Texas Instruments LM4140ACMX-2.5/NOPB

Overview

LM4140ACMX-2.5/NOPB from Texas Instruments is a high-precision, low-noise, low-dropout series voltage reference delivering 2.5 V output with ±0.1% initial accuracy, 3 ppm/°C temperature coefficient (A grade), and 20 mV typical dropout at 1 mA. It features an enable pin for power management and supports precision ADC/DAC biasing in portable instrumentation and battery-powered data acquisition systems.

For engineers reviewing the LM4140ACMX-2.5/NOPB datasheet, LM4140ACMX-2.5/NOPB pinout, LM4140ACMX-2.5/NOPB application, or LM4140ACMX-2.5/NOPB equivalent, key selection considerations include its ultra-low 2.2 µV_PP (0.1–10 Hz) noise, 230 µA typical supply current, 1 µA shutdown current, and SOIC-8 package compatibility with standard PCB layouts for high-stability analog signal chains.

Technical Context

The LM4140ACMX-2.5/NOPB uses EEPROM-trimmed CMOS DACs for curvature-corrected temperature compensation and output voltage trimming-enabling 3 ppm/°C drift performance without laser trimming. Its P-channel pass transistor architecture allows operation down to VIN = VREF + 20 mV (typical), supporting low-voltage systems as low as 1.8 V input.

It integrates internal charge-discharge circuitry on the enable pin to rapidly disable the output and actively sink the 1 µF output capacitor during shutdown, achieving full turn-off in <200 µs. The device operates over 0°C to 70°C and requires a minimum 1 µF output capacitor for loop stability and transient response.

Key Specifications

Pinout & Package

LM4140ACMX-2.5/NOPB is housed in an 8-pin SOIC package (4.90 mm × 3.91 mm body size) with exposed pad not present. Pin functions are validated per TI SNVS053F Rev F datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with REF5025IDR and ADR4525BRZ, LM4140ACMX-2.5/NOPB uniquely balances ultra-low dropout (20 mV), integrated enable, and A-grade stability at lower cost-making it optimal for space-constrained, battery-operated systems needing rapid power cycling and 1.8 V compatibility.

Availability

LM4140ACMX-2.5/NOPB is available at Aetrix Electronics and suitable for portable instrumentation, precision data acquisition, battery-powered sensors, medical vital signs monitoring, and industrial process control requiring stable component supply across design-in, prototyping, and volume production phases.

Supply support for LM4140ACMX-2.5/NOPB 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 company headquartered in Dallas, Texas, specializing in analog and embedded processing technologies with broad industrial, automotive, and consumer applications.

The LM4140 product line was designed specifically for high-accuracy, low-noise, low-dropout voltage referencing in portable and battery-sensitive systems-emphasizing EEPROM-based trimming, fast enable/disable, and operation down to 1.8 V input.

FAQ

What is the minimum input voltage required for stable operation of LM4140ACMX-2.5/NOPB?

The LM4140ACMX-2.5/NOPB requires a minimum input voltage of VREF + 20 mV (2.52 V) at 1 mA load and 25°C, with 45 mV maximum dropout across 0°C to 70°C. At 1.8 V input, it supports only the 1.024 V and 1.25 V variants-not the 2.5 V version. Therefore, LM4140ACMX-2.5/NOPB must be supplied with ≥2.52 V for guaranteed regulation, though 2.7 V or higher is recommended for margin.

Does LM4140ACMX-2.5/NOPB require an external output capacitor, and what type is recommended?

Yes, LM4140ACMX-2.5/NOPB requires a minimum 1 µF output capacitor connected between VREF and GND for loop stability and transient response. TI validates solid tantalum (e.g., Kemet T491A105M010AS) and multilayer ceramic capacitors (e.g., Murata GRM42-6Y5V225Z16) meeting ESR specifications in Figures 22–24 of SNVS053F. Ceramic types must be ≥0.2 µF and selected for stable capacitance vs. temperature.

How does the enable function work on LM4140ACMX-2.5/NOPB, and what happens to the output during shutdown?

The enable pin (Pin 3) controls LM4140ACMX-2.5/NOPB operation: driven high (≥0.8×VIN) for normal mode, grounded for shutdown. During shutdown, LM4140ACMX-2.5/NOPB actively discharges the output capacitor to GND via internal circuitry, reducing VREF to zero within microseconds and lowering supply current to ≤1 µA. This prevents residual voltage at the output and enables fast wake-up (<200 µs).

What is the output noise specification of LM4140ACMX-2.5/NOPB, and how does it scale with output voltage?

LM4140ACMX-2.5/NOPB delivers 2.2 µV_PP (0.1–10 Hz) output noise, measured on the 1.024 V variant. Per datasheet Section 6.5 Note 7, noise scales linearly with VREF; thus, for the 2.5 V version, expected noise is (2.5 / 1.024) × 2.2 µV_PP ≈ 5.4 µV_PP. This remains among the lowest noise figures for 2.5 V references in SOIC-8 packaging.

Can LM4140ACMX-2.5/NOPB drive an ADC reference input directly, and what is its maximum output current capability?

Yes, LM4140ACMX-2.5/NOPB can directly drive most precision ADC reference inputs. Its VREF pin sources and sinks up to ±8 mA, sufficient for driving typical 16-bit SAR ADCs (e.g., ADS8860: 1 µA max input current) and buffered op-amp reference networks. For loads exceeding 8 mA, external boost circuits (e.g., Figure 30 in SNVS053F) are required-LM4140ACMX-2.5/NOPB itself is not rated for continuous >8 mA output.