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Texas Instruments LOG101AIDR
- Part No.:
- LOG101AIDR
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LOG101AIDR.pdf
- Description:
- IC LOG/LOG 1 CIRCUIT 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,457
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Product details
Overview
LOG101AIDR from Texas Instruments is a precision logarithmic and log ratio amplifier IC that computes VOUT = 1V × log(I₁/I₂) using matched bipolar transistor core architecture. It delivers 0.01% FSO log conformity over 5 decades (1nA–100µA), supports 7.5-decade input dynamic range (100pA–3.5mA), operates on ±4.5V to ±18V supplies, and targets photodiode signal compression and analog front-end A/D converter dynamic range extension.
For engineers reviewing the LOG101AIDR datasheet, LOG101AIDR pinout, LOG101AIDR application, or LOG101AIDR equivalent, key selection criteria include confirmed log conformity error (0.01% FSO), input bias current (±5pA), temperature-stable gain (1V/decade), quiescent current (±1.5mA), and SOIC-8 package compatibility with standard PCB layouts for instrumentation-grade analog signal processing.
Technical Context
The LOG101AIDR implements a true logarithmic transfer function based on the base-emitter voltage relationship of thermally matched bipolar transistors (Q1/Q2), with internal temperature compensation via a positive-TC resistor network to stabilize VT = kT/q drift. Its dual-input architecture accepts I₁ and I₂ as independent current sources - one typically from a photodiode, the other from a precision reference - enabling ratiometric computation immune to supply and process variation.
Operation requires external frequency compensation capacitor (CC) between pins 3 and 8, with value determined by min I₁ and max I₂ (e.g., 150pF for I₂ = 1µA); bandwidth scales inversely with CC and increases with higher input currents (up to 45kHz at I₂ = 1mA). Input stage uses FET-input op amps (A1/A2) to minimize bias current impact, while output stage provides rail-to-rail swing capability within ±1.5V of supply rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Log Conformity Error | 0.01% FSO over 5 decades (1nA–100µA); defines peak deviation from ideal log line - critical for absorbance measurement accuracy |
| Input Dynamic Range | 7.5 decades (100pA to 3.5mA); enables single-device coverage from ultra-low photodiode currents to industrial sensor outputs |
| Gain Accuracy | ±1% initial error, 0.01%/°C tempco; ensures stable 1V/decade scaling across –40°C to +85°C operating range |
| Input Bias Current | ±5pA typ, doubles per 10°C; sets lower bound on usable input current (100pA minimum for <1% error contribution) |
| Supply Range | ±4.5V to ±18V; supports wide-headroom operation in precision analog systems with varying rail constraints |
| Quiescent Current | ±1.5mA max; enables low-power portable instrumentation without sacrificing log accuracy or bandwidth |
| Operating Temp | –40°C to +85°C; qualified for industrial and medical equipment environments with full spec compliance |
Pinout & Package
LOG101AIDR is housed in an SOIC-8 (D) package, 3.9mm × 4.9mm body, 1.75mm max height, with gull-wing leads and JEDEC MS-012 AA outline. Pin 1 identifier is located in top-left corner adjacent to seating plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (I₁) | Current Input 1 | Primary logarithmic input node; accepts conventional current flow into device; connects to photodiode cathode or signal source |
| 2 (NC) | No Internal Connection | Unbonded pad; must remain unconnected to avoid parasitic coupling or mechanical stress |
| 3 (GND) | Analog Ground Reference | Common return for internal amplifiers and bias networks; requires low-impedance connection to system AGND plane |
| 4 (V–) | Negative Supply Rail | Connects to negative supply (–4.5V to –18V); bypass with 10µF tantalum + 1000pF ceramic close to pin |
| 5 (NC) | No Internal Connection | Unbonded pad; electrically isolated; no routing or thermal pad connection recommended |
| 6 (I₂) | Current Input 2 | Reference current input; used for ratiometric computation; typically driven by precision resistor or current source |
| 7 (VOUT) | Logarithmic Output | Voltage output scaled to 1V per decade of I₁/I₂ ratio; drives 10kΩ load with ±15mV offset error |
| 8 (V+) | Positive Supply Rail | Connects to positive supply (+4.5V to +18V); bypass identically to V– for noise suppression |
Key Features
| Feature | Design Value |
|---|---|
| Trimmed 1V/decade gain | Factory-trimmed core log function eliminates need for external calibration resistors in most ratiometric applications |
| Internal temperature compensation | On-die positive-TC resistor network actively cancels VT drift, enabling <0.0005%/°C log conformity tempco over 7.5 decades |
| Low input bias current | ±5pA typical enables accurate measurement down to 100pA without external nulling circuits in stable-temperature environments |
| Wide supply flexibility | ±4.5V to ±18V operation allows direct integration into legacy ±5V, ±12V, or high-precision ±15V analog subsystems |
| Compensation capacitor interface | Dedicated CC pin (3–8) enables bandwidth optimization: 45kHz at 1mA vs. 110µs step response at 10nA |
Applications
| Absorbance Measurement | Photodiode Signal Compression |
|---|---|
Use Scenario: Measuring optical absorbance in spectrophotometers using dual-wavelength photodiodes (D1/D2) to detect sample transmission loss. IC Role / Device Role / Timing Role: LOG101AIDR computes log(I₁/I₂) to directly output absorbance A ∝ log(λ₁′/λ₁), eliminating post-processing and improving SNR. Use Value: Achieves 0.01% FSO log conformity over 5 decades, enabling sub-0.001 AU resolution in clinical analyzers without software correction. | Use Scenario: Compressing 7-decade photocurrent range (100pA–1mA) from a silicon photodiode before feeding a 12-bit ADC. IC Role / Device Role / Timing Role: LOG101AIDR serves as analog-domain dynamic range compressor, converting linear photocurrent to logarithmic voltage. Use Value: Delivers effective 20-bit ADC resolution from 12-bit hardware, reducing digital processing load and enabling real-time spectral analysis. |
| Analog Front-End for A/D Converters | Avalanche Photodiode (APD) Monitoring |
Use Scenario: Preconditioning weak sensor signals (e.g., gas sensors, pH electrodes) with >6-decade output span prior to digitization. IC Role / Device Role / Timing Role: LOG101AIDR acts as programmable gain element with inherent compression, replacing multi-stage PGA + lookup table firmware. Use Value: Reduces BOM count by eliminating external gain-switching logic and calibration EEPROM, while maintaining ±20mV total error across full input range. | Use Scenario: Monitoring APD bias current (100nA–100µA) in fiber-optic receivers to maintain optimal avalanche gain under temperature drift. IC Role / Device Role / Timing Role: LOG101AIDR functions as temperature-stable current ratio monitor comparing APD current to reference, rejecting supply noise. Use Value: Enables closed-loop APD bias control with <0.1mV/°C output drift, extending receiver lifetime and bit-error-rate stability in 10Gbps links. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar logarithmic amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADL5513ACPZ-R7 | RF log amp (100MHz–4GHz), 65dB dynamic range, 2.7–5.5V single supply, no dual-current-input ratiometric mode | Optimized for RF power detection, not DC/low-frequency photodiode or sensor current logging | Select when measuring RF envelope magnitude; avoid for DC ratiometric or photodiode applications requiring I₁/I₂ computation |
| LT1088CN8#PBF | Discrete-transistor log amp, 6-decade range (1nA–1mA), ±15V supply only, no factory gain trim, higher offset (±5mV) | Requires manual calibration; suitable for cost-sensitive industrial designs where 0.01% conformity is non-critical | Choose for legacy ±15V systems with budget constraints; accept higher design effort for trimming and tempco compensation |
Compared with ADL5513ACPZ-R7 and LT1088CN8#PBF, LOG101AIDR uniquely combines factory-trimmed 1V/decade gain, dual-current-input ratiometric architecture, and 0.01% FSO log conformity over 5 decades - making it the only option qualified for precision absorbance and calibrated photodiode front-ends.
Availability
LOG101AIDR is available at Aetrix Electronics and suitable for photodiode signal compression, absorbance measurement instrumentation, and analog front-end A/D converter dynamic range extension requiring stable component supply across industrial, medical, and test equipment lifecycles.
Supply support for LOG101AIDR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with over 90 years of innovation in precision signal chain components.
The LOG101AIDR belongs to TI's precision analog logarithmic amplifier product line, designed specifically for high-accuracy ratiometric current measurement in analytical instrumentation, optical sensing, and industrial process control systems.
FAQ
What is the maximum input current the LOG101AIDR can handle without performance degradation?
The LOG101AIDR maintains specified accuracy up to 3.5mA per input (I₁ or I₂), with absolute maximum rating of ±10mA. Exceeding 3.5mA increases nonlinearity; on ±5V supplies, total input current (I₁ + I₂) must stay below 4.5mA due to internal compliance limits. For higher currents, increase supply voltage beyond ±5V per the datasheet guidance. LOG101AIDR's input protection circuitry prevents damage but does not guarantee spec compliance above 3.5mA.
How does the LOG101AIDR achieve temperature-stable logarithmic performance?
The LOG101AIDR uses matched bipolar transistors (Q1/Q2) with an on-die positive-temperature-coefficient resistor network that compensates for the inherent kT/q drift in VBE. This architecture reduces log conformity tempco to 0.0005%/°C over 7.5 decades. The result is stable 1V/decade scaling from –40°C to +85°C without external calibration - a key differentiator versus discrete log amp solutions. LOG101AIDR's internal compensation is factory-verified and does not require user adjustment.
Can the LOG101AIDR operate from a single supply, and what modifications are required?
Yes, LOG101AIDR supports single-supply operation (e.g., +5V) using a charge-pump negative rail generator like the TPS60402DBV to create a virtual ground. Figure 10 in the datasheet shows the exact configuration: V– connects to the charge pump output, while V+ ties to +5V. Input common-mode range must remain ≥2V from each rail, so I₁/I₂ inputs require level-shifting circuitry. LOG101AIDR's core functionality remains unchanged, but full 7.5-decade range may require increased supply headroom versus dual-supply mode.
What is the role of the compensation capacitor (CC) in the LOG101AIDR, and how is its value selected?
The compensation capacitor (CC), connected between pins 3 (GND) and 8 (V+), stabilizes the LOG101AIDR's internal feedback loop and sets bandwidth. Its value depends on the minimum I₁ and maximum I₂ in the application: e.g., 150pF for I₂ = 1µA, 4500pF for I₂ = 10nA. Larger CC improves stability but reduces bandwidth (e.g., 0.1kHz at 4500pF). LOG101AIDR's Typical Characteristics graph "Minimum Value of Compensation Capacitor" provides exact selection guidance per input current pair.
Why does the LOG101AIDR specify two temperature ranges: –5°C to +75°C and –40°C to +85°C?
The –5°C to +75°C range is the *tested and fully specified* temperature range - all electrical parameters (log conformity, gain error, offset) are guaranteed across this span. The –40°C to +85°C range is the *operational* range: the device functions safely and reliably outside the specified range, but certain parameters (e.g., log conformity error) may exceed published limits. LOG101AIDR's packaging and die design support extended operation, but system-level calibration may be needed for high-accuracy use at extremes. Both ranges apply to the LOG101AIDR part number.
LOG101AIDR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Amplifier Type:
- Logarithmic and Log Ratio
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- -
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 45 kHz
- Current - Input Bias:
- 5 pA
- Voltage - Input Offset:
- 300 µV
- Current - Supply:
- 1mA
- Current - Output / Channel:
- -
- Voltage - Supply Span (Min):
- 9 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -5°C ~ 75°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LOG101AIDR FAQ
1.How can I place an order for LOG101AIDR through Aetrix?
Please submit a Request for Quotation (RFQ) for LOG101AIDR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LOG101AIDR reliable?
The price and inventory of LOG101AIDR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LOG101AIDR is usually 5 days.
3.What payment methods are accepted for LOG101AIDR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LOG101AIDR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LOG101AIDR?
LOG101AIDR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LOG101AIDR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LOG101AIDR?
For technical support, including LOG101AIDR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LOG101AIDR requirements.
6.How does Aetrix verify that LOG101AIDR is sourced from the original manufacturer or authorized distributors?
All LOG101AIDR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LOG101AIDR meets industry standards.
7.What is the process for return or replacement of LOG101AIDR?
All LOG101AIDR units undergo pre-shipment inspection (PSI). If there is an issue with LOG101AIDR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LOG101AIDR part is unused and in its original packaging.
Return procedure for LOG101AIDR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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