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Texas Instruments LOG114AIRGVRG4
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- Part No.:
- LOG114AIRGVRG4
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 16-VQFN Exposed Pad
- Datasheet:
-
LOG114AIRGVRG4.pdf
- Description:
- IC LOGARITHMIC 1 CIRCUIT 16VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,465
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Product details
Overview
LOG114AIRGVRG4 from Texas Instruments is a single-supply, high-speed precision logarithmic amplifier designed for wide-dynamic-range current measurement in optical and laser systems. It computes log(I₁/I₂) with 0.375 V/decade scaling, ±5V or 5V supply operation, and operates across −5°C to 75°C. Its core function enables accurate photodiode current ratio analysis in EDFA control loops.
For engineers reviewing the LOG114AIRGVRG4 datasheet, LOG114AIRGVRG4 pinout, LOG114AIRGVRG4 application, or LOG114AIRGVRG4 equivalent, this page delivers verified specifications, validated QFN-16 pin mapping, real-world optical network use cases, and two confirmed alternative logarithmic amplifiers - all grounded in TI's SBOS301C production data.
Technical Context
The LOG114AIRGVRG4 integrates two matched logarithmic transimpedance amplifiers (A1/A2), a 6.25× differential amplifier (A3), and two auxiliary op-amps (A4/A5). Its on-chip temperature drift compensation ensures stable log-ratio accuracy over −5°C to 75°C, while dual supply support (±5V or 5V) enables flexible system integration.
VLOGOUT delivers a fixed 0.375 V/decade output scale factor referenced to I₁/I₂, with COM pin biasing enabling precise DC offset control. The 2.5V internal bandgap reference (±1% error, ±25 ppm/°C drift) feeds I₂ via external resistor, supporting photodiode-based signal/reference configurations without external references.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Log Scaling Factor | 0.375 V/decade - ensures full-scale VLOGOUT fits within 5V ADC range for 100pA–10mA input ratios |
| Input Dynamic Range | 8 decades (100pA to 10mA) - supports detection of weak photodiode signals alongside strong laser monitor currents |
| Log Conformity Error | 0.3% (typ) over 5 decades - guarantees linearity for optical power ratio measurements in telecom modules |
| Supply Voltage | ±5V or 5V - enables direct compatibility with both bipolar analog front-ends and single-supply embedded systems |
| Reference Voltage | 2.5V ±1% - integrated bandgap source eliminates need for external reference in I₂ generation circuits |
| Operating Temperature | −5°C to 75°C (spec), −40°C to 85°C (operational) - meets industrial-grade thermal requirements for optical terminal units |
| Quiescent Current | ±10 mA (typ) - enables low-power optical monitoring in battery-backed or energy-constrained inter-DC links |
Pinout & Package
LOG114AIRGVRG4 is housed in a thermally enhanced 4mm × 4mm VQFN-16 (RGV) package with exposed thermal pad connected to V−. Pin numbering follows TI's top-view RGV layout; pin 1 is VREFGND, pin 16 is VREF, and the thermal pad must be soldered to a V−-connected copper plane for thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| I1 (Pin 4) | Log numerator current input | Accepts photodiode anode current (100pA–10mA); polarity must be positive into pin |
| I2 (Pin 3) | Log denominator current input | Receives reference current (e.g., from 2.5V/VREF and RREF); enables ratiometric optical power tracking |
| VLOGOUT (Pin 9) | Main logarithmic difference output | Delivers 0.375×log(I₁/I₂) + VCOM; directly interfaces with 12-bit+ SAR ADCs |
| COM (Pin 7) | Differential amplifier common-mode bias | Sets VLOGOUT DC offset; allows output centering at 2.5V for rail-to-rail ADCs |
| VREF (Pin 16) | 2.5V internal reference output | Stable voltage source for generating precision I₂; requires 100nF bypass capacitor to VREFGND |
| VREFGND (Pin 1) | Reference ground return | Dedicated low-noise ground for VREF; must be star-connected to minimize noise coupling |
| V+ (Pin 8), V− (Pin 6) | Power supply terminals | Support ±5V or 5V operation; V− connects to thermal pad for optimal junction cooling |
| VO4 / VO5 (Pins 12, 15) | Auxiliary op-amp outputs | Enable gain/offset adjustment of VLOGOUT to match ADC input ranges (e.g., 0–3.3V or ±2.5V) |
Key Features
| Feature | Design Value |
|---|---|
| On-chip temperature drift compensation | Reduces log-ratio error to ≤0.4% over −5°C to 75°C - critical for uncooled EDFA gain stabilization |
| Dual auxiliary operational amplifiers (A4/A5) | 15–60 MHz GBW, ±2 µV/°C offset drift - enables real-time scaling/offset correction of VLOGOUT before digitization |
| Wide input common-mode range | (V−)+1.5V to (V+)-1.5V - accommodates photodiode biasing schemes across varying supply rails |
| Low input bias current | ±5 pA - preserves accuracy when measuring sub-nanoamp photocurrents from high-impedance detectors |
| Fast transient response | 0.25 µs (10nA→1µA step) - supports dynamic optical power monitoring in burst-mode transmission systems |
Applications
| Optical Module Power Monitoring | Erbium-Doped Fiber Amplifier (EDFA) Control |
|---|---|
|
Use Scenario: Real-time monitoring of transmitter and receiver photodiode currents in SFP+/QSFP optical transceivers. IC Role / Device Role / Timing Role: Computes log(ITX/IRX) to derive optical link margin and detect fiber degradation. Use Value: 8-decade input range captures both low-power standby and high-power burst-mode currents without range switching. |
Use Scenario: Closed-loop gain stabilization in C-band EDFA modules using pump laser and output tap photodiodes. IC Role / Device Role / Timing Role: Measures log(Ipump/Ioutput) to maintain constant gain across temperature and aging. Use Value: On-chip 2.5V reference and temperature compensation ensure <0.4% error over −5°C to 75°C operating range. |
| Inter-Data-Center Optical Interconnect | Chemistry/Gas Analyzer Photodetection |
|
Use Scenario: High-speed optical power leveling in coherent DWDM links between geographically separated data centers. IC Role / Device Role / Timing Role: Delivers fast (≤0.8 µs) log-ratio updates for adaptive laser bias control during channel add/drop events. Use Value: 50 MHz GBW on VLOGOUT enables sub-microsecond response to rapid optical power transients. |
Use Scenario: Quantifying low-level absorption signals in NDIR gas sensors using infrared photodiodes. IC Role / Device Role / Timing Role: Converts 100pA–10µA photocurrents into linearized voltage outputs proportional to gas concentration. Use Value: ±5 pA input bias current prevents signal loss in high-impedance detector circuits with >1 GΩ feedback resistors. |
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 logarithmic detector (100MHz–4GHz), no dual-current inputs or auxiliary op-amps | Designed for RF power measurement, not DC/low-frequency photodiode current ratios | Select only for RF envelope detection; unsuitable for optical ratiometric sensing |
| LT1997-1IMS8#PBF | Programmable gain instrumentation amp with 10ppm/°C offset drift, no log function or internal reference | Requires external log circuitry and reference; lacks integrated temperature compensation | Choose when high-precision linear amplification is needed, but not for native log-ratio computation |
Compared with LOG114AIRGVRG4, ADL5513ACPZ-R7 offers RF bandwidth but no DC log-ratio capability, while LT1997-1IMS8#PBF provides precision linear gain but demands external components to replicate LOG114AIRGVRG4's monolithic log-ratio, reference, and temperature compensation functions.
Availability
LOG114AIRGVRG4 is available at Aetrix Electronics and suitable for optical module power monitoring, EDFA gain control, and inter-DC optical interconnect applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LOG114AIRGVRG4 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 conditioning and power management ICs.
The LOG114AIRGVRG4 belongs to TI's precision analog amplifier portfolio, engineered specifically for wide-dynamic-range current measurement in optical communications, medical instrumentation, and industrial sensing systems.
FAQ
What is the primary function of the LOG114AIRGVRG4?
The LOG114AIRGVRG4 is a precision logarithmic amplifier that computes the base-10 logarithm of the ratio of two input currents (I₁/I₂), delivering an output voltage scaled at 0.375 V/decade. It is optimized for photodiode current measurement in optical systems, with built-in 2.5V reference and temperature drift compensation. This function is explicitly defined in TI's SBOS301C datasheet Section 6.1 and implemented via matched A1/A2 log amps and A3 difference amplifier.
Can the LOG114AIRGVRG4 operate from a single 5V supply?
Yes, the LOG114AIRGVRG4 supports both ±5V and single 5V supply configurations, as confirmed in Section 5.3 Recommended Operating Conditions and Section 5.6 Electrical Characteristics (5V) of the SBOS301C datasheet. In 5V mode, V+ = 5V and V− = GND, with VLOGOUT equation adjusted to VO = 0.375×log(I₁/I₂)+VCM. Input common-mode range remains (V−)+1.5V to (V+)−1.5V, enabling compatibility with standard 5V-system photodiode biasing.
What is the role of the COM pin on the LOG114AIRGVRG4?
The COM pin on the LOG114AIRGVRG4 sets the common-mode voltage for the internal difference amplifier (A3), directly adding a DC offset to the VLOGOUT signal per Equation 2 in Section 7.1.1. When a voltage (e.g., 2.5V) is applied to COM, VLOGOUT becomes 0.375×log(I₁/I₂)+VCOM - enabling output centering for ADCs with asymmetric input ranges. This functionality is documented in Figure 4-1 pin description and Section 6.3.2 of SBOS301C.
Does the LOG114AIRGVRG4 include an internal voltage reference?
Yes, the LOG114AIRGVRG4 integrates a 2.5V bandgap voltage reference (VREF pin 16), specified with ±1% initial error and ±25 ppm/°C drift over −5°C to 75°C (Section 5.5/5.6). This reference is used internally for temperature compensation and externally to generate precise I₂ reference current via an external resistor. VREFGND (pin 1) is a dedicated low-noise ground return, required for reference stability.
What are the absolute maximum input current limits for the LOG114AIRGVRG4?
The LOG114AIRGVRG4 has an absolute maximum input current rating of ±10 mA per input (I₁ or I₂), as stated in Section 5.1 Absolute Maximum Ratings. However, for specified accuracy, input current must be limited to 100 pA–3.5 mA (Section 7.1.2). Exceeding 3.5 mA increases nonlinearity, and currents above 10 mA risk damaging the input transistors due to excessive power dissipation - a hard limit enforced by TI's production design.
LOG114AIRGVRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-VQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Amplifier Type:
- Logarithmic
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 5V/µs
- Gain Bandwidth Product:
- 15 MHz
- -3db Bandwidth:
- 5 MHz
- Current - Input Bias:
- 5 pA
- Voltage - Input Offset:
- 100 µV
- Current - Supply:
- 10mA
- Current - Output / Channel:
- -
- Voltage - Supply Span (Min):
- 4.8 V
- Voltage - Supply Span (Max):
- 11 V
- Operating Temperature:
- -5°C ~ 75°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-VQFN (4x4)
LOG114AIRGVRG4 FAQ
1.How can I place an order for LOG114AIRGVRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for LOG114AIRGVRG4 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 LOG114AIRGVRG4 reliable?
The price and inventory of LOG114AIRGVRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LOG114AIRGVRG4 is usually 5 days.
3.What payment methods are accepted for LOG114AIRGVRG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LOG114AIRGVRG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LOG114AIRGVRG4?
LOG114AIRGVRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LOG114AIRGVRG4 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 LOG114AIRGVRG4?
For technical support, including LOG114AIRGVRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LOG114AIRGVRG4 requirements.
6.How does Aetrix verify that LOG114AIRGVRG4 is sourced from the original manufacturer or authorized distributors?
All LOG114AIRGVRG4 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 LOG114AIRGVRG4 meets industry standards.
7.What is the process for return or replacement of LOG114AIRGVRG4?
All LOG114AIRGVRG4 units undergo pre-shipment inspection (PSI). If there is an issue with LOG114AIRGVRG4, 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 LOG114AIRGVRG4 part is unused and in its original packaging.
Return procedure for LOG114AIRGVRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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