LOG114 LOGARITHMIC AMPLIFIER IC Chip

LOG114（Single-Supply, High-Speed, Precision,LOGARITHMIC AMPLIFIER）

Introduction

The LOG114 is specifically designed for measuring low-level and wide dynamic range currents in communications,lasers, medical, and industrial systems. The device computes the logarithm or log-ratio of an input current or voltage relative to a reference current or voltage (logarithmic transimpedance amplifier).

The circuitry on-chip includes special temperature drift compensation, ensuring high precision over a wide dynamic range of input signals on either bipolar (±5V) or single (+5V) supply.In log-ratio applications, the signal current may be from a high impedance source such as a photodiode or resistor in series with a low impedance voltage source. The reference current is provided by a resistor in series with a precision internal voltage reference, photo diode, or active current source.

The output signal at V_LOGOUT has a scale factor of 0.375V out per decade of input current, which limits the output so that it fits within a 5V or 10V range. One of the available additional amplifiers can scale and offset the output, matching it to a wide variety of ADC input ranges. Stable dc performance allows accurate measurement of low-level signals over a wide temperature range. The LOG114 is specified over a -5°C to +75°C temperature range and can operate from -40°C to +85°C.

Feature

• ADVANTAGES:
  – Tiny for High Density Systems
  – Precision on One Supply
  – Fast Over Eight Decades
  – Fully-Tested Function
• TWO SCALING AMPLIFIERS
• WIDE INPUT DYNAMIC RANGE:Eight Decades, 100pA to 10mA
• 2.5V REFERENCE
• STABLE OVER TEMPERATURE
• LOW QUIESCENT CURRENT: 10mA 
• DUAL OR SINGLE SUPPLY: ±5V, +5V
• PACKAGE: Small QFN-16 (4mm x 4mm)
• SPECIFIED TEMPERATURE RANGE:-5°C to +75°C

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