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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Reference

Texas Instruments LM4128BMFX-3.3

Name: LM4128BMFX-3.3
Brand: Texas Instruments
SKU: LM4128BMFX-3.3
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LM4128BMFX-3.3

Manufacturer:: Texas Instruments

Category:: Voltage Reference

Package:: SC-74A, SOT-753

Datasheet:: LM4128BMFX-3.3.pdf

Description:: IC VREF SERIES 0.2% SOT23-5

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Product details

Overview

LM4128BMFX-3.3 from National Semiconductor is a precision micropower series voltage reference in SOT-23-5 package, delivering 3.3 V output with ±0.2% initial accuracy, 75 ppm/°C temperature coefficient, and 60 µA quiescent current. It features an enable pin for 3 µA shutdown mode, supports up to 20 mA load, and operates across −40°C to +125°C - ideal for battery-powered instrumentation and portable data acquisition systems.

For engineers reviewing the LM4128BMFX-3.3 datasheet, LM4128BMFX-3.3 pinout, LM4128BMFX-3.3 application, or LM4128BMFX-3.3 equivalent, key selection considerations include dropout voltage (≤400 mV at 10 mA), line regulation (85 ppm/V), load regulation (25–120 ppm/mA), noise performance (310 µV_PP, 0.1–10 Hz), and AEC-Q100-comparable B-grade stability in space-constrained designs.

Technical Context

The LM4128BMFX-3.3 employs a band-gap-derived series reference architecture with internal enable control logic, eliminating need for external stabilization capacitors while maintaining stability with capacitive loads up to 10 µF. Its low dropout (VIN ≥ VREF + 400 mV) and micropower operation (60 µA active, 3 µA shutdown) support direct integration into low-voltage, high-precision analog signal chains.

Designed for robustness in industrial and automotive-adjacent applications, it guarantees ±0.2% output accuracy over temperature (−40°C to +125°C) and exhibits 75 ppm/°C tempco - matching A-grade performance in thermal drift while offering cost-optimized B-grade specification. The enable pin accepts logic-level inputs referenced to VIN, with defined VIH/VIL thresholds (65%/35% of VIN).

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	3.3 V nominal, ±0.2% initial accuracy at 25°C - ensures ≤±6.6 mV absolute error before calibration.
Temperature Coefficient	75 ppm/°C max - contributes ≤±24.8 mV drift over −40°C to +125°C operating range.
Quiescent Current	60 µA typical - enables multi-year battery life in always-on sensor nodes drawing <100 µA system current.
Shutdown Current	3 µA max - reduces power by >95% during idle periods without external circuitry.
Dropout Voltage	400 mV max at 10 mA load - allows operation from 3.7 V Li-ion cells down to end-of-discharge (~3.3 V + 0.4 V).
Output Noise	310 µV_PP (0.1–10 Hz) - supports 16-bit ADCs (e.g., ADS8860) without additional filtering.
Line Regulation	85 ppm/V - introduces ≤±0.28 mV change per 1 V input variation within VREF + 400 mV to 5.5 V range.
Load Regulation	25–120 ppm/mA - maintains stability across 0–20 mA load, critical for variable-current DAC buffers.

Pinout & Package

SOT-23-5 package (NS package number MF05A), 1.6 mm × 2.9 mm footprint, 1.1 mm height, lead-free and RoHS compliant.

Pin/Terminal	Circuit Role	Design Meaning
1	N/C	No-connect pin; must remain unconnected and floating - not internally bonded.
2	GND	Analog ground reference; requires low-impedance connection to system AGND plane.
3	EN	Active-high enable input; pulls up internally (~2 µA); drives high to activate reference output.
4	VIN	Input supply rail; must exceed VREF + 400 mV (≥3.7 V for 3.3 V output) and stay ≤5.5 V.
5	VREF	Precision 3.3 V output; capable of sourcing up to 20 mA with <120 ppm/mA load regulation.

Key Features

Feature	Design Value
Enable-controlled shutdown	Reduces supply current to ≤7 µA, enabling firmware-governed power cycling without external MOSFETs.
Capacitor-free stability	Operates stably without output capacitor and supports up to 10 µF ceramic loads - simplifies layout in dense PCBs.
Low ESR ceramic compatibility	Validated with X5R/X7R MLCCs; eliminates need for tantalum or electrolytic bypassing.
Indefinite short-circuit protection	Limits output current to 75 mA during fault conditions - prevents thermal runaway and enables safe recovery.
Wide junction temperature range	Specified from −40°C to +125°C - suitable for under-hood automotive modules and industrial enclosures.

Applications

Portable Data Acquisition	Automotive Sensor Interface
Use Scenario: Handheld multimeter sampling 16-bit SAR ADC with 3.3 V reference rail. IC Role / Device Role / Timing Role: Precision voltage reference establishing full-scale ADC input range. Use Value: ±0.2% initial accuracy and 75 ppm/°C tempco ensure <0.5 LSB total error across 0–50°C ambient range.	Use Scenario: Tire pressure monitoring system (TPMS) ECU measuring piezoresistive bridge output. IC Role / Device Role / Timing Role: Stable excitation reference for ratiometric bridge sensing. Use Value: 3 µA shutdown current extends coin-cell lifetime beyond 5 years; −40°C to +125°C rating covers full vehicle operating envelope.
Industrial Process Controller	Battery-Powered Medical Monitor
Use Scenario: 4–20 mA loop transmitter using DAC with external reference. IC Role / Device Role / Timing Role: Low-drift reference for current-loop DAC output calibration. Use Value: 85 ppm/V line regulation minimizes output error when powered from unregulated 24 V supply with ripple.	Use Scenario: Portable ECG front-end with 3.3 V rail powering analog signal chain and microcontroller. IC Role / Device Role / Timing Role: Shared reference for ADC, DAC, and comparator circuits. Use Value: 310 µV_PP (0.1–10 Hz) noise meets IEC 60601-2-27 low-frequency ECG noise requirements without added filtering.

Portable Data Acquisition

Automotive Sensor Interface

Use Scenario: Handheld multimeter sampling 16-bit SAR ADC with 3.3 V reference rail.

IC Role / Device Role / Timing Role: Precision voltage reference establishing full-scale ADC input range.

Use Value: ±0.2% initial accuracy and 75 ppm/°C tempco ensure <0.5 LSB total error across 0–50°C ambient range.

Use Scenario: Tire pressure monitoring system (TPMS) ECU measuring piezoresistive bridge output.

IC Role / Device Role / Timing Role: Stable excitation reference for ratiometric bridge sensing.

Use Value: 3 µA shutdown current extends coin-cell lifetime beyond 5 years; −40°C to +125°C rating covers full vehicle operating envelope.

Industrial Process Controller

Battery-Powered Medical Monitor

Use Scenario: 4–20 mA loop transmitter using DAC with external reference.

IC Role / Device Role / Timing Role: Low-drift reference for current-loop DAC output calibration.

Use Value: 85 ppm/V line regulation minimizes output error when powered from unregulated 24 V supply with ripple.

Use Scenario: Portable ECG front-end with 3.3 V rail powering analog signal chain and microcontroller.

IC Role / Device Role / Timing Role: Shared reference for ADC, DAC, and comparator circuits.

Use Value: 310 µV_PP (0.1–10 Hz) noise meets IEC 60601-2-27 low-frequency ECG noise requirements without added filtering.

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision voltage reference applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
REF3033AIDBZR	0.1% initial accuracy, 50 ppm/°C tempco, 50 µA IQ, SOT-23-3 (no EN pin)	Higher accuracy and lower drift, but lacks enable control and uses 3-pin package - requires board redesign.	Select for ultra-low-drift systems where shutdown is managed externally or unnecessary.
MAX6029BESA33+T	0.2% initial accuracy, 75 ppm/°C tempco, 35 µA IQ, SC70-5 (EN pin present), 10 µF load stable	Lower quiescent current and smaller SC70 footprint; same grade spec but different enable threshold (VIH = 1.4 V min).	Prefer when minimizing board area and active current is critical; verify EN logic compatibility with host MCU.

Compared with REF3033AIDBZR and MAX6029BESA33+T, the LM4128BMFX-3.3 offers identical B-grade accuracy and tempco with proven 10 µF capacitive-load stability and integrated enable functionality - making it optimal for drop-in upgrades in existing SOT-23-5 layouts requiring shutdown capability.

Availability

LM4128BMFX-3.3 is available at Aetrix Electronics and suitable for portable instrumentation, automotive sensor interfaces, and industrial process controllers requiring stable component supply with guaranteed long-term availability.

Supply support for LM4128BMFX-3.3 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

National Semiconductor was a U.S.-based analog semiconductor company acquired by Texas Instruments in 2011; its precision reference portfolio remains widely deployed in industrial and automotive systems.

The LM4128 family was designed for space-constrained, battery-sensitive applications demanding high DC accuracy, low thermal drift, and simple integration - targeting portable test equipment, sensor signal conditioning, and embedded data converters.

FAQ

What is the maximum input voltage for LM4128BMFX-3.3?

The LM4128BMFX-3.3 supports a maximum input voltage of 5.5 V. Operation above this level risks permanent damage. The minimum valid input is VREF + 400 mV (≥3.7 V), ensuring proper regulation under 10 mA load. Exceeding the 5.5 V absolute maximum rating voids reliability guarantees and may trigger latch-up.

Does LM4128BMFX-3.3 require an input capacitor?

Yes - the LM4128BMFX-3.3 requires a minimum 0.1 µF ceramic input capacitor (X5R/X7R) for stable operation. When an output capacitor is used, CIN must be ≥ COUT. Larger values (4.7–22 µF) reduce startup overshoot and power-supply noise coupling, directly improving reference accuracy in noisy environments.

Can LM4128BMFX-3.3 drive a 10 µF capacitive load?

Yes - the LM4128BMFX-3.3 is explicitly characterized for stability with capacitive loads up to 10 µF, including low-ESR ceramic types. This eliminates need for isolation resistors or damping networks, simplifying design in applications like DAC output buffering or ADC reference decoupling where large local capacitance is required.

What is the enable pin behavior of LM4128BMFX-3.3?

The EN pin on LM4128BMFX-3.3 is active-high with internal ~2 µA pull-up. It activates the reference when driven ≥65% of VIN and disables it when ≤35% of VIN. Leaving EN floating enables the device by default. Driving EN low reduces supply current to ≤7 µA, entering low-power shutdown mode without external components.

Is LM4128BMFX-3.3 qualified for automotive use?

The LM4128BMFX-3.3 is not AEC-Q100 qualified; only LM4128BQ1MFX-3.3 (Q-grade) carries that certification. However, LM4128BMFX-3.3 shares identical electrical specs, −40°C to +125°C operating range, and robust construction - making it suitable for non-safety-critical automotive subsystems where formal qualification is not mandated.

LM4128BMFX-3.3 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Package/Case:: SC-74A, SOT-753

Series:: -

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Reference Type:: Series

Output Type:: Fixed

Voltage - Output (Min/Fixed):: 3.3V

Voltage - Output (Max):: -

Current - Output:: 20 mA

Tolerance:: ±0.2%

Temperature Coefficient:: 75ppm/°C

Noise - 0.1Hz to 10Hz:: 310µVp-p

Noise - 10Hz to 10kHz:: -

Voltage - Input:: 3.7V ~ 5.5V

Current - Supply:: 100µA

Current - Cathode:: -

Operating Temperature:: -40°C ~ 125°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-5

LM4128BMFX-3.3 FAQ

1.How can I place an order for LM4128BMFX-3.3 through Aetrix?

Please submit a Request for Quotation (RFQ) for LM4128BMFX-3.3 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 LM4128BMFX-3.3 reliable?

The price and inventory of LM4128BMFX-3.3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM4128BMFX-3.3 is usually 5 days.

3.What payment methods are accepted for LM4128BMFX-3.3?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM4128BMFX-3.3 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LM4128BMFX-3.3?

LM4128BMFX-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LM4128BMFX-3.3 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 LM4128BMFX-3.3?

For technical support, including LM4128BMFX-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM4128BMFX-3.3 requirements.

6.How does Aetrix verify that LM4128BMFX-3.3 is sourced from the original manufacturer or authorized distributors?

All LM4128BMFX-3.3 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 LM4128BMFX-3.3 meets industry standards.

7.What is the process for return or replacement of LM4128BMFX-3.3?

All LM4128BMFX-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM4128BMFX-3.3, 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 LM4128BMFX-3.3 part is unused and in its original packaging.

Return procedure for LM4128BMFX-3.3:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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