Diodes Incorporated LM4040D33FTA

Overview

LM4040D33FTA from Diodes Incorporated is a precision micropower shunt voltage reference delivering a nominal 3.3V reverse breakdown voltage with ±1% initial tolerance at +25°C, 100 ppm/°C max temperature coefficient over –40°C to +125°C, and stable operation across 60 µA to 15 mA cathode current - used in automotive sensor signal conditioning and ADC biasing circuits.

For engineers reviewing the LM4040D33FTA datasheet, LM4040D33FTA pinout, LM4040D33FTA application, or LM4040D33FTA equivalent, key selection criteria include its AEC-Q100 qualification, SOT23 package footprint, no-output-capacitor-required stability, and 35 µV_RMS noise (10 Hz–10 kHz) in low-power reference designs.

Technical Context

The LM4040D33FTA implements a bandgap-based shunt reference architecture optimized for automotive environments, maintaining regulation without external capacitors across load and supply variations. Its dynamic output impedance is 0.9 Ω at 1 mA and 120 Hz, enabling fast transient response in feedback loops.

It operates as a two-terminal device with anode and cathode terminals only, requiring no ground connection - simplifying PCB layout in isolated or floating reference applications. Thermal hysteresis is limited to 0.08% over –40°C to +125°C cycling, ensuring repeatable accuracy after thermal stress.

Key Specifications

Pinout & Package

LM4040D33FTA is housed in a standard SOT23-3 surface-mount package (JEDEC TO-236AB), with die attached to pin 3 - electrically connecting pins 2 and 3. Pin 3 must be left floating or tied to pin 2 per layout guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM4040D33FTA, TLVH431AQDBVRQ1 offers flexibility at the cost of accuracy and component count, while MAX6003EUR+T improves precision and drift but lacks AEC-Q100 validation - making LM4040D33FTA the optimal choice for production automotive systems requiring certified reliability and minimal footprint.

Availability

LM4040D33FTA is available at Aetrix Electronics and suitable for automotive sensor modules, engine control units, ADAS camera power supervision, and EV battery management systems requiring stable component supply under IATF 16949-controlled logistics.

Supply support for LM4040D33FTA 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 for automotive, industrial, and consumer markets, with ISO/TS 16949-certified manufacturing facilities.

The LM4040Q series was developed specifically for automotive-grade precision voltage referencing, targeting AEC-Q100 compliance, extended temperature operation, and robustness in harsh vehicle environments.

FAQ

What is the minimum cathode current required for regulation at –40°C?

The LM4040D33FTA requires a minimum cathode current of 70 µA at –40°C to maintain regulation within specification. This value is derived from the datasheet's "Minimum Operating Current" table for D-grade devices across the full temperature range, ensuring stable 3.3V output even in cold-start automotive conditions.

Can LM4040D33FTA drive a 10 nF capacitive load without oscillation?

Yes - the LM4040D33FTA is explicitly characterized for stability with capacitive loads up to at least 1 µF, and its internal compensation ensures unconditional stability with 10 nF. The datasheet confirms "excellent stability" with capacitive loads and shows no peaking in impedance vs. frequency plots up to 1 MHz at 100 µA bias.

Is pin 3 (die attach) electrically isolated in the SOT23 package?

No - pin 3 is internally connected to the silicon die substrate and forms a low-impedance bond to pin 2 (cathode). Per the datasheet's PCB layout guidance, pin 3 must either be left floating or shorted to pin 2; routing it independently risks violating internal electrical constraints and degrading regulation performance.

How does long-term stability affect calibration intervals in automotive ECUs?

With 120 ppm drift over 1000 hours, LM4040D33FTA contributes less than 0.012% voltage shift per 1000 hours of operation - translating to ~0.4 mV drift at 3.3V. This enables multi-year calibration intervals in ECUs, reducing service costs and supporting ASIL-B functional safety requirements for reference integrity.