My Inquiry
My Account
Texas Instruments 4127KG
- Part No.:
- 4127KG
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 24-CDIP (0.600", 15.24mm)
- Datasheet:
-
4127KG.pdf
- Description:
- IC LOGARITHMIC 2 CIRCUIT 24CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,831
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
4127KG from Texas Instruments (formerly Burr-Brown) is a hybrid logarithmic amplifier IC that accepts bipolar input currents (±1nA to ±1mA) and voltages (±1mV to ±10V), delivers ±10V log output with 0.5% log conformity, and integrates a current inverter, precision reference, and uncommitted op amp - used for phototube buffering and transducer linearization in analytical instrumentation.
For engineers reviewing the 4127KG datasheet, 4127KG pinout, 4127KG application, or 4127KG equivalent, this page provides verified pin functions, log/antilog/log-ratio configuration details, temperature-stable scaling behavior, and real-world selection guidance for signal compression systems requiring wide-dynamic-range analog computation.
Technical Context
The 4127KG implements logarithmic conversion using matched monolithic quad transistors and temperature-compensated gain elements (520Ω thermistor RT), enabling accurate log response across six decades of current (1nA–1mA) and four decades of voltage (1mV–10V). Its FET-input op amps (A1, A3) provide low input bias current (40nA) and low noise (1pA rms, 10Hz–10kHz).
Pin-programmable operation supports logarithmic (EO = –A log|IS|/IR), log-ratio (two-input current mode), and antilog modes via external resistors R1 (sets IR) and R2 (sets scale factor A). The integrated current inverter enables true bipolar input handling without external polarity-reversal circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Log Conformity Accuracy | 0.5% max over full-scale output (±10V), enabling high-fidelity compression in medical sensor front-ends. |
| Input Current Range | ±1nA to ±1mA (6-decade dynamic range), supporting ultra-low-level photodiode signals up to industrial current-loop levels. |
| Input Voltage Range | ±1mV to ±10V (4-decade range), compatible with millivolt-output thermocouples and 10V industrial sensors. |
| Output Voltage Swing | ±10V into 10Ω load, directly interfacing with ADCs, data acquisition systems, and analog recorders. |
| Small-Signal Bandwidth | 90kHz at 100µA input; drops to 80Hz at 10nA - design must account for signal-level-dependent frequency response. |
| Supply Requirements | ±15VDC (±14V to ±16V range), with quiescent current ≤ ±20mA - requires stable dual-rail lab or instrumentation power. |
| Operating Temperature | –10°C to +70°C ambient, with specified performance from 0°C to +60°C - suitable for benchtop analyzers, not extended-temperature industrial enclosures. |
Pinout & Package
Packaged in a 24-pin ceramic dual-in-line package (CDIP, drawing JNA), the 4127KG uses a double-wide footprint with 0.300" width and 0.600" length, rated for hermetic sealing and high-reliability analog applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 3, 6, 8–10, 12, 13, 15–17, 20 | No Connect (NC) | Internally unconnected; must remain floating - no routing or grounding allowed. |
| 2 | IREF Input | Accepts external reference current (1µA–1mA) to set log scaling denominator IR. |
| 4, 5 | +I Input | Internally connected positive-current input node; accepts +1nA to +1mA for log computation. |
| 7 | Current Inverter Input | Accepts negative input current (–1nA to –1mA); inverted internally to positive for log processing. |
| 11 | Log Output | Primary output delivering EO = –A log|IS|/IR; buffered, ±10V capable, 10Ω source impedance. |
| 14 | Gain Adjust | Connects external resistor R2 to set scale factor A (1V–10V); determines output volts per decade. |
| 18, 19 | Op Amp ±Input | Uncommitted op amp inputs - configurable as buffer, inverter, filter, or gain stage for post-log conditioning. |
| 21 | Op Amp Output | Output of internal op amp; usable for offset correction, filtering, or driving low-impedance loads. |
| 22, 23 | ±15VDC Supply | Separate pins for positive and negative supply rails; decoupling required within 1 inch of package. |
| 24 | Common | Analog ground reference for all internal circuitry; must connect to clean system AGND plane. |
Key Features
| Feature | Design Value |
|---|---|
| Bipolar Input Acceptance | Handles both positive and negative current/voltage inputs without external polarity-switching circuitry - reduces component count in multi-sensor systems. |
| Configurable Log Function | Pin-selectable as logarithmic, log-ratio, or antilog amplifier via resistor networks - enables single-part reuse across compression, ratio-metric, and exponential signal paths. |
| Integrated Current Inverter | On-chip inverter converts negative input current to positive magnitude before log computation - eliminates need for discrete inverting op amp stage. |
| Uncommitted Op Amp | Dedicated FET-input op amp (5mV offset, 40nA bias) for post-processing - allows on-package offset trimming, filtering, or gain adjustment without external ICs. |
| Temperature-Compensated Scaling | 520Ω thermistor (RT) tracks gain drift vs. temperature - maintains scale factor stability (±0.0005A/°C) across operating range. |
Applications
| Phototube Signal Conditioning | Transducer Linearization |
|---|---|
Use Scenario: Amplifying low-level, wide-dynamic-range current from vacuum phototubes in spectrophotometers and particle detectors. IC Role / Device Role / Timing Role: Logarithmic amplifier converting photocurrent (1nA–1mA) into linear-in-decade voltage for digitization and display. Use Value: Enables 6-decade signal capture in single-channel readout without range-switching, reducing system complexity and measurement latency. | Use Scenario: Linearizing nonlinear output of RTDs, thermistors, or strain gauges in process control transmitters. IC Role / Device Role / Timing Role: Voltage-mode log amplifier accepting ±1mV–±10V sensor outputs and generating compressed, linearized analog representation. Use Value: Compensates for inherent exponential sensor nonlinearity while preserving resolution at low signal levels - improves accuracy over full temperature span. |
| Medical Instrumentation Front-End | Analytical Instrument Signal Compression |
Use Scenario: Processing ion-current signals from mass spectrometers or electrophoresis detectors with >100dB dynamic range. IC Role / Device Role / Timing Role: High-accuracy log amplifier (0.5% conformity) providing analog compression prior to 12-bit ADC sampling. Use Value: Maintains sub-percent linearity across decades of input, enabling quantitative peak-area analysis without digital correction algorithms. | Use Scenario: Compressing wide-range analog outputs from gas chromatography detectors or pH meters for analog recording or telemetry. IC Role / Device Role / Timing Role: Configured as log-ratio amplifier comparing two current inputs (e.g., sample vs. reference beam) to reject common-mode drift. Use Value: Delivers ratiometric stability independent of supply or temperature drift - critical for long-duration lab instrument calibration integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar logarithmic amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD8304ACPZ-R7 | Monolithic 80dB log amp (100pA–100µA), 2.7–5.5V single supply, no bipolar input support. | Limited to unipolar current inputs; lacks integrated op amp and current inverter - requires external components for bipolar or post-log functions. | Select when low-voltage, space-constrained designs prioritize integration density over bipolar flexibility. |
| LOG114EUE | Monolithic 7-decade log amp (1pA–1mA), ±5V supply, includes reference but no current inverter or uncommitted op amp. | Higher sensitivity (1pA min), but no native negative-input capability - needs external inverter for bipolar operation. | Select when ultra-low-current detection dominates requirements and external inversion is acceptable. |
Compared with AD8304ACPZ-R7 and LOG114EUE, the 4127KG uniquely combines true bipolar input handling, on-chip current inversion, and a fully functional op amp in one hybrid package - making it irreplaceable for legacy instrumentation requiring ±1nA–±1mA log compression without added active components.
Availability
4127KG is available at Aetrix Electronics and suitable for analytical instrumentation, medical equipment, and process control systems requiring stable component supply for long-lifecycle, low-volume production.
Supply support for 4127KG 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 (TI) acquired Burr-Brown in 2000 and maintains legacy analog product support, including precision amplifiers and signal-conditioning ICs.
The 4127KG belongs to TI's heritage high-accuracy analog computing IC family, designed specifically for laboratory-grade instrumentation requiring wide-dynamic-range logarithmic signal processing without digital intervention.
FAQ
What is the maximum input current the 4127KG can handle without damage?
The 4127KG has absolute maximum input ratings of ±10mA or ±supply volts, whichever is less. However, its specified accurate logarithmic operation is limited to ±1nA to ±1mA. Exceeding ±1mA may cause deviation from log conformity or thermal stress, though the device remains undamaged up to ±10mA per absolute maximum ratings.
Does the 4127KG support true log-ratio functionality, and how is it configured?
Yes, the 4127KG supports true log-ratio operation using two current inputs (e.g., pins 4 and 7) to compute EO = –A log|I1|/|I2|. Configuration requires external resistors to set reference current (R1) and scale factor (R2), with I2 ≥ 1µA and |I1| ≥ 1nA. The internal current inverter enables ratio computation with mixed-polarity inputs.
Can the 4127KG be used for antilog operations, and what external components are required?
Yes, the 4127KG performs antilog by feeding its log output (pin 11) through resistor RO back to the current input (pin 4), while applying the input signal to pin 19. Required components include RO (e.g., 1MΩ for unity scale) and R1/R2 to set IR and A. A 0.01µF capacitor between pins 18–19 suppresses oscillation if needed.
What is the role of the uncommitted op amp in the 4127KG, and what are its key electrical limits?
The uncommitted op amp (pins 18, 19, 21) provides post-log signal conditioning. It features 5mV input offset voltage, 40nA input bias current, 1MΩ input impedance, 85dB large-signal gain, and ±5mA output drive. It can buffer the log output, invert polarity, add gain, or implement active filtering without external amplifiers.
Is the 4127KG still in active production, and what does NRND status mean for new designs?
The 4127KG carries an NRND (Not Recommended for New Designs) status per TI's packaging addendum. It remains available for existing programs but TI advises against new designs due to obsolescence trajectory. Aetrix Electronics supports continued supply with traceable sourcing and lifecycle coordination for legacy instrumentation maintenance.
4127KG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 24-CDIP (0.600", 15.24mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Amplifier Type:
- Logarithmic
- Number of Circuits:
- 2
- Output Type:
- -
- Slew Rate:
- -
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 90 kHz
- Current - Input Bias:
- 40 nA
- Voltage - Input Offset:
- 5 mV
- Current - Supply:
- 20mA
- Current - Output / Channel:
- 5 mA
- Voltage - Supply Span (Min):
- 28 V
- Voltage - Supply Span (Max):
- 32 V
- Operating Temperature:
- 0°C ~ 60°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 24-CDIP
4127KG FAQ
1.How can I place an order for 4127KG through Aetrix?
Please submit a Request for Quotation (RFQ) for 4127KG 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 4127KG reliable?
The price and inventory of 4127KG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 4127KG is usually 5 days.
3.What payment methods are accepted for 4127KG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 4127KG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 4127KG?
4127KG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 4127KG 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 4127KG?
For technical support, including 4127KG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 4127KG requirements.
6.How does Aetrix verify that 4127KG is sourced from the original manufacturer or authorized distributors?
All 4127KG 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 4127KG meets industry standards.
7.What is the process for return or replacement of 4127KG?
All 4127KG units undergo pre-shipment inspection (PSI). If there is an issue with 4127KG, 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 4127KG part is unused and in its original packaging.
Return procedure for 4127KG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
4127KG Tags
-
LM358DT
STMicroelectronics
-
LM358DR
Texas Instruments
-
LM2904DR
Texas Instruments
-
LM358ADR
Texas Instruments
-
LM2904DGKR
Texas Instruments
-
LM324DR
Texas Instruments
-
MCP6006T-E/OT
Microchip Technology
-
MCP6006UT-E/OT
Microchip Technology
-
LM324PWR
Texas Instruments
-
LM2902PWR
Texas Instruments
-
LM2902DR
Texas Instruments
-
LM358P
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
