LOG102

Features:

· EASY-TO-USE COMPLETE LOG RATIO FUNCTION
· OUTPUT AMPLIFIERS FOR SCALING AND SIGNAL LOSS INDICATION
· HIGH ACCURACY: 0.15% FSO Total Error Over 6 Decades
· WIDE INPUT DYNAMIC RANGE: 6 Decades, 1nA to 1mA
· LOW QUIESCENT CURRENT: 1.25mA
· SO-14 PACKAGE


Application

· ONET, OPTICAL POWER METERS
· LOG, LOG RATIO COMPUTATION: Communication, Analytical, Medical, Industrial, Test, General Instrumentation
· PHOTODIODE SIGNAL COMPRESSION AMP
· ANALOG SIGNAL COMPRESSION IN FRONT OF A/D CONVERTER
· ABSORBANCE MEASUREMENT
· OPTICAL DENSITY MEASUREMENT


Specifications

Supply Voltage, V+ to V ...................................... 36V
Input Voltage .......................... V (0.5) to V+ (+0.5V)
Input Current .................................................... ±10mA
Output Short-Circuit(2) ................................ Continuous
Operating Temperature ..........................40 to +85
Storage Temperature ............................55 to +125
Junction Temperature .......................................... +150
Lead Temperature (soldering, 10s) .......................+300

Description

The LOG102 is a versatile integrated circuit that computes the logarithm or log ratio of an input current relative to a reference current.

The LOG102 is tested over a wide dynamic range of input signals. In log ratio applications, a signal current can be generated by a photodiode, and a reference current from a resistor in series with a precision external voltage reference.

A3 and A4 are identical, uncommitted op amps that can be used for a variety of functions, such as filtering, offsetting, adding gain or as a comparator to detect loss of signal.

The output signal at VLOG OUT is trimmed to 1V per decade of input current. It can be scaled with an output amplifier, either A3 or A4.

Low dc offset voltage and temperature drift allow accurate measurement of low-level signals over a wide environmental temperature range. The LOG102 is specified over the temperature range, 0°C to +70, with operation over 40 to +85.