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Product details

Parameters

Scale factor (V/decade) 0.375 Input current range (Min) (nA) 0.1 Input current range (Max) (mA) 10 Conformity error (initial 5 decades) (Max) (%) 0.2 Conformity error (initial 5 decades) (typ. over temp) (%/degree C) 0.1 Offset voltage (input amplifiers) (Max) (mV) 4 Vs (+/-) (Min) (V) 4.8 Vs (+/-) (Max) (V) 11 Iq (Max) (mA) 15 Reference type Internal Auxiliary op amps 2 Full-scale output voltage (Min) (+/- V) -4.4 Full-scale output voltage (Max) (+/- V) 4.4 Operating temperature range (C) 0 to 70 Specified voltage (+/- V) 5 open-in-new Find other Logarithmic amplifiers

Package | Pins | Size

VQFN (RGV) 16 16 mm² 4 x 4 open-in-new Find other Logarithmic amplifiers

Features

  • 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
  • STABILE 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
  • APPLICATIONS
    • ONET ERBIUM-DOPED FIBER OPTIC AMPLIFIER (EDFA)
    • LASER OPTICAL DENSITY MEASUREMENT
    • PHOTODIODE SIGNAL COMPRESSION AMP
    • LOG, LOG-RATIO FUNCTION
    • ANALOG SIGNAL COMPRESSION IN FRONT OF ANALOG-TO-DIGITAL (ADC) CONVERTER
    • ABSORBANCE MEASUREMENT

All trademarks are the property of their respective owners.

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Description

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).

High precision is ensured over a wide dynamic range of input signals on either bipolar (±5V) or single (+5V) supply. Special temperature drift compensation circuitry is included on-chip. 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 VLOGOUT 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. The output can be scaled and offset with one of the available additional amplifiers, so it matches 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.

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Technical documentation

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Type Title Date
* Datasheet Single-Supply, High-Speed, Precision Logarithmic Amplifier datasheet (Rev. A) Mar. 19, 2007
User guides LOG114EVM User Guide Sep. 29, 2011
More literature Log Amp Basics Part 2: Design Example for LOG114 [WMV] Feb. 19, 2010

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Hardware development

EVALUATION BOARDS Download
document-generic User guide
$49.00
Description

The LOG114EVM is a ready-to-use platform for evaluating the performance of the LOG114 in various configurations.The LOG114EVM comes configured to operate on a single 5-V power supply. The circuit used in the LOG114EVM is designed to operate over a wide range of input currents (10 nA to 10 mA) and (...)

Features
  • Easy to use
  • High Speed + Precision
  • Wide Input Dynamic Range
  • Operates on a single 5V supply
  • PCB footprint provided for photo diode or resistor input

Design tools & simulation

SIMULATION MODELS Download
SBOM383C.ZIP (53 KB) - PSpice Model
SIMULATION MODELS Download
SBOM384C.TSC (101 KB) - TINA-TI Reference Design
SIMULATION MODELS Download
SBOM385C.ZIP (5 KB) - TINA-TI Spice Model
SIMULATION TOOLS Download
SPICE-based analog simulation program
TINA-TI TINA-TI provides all the conventional DC, transient and frequency domain analysis of SPICE and much more. TINA has extensive post-processing capability that allows you to format results the way you want them. Virtual instruments allow you to select input waveforms and probe circuit nodes voltages (...)
document-generic User guide

CAD/CAE symbols

Package Pins Download
VQFN (RGV) 16 View options

Ordering & quality

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