Texas Instruments LM4140ACMX-2.5

Overview

LM4140ACMX-2.5 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 load. It features an enable pin for power management and supports portable instrumentation, precision data acquisition, and battery-powered systems requiring stable, low-drift references.

For engineers reviewing the LM4140ACMX-2.5 datasheet, LM4140ACMX-2.5 pinout, LM4140ACMX-2.5 application, or LM4140ACMX-2.5 equivalent, key selection criteria include initial accuracy, thermal drift, enable-controlled shutdown (≤1 µA), ultra-low 2.2 µV_PP (0.1–10 Hz) noise, and compatibility with 1 µF output capacitance for stability in precision ADC/DAC reference designs.

Technical Context

The LM4140ACMX-2.5 uses EEPROM-trimmed CMOS DACs for curvature-corrected temperature compensation and output voltage trimming-enabling higher resolution than conventional bandgap references. Its P-channel pass transistor architecture supports operation down to VIN = VREF + 20 mV (typical) at 1 mA over 0°C to 70°C.

It operates in two functional modes: normal regulation (EN = VIN) and shutdown (EN = GND), achieving full VREF restoration in <200 µs. The device requires a mandatory 1 µF output capacitor for loop stability and transient response, with ESR constraints validated for tantalum, ceramic, and electrolytic types.

Key Specifications

Pinout & Package

LM4140ACMX-2.5 is housed in an 8-pin SOIC package (4.90 mm × 3.91 mm body size) with exposed pad not electrically connected. 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 precision voltage reference applications.

Compared with LM4140ACMX-2.5, REF5025IDR and ADR4525BRZ offer superior initial accuracy and lower drift but lack integrated enable functionality and draw >4× more quiescent current-making LM4140ACMX-2.5 the optimal choice for battery-constrained, enable-driven precision systems.

Availability

LM4140ACMX-2.5 is available at Aetrix Electronics and suitable for precision data acquisition, portable instrumentation, and medical sensor interface applications requiring stable component supply, long-term parametric consistency, and automotive-qualified traceability.

Supply support for LM4140ACMX-2.5 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 leader specializing in analog, embedded processing, and digital signal technologies, with decades of leadership in precision analog ICs and reference design expertise.

The LM4140 family was engineered specifically for high-accuracy, low-power, low-voltage reference applications in portable, medical, and industrial systems-addressing the need for sub-bandgap outputs with EEPROM-based trimming.

FAQ

What is the minimum input voltage required for LM4140ACMX-2.5 to regulate at 2.5 V?

The LM4140ACMX-2.5 requires VIN ≥ VREF + 20 mV (typical) at 1 mA load and 25°C, i.e., ≥2.52 V. Over temperature (0°C to 70°C), dropout increases to 45 mV max, so VIN ≥2.545 V ensures regulation across full range. This low dropout enables direct use with 2.7 V or 3.3 V rails without intermediate regulation.

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

Yes-LM4140ACMX-2.5 mandates a 1 µF output capacitor between VREF and GND for loop stability and transient response. Verified capacitor types include surface-mount solid tantalum (e.g., Kemet T491A105M010AS), aluminum electrolytic (with ESR limits), and multilayer ceramic (≥0.2 µF, with ESR ≥0.1 Ω). Ceramic capacitors below 0.2 µF risk instability.

How does the enable pin of LM4140ACMX-2.5 behave during shutdown?

When EN is pulled low (<0.4 V), LM4140ACMX-2.5 enters shutdown, reducing supply current to ≤1 µA and discharging the output capacitor to GND via internal circuitry. VREF drops to near 0 V within microseconds. Upon EN rising above 0.8×VIN, VREF restores to 2.5 V in <200 µs-enabling rapid wake-up in duty-cycled systems.

Can LM4140ACMX-2.5 drive an ADC input directly without a buffer amplifier?

Yes-LM4140ACMX-2.5 can directly drive most SAR and sigma-delta ADC reference inputs. Its ±8 mA output capability exceeds typical ADC reference input currents (e.g., <100 µA for ADS8860). However, for high-speed ADCs with dynamic loading or long PCB traces, a unity-gain buffer is recommended to maintain PSRR and noise performance.

What is the long-term stability specification for LM4140ACMX-2.5?

LM4140ACMX-2.5 exhibits ≤60 ppm (0.006%) long-term stability after 1000 hours of operation at 25°C. This drift is measured under constant thermal and electrical stress and reflects inherent silicon aging-not PCB mechanical stress or thermal cycling effects, which require proper layout mitigation per TI's guidelines.