Texas Instruments LM4121IM5-ADJ/NOPB

Overview

LM4121IM5-ADJ/NOPB from Texas Instruments is a precision micropower adjustable voltage reference IC in SOT-23-5 package, delivering 1.216 V nominal output with ±0.2% initial accuracy (Grade A), 50 ppm/°C temperature coefficient, ±5 mA source/sink capability, and 160 µA typical supply current - used as a stable reference in portable battery-powered instrumentation and low-voltage analog signal chains.

For engineers reviewing the LM4121IM5-ADJ/NOPB datasheet, LM4121IM5-ADJ/NOPB pinout, LM4121IM5-ADJ/NOPB application, or LM4121IM5-ADJ/NOPB equivalent, key selection considerations include its adjustable output architecture, enable-controlled power-down mode (<2 µA), low dropout operation down to 1.8 V input, and compatibility with ceramic output capacitors ≥0.022 µF.

Technical Context

The LM4121IM5-ADJ/NOPB implements a bandgap-based reference core with an external feedback network via the ADJ pin, enabling programmable output voltages using two resistors per V_OUT = V_REF(1 + R1/R2) − I_BIAS·R1. Its internal enable circuitry accepts TTL/CMOS-compatible logic thresholds (V_H = 1.5 V, V_L = 0.4 V) and requires ~6 µA pull-up for activation.

It operates across −40°C to +85°C ambient, supports load currents from −5 mA to +5 mA, maintains stability with 0.022–0.047 µF ceramic output capacitors (ESR ≤0.5 Ω), and exhibits 20 µV_PP (0.1–10 Hz) and 30 µV_RMS (10 Hz–10 kHz) output noise - all while consuming only 160 µA quiescent current in active mode.

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.9 mm × 1.6 mm × 1.45 mm body, gull-wing leads, RoHS-compliant matte tin lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM4121IM5-ADJ/NOPB, LM4040CIM3-ADJ/NOPB offers lower cost but demands higher minimum current and lacks enable control, while MAX6126ASA21+T delivers better temperature stability at the expense of adjustability and power management - making LM4121IM5-ADJ/NOPB optimal for battery-constrained, programmable-reference designs.

Availability

LM4121IM5-ADJ/NOPB is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered data loggers, and industrial process transmitters requiring stable component supply with guaranteed long-term sourcing.

Supply support for LM4121IM5-ADJ/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, designing analog and embedded processing chips for industrial, automotive, and consumer applications.

The LM4121 product line delivers precision, low-power voltage references optimized for battery-operated instrumentation, portable test equipment, and energy-conscious signal-chain architectures.

FAQ

What is the minimum input voltage required for stable operation of the LM4121IM5-ADJ/NOPB?

The LM4121IM5-ADJ/NOPB operates stably with input voltages as low as 1.8 V at full 5 mA load, and down to 1.5 V under light loads. This low dropout capability enables direct use with single-cell Li-ion (2.7–4.2 V) or two-cell alkaline (2.4–3.2 V) batteries without pre-regulation. The device maintains specified accuracy and noise performance across this range when paired with ≥0.022 µF ceramic output capacitance.

How does the ADJ pin function in the LM4121IM5-ADJ/NOPB, and what is its bias current?

The ADJ pin on the LM4121IM5-ADJ/NOPB serves as the feedback node for setting output voltage via an external resistor divider. It sources a small, temperature-dependent bias current of 15–40 nA (typical 25 nA), which flows out of the pin and must be accounted for in the V_OUT calculation: V_OUT = V_REF(1 + R1/R2) − I_BIAS·R1. This current introduces a small gain error unless compensated, especially with high-value resistors (>500 kΩ).

Can the LM4121IM5-ADJ/NOPB be used with ceramic output capacitors, and what is the minimum value?

Yes, the LM4121IM5-ADJ/NOPB is explicitly designed for stability with ceramic output capacitors ranging from 0.022 µF to 0.047 µF. The minimum recommended value is 0.022 µF (X7R dielectric); values below this risk oscillation. Larger ceramics (>0.047 µF) require careful validation, and tantalum capacitors may be used up to 1 µF if a 50 pF capacitor is added between OUT and ADJ pins.

What is the power-down behavior of the LM4121IM5-ADJ/NOPB when the EN pin is asserted?

When the EN pin of the LM4121IM5-ADJ/NOPB is pulled below 0.4 V, the device enters power-down mode, reducing supply current to <2 µA (typical 1 µA at VIN = 12 V). During this state, the output is disabled and high-impedance. Recovery time from power-down to full regulation is typically 10 µs, as shown in Figure 13 of the datasheet. The EN pin draws only 0.1–15 µA depending on logic level.

Is the LM4121IM5-ADJ/NOPB suitable for use in extended temperature applications beyond −40°C to +85°C?

The LM4121IM5-ADJ/NOPB is characterized and guaranteed over the industrial temperature range of −40°C to +85°C ambient. While certain parameters - including temperature coefficient (50 ppm/°C) and thermal hysteresis (0.5 mV/V) - are ensured from −40°C to +125°C junction temperature, full electrical specifications are not guaranteed above +85°C ambient. For extended-range operation, contact Texas Instruments for qualified variants or application-specific validation guidance.