Texas Instruments LM4140BCM-1.2

Overview

LM4140BCM-1.2 from Texas Instruments is a high-precision, low-noise, low-dropout series voltage reference delivering 1.25 V output with ±0.1% initial accuracy, 3 ppm/°C temperature coefficient (A grade), and 20 mV typical dropout at 1 mA - designed for precision ADC/DAC biasing in portable instrumentation and battery-powered systems.

For engineers reviewing the LM4140BCM-1.2 datasheet, LM4140BCM-1.2 pinout, LM4140BCM-1.2 application, or LM4140BCM-1.2 equivalent, key selection considerations include enable-controlled shutdown (≤1 µA), ultra-low 2.2 µV_PP (0.1–10 Hz) noise, 1.8 V minimum input operation, and SOIC-8 package compatibility with standard PCB layout practices for analog signal integrity.

Technical Context

The LM4140BCM-1.2 uses EEPROM-trimmed CMOS DACs for curvature-corrected temperature compensation and output voltage trimming - enabling sub-bandgap 1.25 V output with industry-leading 3 ppm/°C drift over 0°C to 70°C. Its P-channel pass transistor architecture supports low dropout and reverse current protection.

It operates in two functional modes: normal regulation (EN = VIN) and shutdown (EN = GND), achieving full VREF restoration in <200 µs. The internal 1-µF output capacitor requirement ensures loop stability and transient response compliance per TI's validated ESR ranges for tantalum and ceramic capacitors.

Key Specifications

Pinout & Package

LM4140BCM-1.2 is housed in an 8-pin SOIC package (4.90 mm × 3.91 mm body size) with exposed pad not present; thermal resistance R_θJA = 119.3°C/W. Ground pins (1, 4, 7, 8) must all be connected to system ground for optimal noise and PSRR performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with REF3012AIDBZR and ADR3412ARJZ-R7, the LM4140BCM-1.2 delivers superior initial accuracy (±0.1% vs ±0.2%), lower tempco (3 vs 50/10 ppm/°C), lower noise (2.2 vs 3.5 µV_PP), and higher output drive (8 mA vs 5 mA), making it optimal for high-fidelity measurement systems where reference stability dominates overall error budget.

Availability

LM4140BCM-1.2 is available at Aetrix Electronics and suitable for portable instrumentation, precision data acquisition, and battery-powered medical devices requiring stable component supply with guaranteed long-term continuity.

Supply support for LM4140BCM-1.2 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 digital signal processing technologies, with leadership in precision analog ICs since 1930.

The LM4140 product line was engineered to deliver sub-bandgap precision references with EEPROM-based trimming for high-volume, high-accuracy applications including test equipment, industrial sensors, and portable medical electronics.

FAQ

What is the minimum input voltage required for stable operation of the LM4140BCM-1.2?

The LM4140BCM-1.2 requires a minimum input voltage of 1.27 V (1.25 V output + 20 mV typical dropout) at 1 mA load. For reliable operation across temperature and load, TI specifies 1.8 V as the absolute minimum recommended input voltage - ensuring margin for worst-case dropout (45 mV at 70°C) and line regulation effects. Below 1.8 V, output accuracy and regulation cannot be guaranteed.

Does the LM4140BCM-1.2 require an external output capacitor, and if so, what are the specifications?

Yes, the LM4140BCM-1.2 requires a mandatory 1 µF output capacitor between VREF (pin 6) and GND (pins 1/4/7/8) for loop stability and transient response. TI validates performance with solid tantalum (e.g., Kemet T491A105M010AS) or ceramic capacitors meeting ESR requirements: 0.5–5 Ω for 1 µF parts. Using less than 0.2 µF or outside the ESR range risks oscillation or overshoot during load steps.

How does the enable pin (EN) function on the LM4140BCM-1.2, and what happens during shutdown?

The LM4140BCM-1.2 EN pin (pin 3) is active-high: pulling it to GND disables the output and reduces supply current to ≤1 µA. During shutdown, the internal circuitry actively discharges the output capacitor to GND - preventing residual voltage hold-up. VREF restores fully within 200 µs after EN returns high. The pin must never float; tie to VIN if unused.

What is the output noise performance of the LM4140BCM-1.2, and how is it measured?

The LM4140BCM-1.2 delivers 2.2 µV_PP (peak-to-peak) output noise over the 0.1 Hz to 10 Hz bandwidth - the critical region for precision DC measurements. This value is measured with 1 µF output capacitor, 1 mA load, and VIN = 3 V at 25°C. Noise scales linearly with output voltage; thus, the 1.25 V version exhibits proportionally lower noise than higher-voltage variants like the 4.096 V option.

Can the LM4140BCM-1.2 drive a 10 kΩ load directly, and what is its maximum output current capability?

Yes, the LM4140BCM-1.2 can directly drive a 10 kΩ load at 1.25 V (125 µA), well within its ±8 mA output current specification. Its output stage is rated for sourcing up to 8 mA and sinking up to 8 mA, supporting direct interface with ADC reference inputs, op-amp buffers, and low-power comparators without external amplification.