Texas Instruments LM4128BMF-1.8

Overview

LM4128BMF-1.8 from National Semiconductor is a precision micropower series voltage reference in SOT-23-5 package, delivering 1.8 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 and supports up to 20 mA load current - ideal for battery-powered instrumentation and portable data acquisition systems.

For engineers reviewing the LM4128BMF-1.8 datasheet, LM4128BMF-1.8 pinout, LM4128BMF-1.8 application, or LM4128BMF-1.8 equivalent, key selection criteria include dropout voltage (400 mV at 10 mA), line regulation (30 ppm/V), load regulation (25–120 ppm/mA), and stability with capacitive loads up to 10 µF without external compensation.

Technical Context

The LM4128BMF-1.8 employs a band-gap-derived series reference architecture with internal enable control logic and thermal-hysteresis-compensated core. Its design eliminates need for output stabilization capacitors while maintaining stability under 10 µF capacitive loading and tolerating input ripple via low-noise internal regulation.

It operates across −40°C to +125°C junction temperature, accepts input voltages from (VREF + 400 mV) to 5.5 V, and delivers precise 1.8 V output with 170 µV_PP (0.1–10 Hz) noise - optimized for high-resolution ADC biasing and low-power sensor signal conditioning where supply headroom and long-term drift matter.

Key Specifications

Pinout & Package

SOT-23-5 package (NS MF05A), surface-mount, 1.6 mm × 2.9 mm footprint with 0.95 mm height - optimized for space-constrained PCB layouts in handheld test gear and medical wearables.

Key Features

Applications

Equivalent & Alternatives

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

Compared with REF3018AIDBVR and MAX6029AEUR+T, the LM4128BMF-1.8 uniquely combines EN-controlled shutdown, guaranteed 10 µF capacitive load stability, and industry-standard SOT-23-5 footprint - making it optimal for battery-cycled, space-constrained, and high-reliability analog signal chains.

Availability

LM4128BMF-1.8 is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered test equipment, and industrial data acquisition systems requiring stable component supply across extended production lifecycles.

Supply support for LM4128BMF-1.8 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 medical designs.

The LM4128 family was designed specifically for micropower, high-accuracy voltage referencing in space- and energy-constrained applications - emphasizing low dropout, capacitor-free stability, and wide temperature operation.

FAQ

What is the minimum input voltage required for stable operation of the LM4128BMF-1.8?

The LM4128BMF-1.8 requires VIN ≥ VREF + 400 mV, i.e., ≥2.2 V, to maintain regulation at 10 mA load. Below this threshold, output voltage drops nonlinearly; operation is guaranteed only within 2.2 V to 5.5 V input range per Absolute Maximum Ratings and Electrical Characteristics tables.

Does the LM4128BMF-1.8 require an input capacitor, and if so, what value is recommended?

Yes - a minimum 0.1 µF ceramic (X5R/X7R) input capacitor (C_IN) is mandatory for stable operation. When an output capacitor is used, C_IN must be ≥ C_OUT; for best noise suppression and startup behavior, 4.7 µF to 22 µF is recommended, placed close to the VIN and GND pins of the LM4128BMF-1.8.

Can the LM4128BMF-1.8 drive a 10 µF capacitive load without oscillation?

Yes - the LM4128BMF-1.8 is explicitly characterized and guaranteed stable with capacitive loads up to 10 µF, including low-ESR ceramic types. This eliminates need for external isolation resistors or damping networks typically required by older reference architectures.

What is the typical turn-on time of the LM4128BMF-1.8 when enabled from shutdown?

The LM4128BMF-1.8 has a typical turn-on time of 33.2 µs into a 1 µF load and 78.8 µs into a 10 µF load. Under brown-out conditions or at −40°C, turn-on may extend up to 10 ms - a design consideration for fast-wakeup sensor nodes using the EN pin.

How does the enable pin (EN) interface electrically with microcontroller GPIOs?

The EN pin of the LM4128BMF-1.8 is compatible with standard 1.8 V, 3.3 V, or 5 V GPIOs: VIH ≥ 65% of VIN and VIL ≤ 35% of VIN. With internal 2 µA pull-up, it can be driven directly by open-drain or push-pull outputs; no external pull-up is required unless VIN is unpowered during enable assertion.