Texas Instruments LM4128BMF-3.3

Overview

LM4128BMF-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 from −40°C to +125°C - ideal for battery-powered instrumentation and portable data acquisition systems.

For engineers reviewing the LM4128BMF-3.3 datasheet, LM4128BMF-3.3 pinout, LM4128BMF-3.3 application, or LM4128BMF-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), 310 µV_PP (0.1–10 Hz) output noise, and compatibility with capacitive loads up to 10 µF without external stabilization.

Technical Context

The LM4128BMF-3.3 uses a band-gap–derived reference core with internal enable logic and low-dropout series architecture. Its design eliminates need for external stabilization capacitors while maintaining stability with ceramic output capacitance up to 10 µF and input capacitance ≥ C_OUT.

It operates across VIN = VREF + 400 mV to 5.5 V, delivers 3.3 V with guaranteed performance over −40°C to +125°C junction temperature, and integrates indefinite short-circuit protection (75 mA limit) and thermal hysteresis of ≤75 ppm.

Key Specifications

Pinout & Package

SOT-23-5 package (NS package number MF05A), surface-mount, 1.6 mm × 2.9 mm footprint, rated for −40°C to +125°C junction temperature.

Key Features

Applications

Equivalent & Alternatives

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

Compared with REF3033AIDBZR and MAX6029BESA33+, the LM4128BMF-3.3 uniquely combines B-grade precision, integrated enable functionality, and proven 10 µF capacitive-load stability - making it optimal for space-constrained, battery-aware designs requiring both accuracy and dynamic power control.

Availability

LM4128BMF-3.3 is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered sensors, and industrial process transmitters requiring stable component supply with long-term parametric consistency and automotive-grade traceability options.

Supply support for LM4128BMF-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 pioneer, acquired by Texas Instruments in 2011; its precision reference portfolio remains widely deployed in industrial and automotive systems.

The LM4128 family was designed specifically for micropower, space-constrained applications demanding high accuracy, low dropout, and robust capacitive-load stability - targeting portable test equipment, sensor nodes, and automotive subsystems.

FAQ

What is the minimum input voltage required for LM4128BMF-3.3 to regulate properly?

The LM4128BMF-3.3 requires VIN ≥ VREF + 400 mV, i.e., ≥3.7 V at 10 mA load. At lighter loads, dropout decreases - e.g., 200 mV at 10 mA for 3.0 V versions, but LM4128BMF-3.3 specifies 400 mV max across grades. Below this threshold, output drops nonlinearly and regulation is not guaranteed. Always verify margin using worst-case 400 mV dropout in design.

Does LM4128BMF-3.3 require an input capacitor, and what value is recommended?

Yes - a ceramic input capacitor (X5R/X7R) is mandatory for stable operation. Minimum C_IN = 0.1 µF if no output capacitor is used; otherwise C_IN ≥ C_OUT. For optimal noise suppression and startup behavior, 4.7 µF to 22 µF is recommended. Mount C_IN close to pins 4 (VIN) and 2 (GND) to minimize parasitic inductance.

Can LM4128BMF-3.3 drive a 10 µF capacitive load without oscillation?

Yes - the LM4128BMF-3.3 is explicitly characterized and guaranteed stable with capacitive loads up to 10 µF, including low-ESR ceramic types. This eliminates need for series resistance or isolation buffers in most applications, simplifying layout and reducing component count compared to older references requiring external compensation.

What is the function of Pin 1 (N/C) on LM4128BMF-3.3, and how should it be handled?

Pin 1 is a no-connect terminal and must remain unconnected and electrically floating - not tied to GND, VIN, or any other net. Internal die connection is absent; routing or soldering to this pin may induce mechanical stress or leakage paths that degrade long-term stability or tempco performance per datasheet mechanical layout guidance.

How does the enable pin (Pin 3) of LM4128BMF-3.3 interface with standard logic levels?

The enable pin accepts CMOS-compatible thresholds: VIH ≥ 65% of VIN (e.g., ≥2.44 V when VIN = 3.7 V) to activate, and VIL ≤ 35% of VIN (e.g., ≤1.3 V) to enter 3 µA shutdown. It features an internal ~2 µA pull-up, so leaving EN open defaults to active mode - but for deterministic control, drive actively high/low from MCU GPIO or dedicated enable sequencer.