Diodes Incorporated LM4040C33FTA

Overview

LM4040C33FTA from Diodes Incorporated is a precision 3.3V shunt voltage reference in SOT23 package, rated for ±0.5% initial tolerance at +25°C, 20ppm/°C max temperature coefficient over –40°C to +125°C, and stable operation from 60µA to 15mA reverse current. It serves as a compact, low-noise (35µVRMS, 10Hz–10kHz) reference in battery-powered analog signal chains and portable power monitoring circuits.

For engineers reviewing the LM4040C33FTA datasheet, LM4040C33FTA pinout, LM4040C33FTA application, or LM4040C33FTA equivalent, key selection criteria include its guaranteed 3.3V output stability under varying load current, capacitive-load immunity, and compatibility with space-constrained PCB layouts requiring micro-power precision references.

Technical Context

The LM4040C33FTA operates as a two-terminal bandgap shunt reference, conducting reverse current to maintain a stable 3.3V cathode-to-anode voltage. Its internal architecture eliminates need for external output capacitance and tolerates wide capacitive loading without oscillation.

It delivers specified performance across –40°C to +125°C ambient, with dynamic impedance of 0.9Ω at 1mA/120Hz and long-term stability of 120ppm over 1000 hours. Thermal hysteresis is limited to 0.08% over full temperature swing.

Key Specifications

Pinout & Package

SOT23-3 surface-mount package (JEDEC TO-236AB); 2.4mm × 1.3mm footprint; thermal resistance θ_JA = 380°C/W; RoHS-compliant, halogen-free molding compound.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431ACDBVR and MAX6003EUR+T, the LM4040C33FTA offers optimal balance of fixed 3.3V convenience, ultra-low 60µA operating current, and proven capacitive-load stability-making it preferred for battery life–sensitive, space-limited, and production-ready analog systems.

Availability

LM4040C33FTA is available at Aetrix Electronics and suitable for battery-powered sensors, portable medical monitors, precision data acquisition systems, and industrial PLC analog input modules requiring stable component supply with full traceability and lifecycle support.

Supply support for LM4040C33FTA 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

Diodes Incorporated is a global semiconductor manufacturer specializing in discrete, analog, and mixed-signal solutions, with emphasis on reliability, efficiency, and miniaturization for industrial, computing, and consumer markets.

The LM4040 series belongs to Diodes' precision analog portfolio, engineered specifically for applications demanding stable, low-drift, micro-power voltage references in compact surface-mount packages.

FAQ

What is the minimum operating current for LM4040C33FTA at –40°C?

The minimum operating current is 70µA at –40°C to +125°C ambient, per Electrical Characteristics table. Below this current, regulation degrades beyond ±0.5% tolerance; design must ensure series resistor limits maximum current to ≤15mA while maintaining ≥70µA across worst-case temperature and supply conditions.

Can LM4040C33FTA drive a 100nF ceramic capacitor directly?

Yes - the device is explicitly designed to remain stable with any capacitive load, including 100nF ceramic capacitors. No series resistance or damping network is required, unlike many older shunt references. This is confirmed in the "No Output Capacitor Required" feature and Application Information section.

Is pin 3 (NC) electrically connected internally in the SOT23 package?

Yes - pin 3 is the die attach pad and forms an electrical connection to the silicon substrate. The datasheet mandates that pin 3 be left floating or tied to pin 2 (cathode); connecting it to ground or other potentials may cause malfunction or damage due to unintended substrate biasing.

How does LM4040C33FTA compare to LM4040B33FTA in long-term stability?

Both grades specify identical long-term stability: 120ppm over 1000 hours at 100µA. The difference lies solely in initial tolerance (±0.2% for B-grade vs. ±0.5% for C-grade) and temperature coefficient distribution - not aging behavior. System-level drift is dominated by tempco and thermal hysteresis, not grade-dependent lifetime drift.