The MAX4207 logarithmic amplifier computes the log
ratio of an input current relative to a reference current
(externally or internally generated) and provides a corresponding
voltage output with a default -0.25V/decade
scale factor. The device operates from dual ±2.7V to
±5.5V supplies and is capable of measuring five
decades of input current across a 10nA to 1mA range.
The MAX4207's uncommitted op amp can be used for
a variety of functions, including filtering noise, adding
offset, and adding additional gain. A 0.5V reference is
also included to generate an optional precision current
reference using an external resistor, which adjusts the
log intercept of the MAX4207. The output-offset voltage
and the adjustable scale factor are also set using external
resistors.
The MAX4207 is available in a space-saving 16-pin thin
QFN package (4mm x 4mm x 0.8mm), and is specified
for operation over the -40°C to +85°C extended temperature
range.
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