Description

The MAX4207 logarithmic amplifier computes the logratio of an input current relative to a reference current(externally or internally generated) and provides a correspondingvoltage output with a default -0.25V/decadescale factor. The device operates from dual ±2.7V to±5.5V supplies and is capable of measuring fivedecades of input current across a 10nA to 1mA range.The MAX4207's uncommitted op amp can be used fora variety of functions, including filtering noise, addingoffset, and adding additional gain. A 0.5V reference isalso included to generate an optional precision currentreference using an external resistor, which adjusts thelog intercept of the MAX4207. The output-offset voltageand the adjustable scale factor are also set using externalresistors.The MAX4207 is available in a space-saving 16-pin thinQFN package (4mm x 4mm x 0.8mm), and is specifiedfor operation over the -40°C to +85°C extended temperaturerange.ApplicationsAnalog Signal ProcessingMedical InstrumentationPhotodiode Current MonitoringPortable Instrumentation