Texas Instruments LM4140ACM-4.1

Overview

LM4140ACM-4.1 from Texas Instruments is a high-precision, low-noise, low-dropout series voltage reference delivering 4.096 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, supports 1.8 V minimum input, and is optimized for precision data acquisition and battery-powered instrumentation.

For engineers reviewing the LM4140ACM-4.1 datasheet, LM4140ACM-4.1 pinout, LM4140ACM-4.1 application, or LM4140ACM-4.1 equivalent, key selection considerations include its ultra-low 2.2 µV_PP (0.1–10 Hz) noise, ≤1 µA shutdown current, 1 µF required output capacitor, and SOIC-8 package compatibility with space-constrained analog signal chains.

Technical Context

The LM4140ACM-4.1 uses EEPROM-trimmed CMOS DACs for curvature-corrected temperature compensation and output voltage trimming-enabling industry-leading 3 ppm/°C drift in the A grade. Its P-channel pass transistor architecture allows operation down to VIN = VREF + 20 mV (typical) while maintaining regulation across 0°C to 70°C.

It implements active output capacitor discharge during disable mode, achieving full turn-off of VREF and supply current in <200 µs. The enable pin accepts logic-level control (V_H ≥ 0.8×VIN, V_L ≤ 0.4 V) and must not float-requiring tie-to-VIN if unused.

Key Specifications

Pinout & Package

LM4140ACM-4.1 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 precision voltage reference applications.

Compared with REF5040IDR and ADR444BRZ, LM4140ACM-4.1 uniquely balances ultra-low power (265 µA active / 0.01 µA shutdown), integrated enable control, and production-grade 0.1% / 3 ppm/°C performance-making it optimal for portable, battery-aware precision systems where feature integration matters more than marginal noise reduction.

Availability

LM4140ACM-4.1 is available at Aetrix Electronics and suitable for portable instrumentation, precision data acquisition, and battery-powered sensors requiring stable component supply with guaranteed long-term continuity.

Supply support for LM4140ACM-4.1 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 specializing in analog, embedded processing, and high-reliability components for industrial, automotive, and communications markets.

The LM4140 series was designed to deliver high-accuracy, low-drift voltage references in compact packages for portable and precision measurement applications-addressing the need for sub-10 ppm/°C stability without laser trimming.

FAQ

What is the minimum input voltage required for LM4140ACM-4.1 to maintain regulation?

The LM4140ACM-4.1 requires a minimum input voltage of VREF + 20 mV (typical) at 1 mA load, i.e., 4.116 V. At 8 mA load, dropout rises to 270 mV (max), so VIN must be ≥4.366 V. This is specified in the Electrical Characteristics table under "Dropout voltage" for the 4.096-V option. Operation below this threshold causes output collapse and loss of reference integrity.

Does LM4140ACM-4.1 require an output capacitor, and what type is recommended?

Yes, LM4140ACM-4.1 requires a 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 requirements. Ceramic types must be selected carefully to avoid ESR below 0.1 Ω, which can cause oscillation.

How does the enable pin function on LM4140ACM-4.1, and what happens during shutdown?

The enable pin (Pin 3) controls LM4140ACM-4.1 operation: logic high (≥0.8×VIN) enables the reference; logic low (≤0.4 V) disables it. During shutdown, LM4140ACM-4.1 actively discharges the output capacitor to ground via internal circuitry, reducing VREF and supply current to near-zero within microseconds-ensuring clean, predictable power-down behavior.

What is the output noise specification for LM4140ACM-4.1, and how does it scale with voltage?

LM4140ACM-4.1 delivers 2.2 µV_PP (0.1–10 Hz) output noise, measured on the 1.024 V variant. Per datasheet Note (7), output noise is linearly proportional to VREF; thus, for the 4.096 V version, noise scales to approximately 8.8 µV_PP. This value is confirmed in TI's typical characteristics (Figure 11) and defines the fundamental noise floor limiting ADC effective resolution.

Can LM4140ACM-4.1 drive an 8 mA load continuously, and what is its short-circuit current limit?

Yes, LM4140ACM-4.1 is rated to source up to 8 mA continuously while maintaining output accuracy and thermal stability. Its short-circuit current is 8.5–35 mA (typ–max) at 25°C, rising to 40 mA (max) over 0°C–70°C. Sustained short-circuit operation is not recommended due to thermal stress; external current limiting is advised for fault-tolerant designs.