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 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. 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.

• 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

• 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
• Dynamic range (Typ) (dB)
• 160
• 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

LOG114的完整型号有：LOG114AIRGVR、LOG114AIRGVT，以下是这些产品的关键参数及官网采购报价：

LOG114AIRGVR，工作温度：0 to 70，封装：VQFN (RGV)-16，包装数量MPQ：2500个，MSL 等级/回流焊峰值温度：Level-2-260C-1 YEAR，引脚镀层/焊球材料：NIPDAU，TI官网LOG114AIRGVR的批量USD价格：4.574（1000+）

LOG114AIRGVT，工作温度：0 to 70，封装：VQFN (RGV)-16，包装数量MPQ：250个，MSL 等级/回流焊峰值温度：Level-2-260C-1 YEAR，引脚镀层/焊球材料：NIPDAU，TI官网LOG114AIRGVT的批量USD价格：5.445（1000+）

LOG114EVM — LOG114 评估模块

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 (...)

LOG114 PSpice Model (Rev. C)

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TINA-TI — 基于 SPICE 的模拟仿真程序

TINA-TI 提供了 SPICE 所有的传统直流、瞬态和频域分析以及更多。TINA 具有广泛的后处理功能，允许您按照希望的方式设置结果的格式。虚拟仪器允许您选择输入波形、探针电路节点电压和波形。TINA 的原理图捕获非常直观 - 真正的“快速入门”。

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需要 HSpice (...)