFCs. It shares functional characteristics with other variants such as the AD7740YRMZ, differing primarily in temperature rating and package type. The series is designed to replace traditional asynchronous VFC solutions by eliminating external timing capacitors.

Replacement Considerations

AD7740KRMZ

FAQ

How does the BUF pin affect the analog input voltage range?

When the BUF pin is tied low, the device operates in unbuffered mode, accepting an input range from –0.15 V to VDD + 0.15 V. When tied high, it enters buffered mode, restricting the input range to 0.1 V to VDD – 0.2 V while providing high input impedance.

What determines the full-scale output frequency of the AD7740?

Unlike asynchronous converters, the AD7740's full-scale frequency is set synchronously by the master clock signal applied to the CLKIN pin. The output frequency spans from 10% to 90% of the CLKIN frequency based on the analog input voltage.