Diodes Incorporated LM4040C41QFTA

Overview

LM4040C41QFTA from Diodes Incorporated is a precision micropower shunt voltage reference delivering 4.096V nominal output with ±0.5% 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 reverse current. It is AEC-Q100 qualified for automotive data acquisition and sensor signal conditioning where space-constrained SOT23 packaging and low-noise (64 µV_RMS, 10 Hz–10 kHz) performance are critical.

For engineers reviewing the LM4040C41QFTA datasheet, LM4040C41QFTA pinout, LM4040C41QFTA application, or LM4040C41QFTA equivalent, key selection criteria include its automotive-grade qualification, 4.096V reference accuracy, SOT23 package thermal resistance (380°C/W), and compatibility with capacitive loads without external compensation.

Technical Context

The LM4040C41QFTA operates as a two-terminal bandgap-based shunt reference, requiring only an external series resistor to regulate voltage in feedback loops or ADC reference circuits. Its internal architecture maintains stability with up to 1 µF capacitive load and exhibits minimal voltage drift under varying supply and load conditions.

It achieves 64 µV_RMS noise over 10 Hz–10 kHz at 100 µA bias, dynamic impedance of 1.0 Ω at 1 mA/120 Hz, and long-term stability of 120 ppm over 1000 hours - all verified across –40°C to +125°C ambient.

Key Specifications

Pinout & Package

SOT23-3 surface-mount package (2.9 mm × 1.3 mm × 1.0 mm), with die attached to Pin 3 - requiring Pin 3 to 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 TLVH431AQDBVRQ1 and MAX6008AEUR+T, the LM4040C41QFTA delivers optimal balance of automotive qualification, fixed 4.096V accuracy, and SOT23 footprint - eliminating design complexity while meeting ASIL-B reference stability requirements.

Availability

LM4040C41QFTA is available at Aetrix Electronics and suitable for automotive data acquisition systems, battery monitoring units, ADAS camera power sequencing, and radar signal chain references requiring stable component supply across extended temperature and lifecycle demands.

Supply support for LM4040C41QFTA 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.

The LM4040Q series was developed specifically for AEC-Q100-compliant automotive systems requiring high-accuracy, low-drift voltage references in compact packages - targeting ECU, sensor interface, and safety-critical power management applications.

FAQ

What is the maximum reverse current the LM4040C41QFTA can safely handle?

The absolute maximum continuous reverse current is 20 mA per datasheet DS36989 Rev. 3–2. However, recommended operation limits current to 15 mA to maintain specified voltage accuracy and thermal reliability. Exceeding 15 mA risks exceeding the 330 mW power dissipation limit in SOT23 at elevated ambient temperatures.

Can Pin 3 of the SOT23 package be used as a separate ground connection?

No - Pin 3 is internally connected to the die substrate and electrically tied to the cathode (Pin 2). Per Diodes' layout guidance, Pin 3 must either be left floating or shorted to Pin 2. Using it as an independent terminal violates the device's mechanical construction and may cause parametric shift or failure.

Does the LM4040C41QFTA require a minimum load current to regulate properly?

Yes - it requires a minimum reverse current of 60 µA at +25°C (88 µA at +125°C) to maintain regulation within specification. Below this, the reference voltage deviates significantly; design must ensure the series resistor and load combination guarantees ≥60 µA under worst-case low-VS/high-IL conditions.

How does the LM4040C41QFTA perform under capacitive loading?

It remains stable with up to 1 µF of capacitive load on the cathode without external compensation - a key advantage over many shunt references. This is validated in the datasheet's "Typical Characteristics" section and enables direct connection to ADC reference inputs or op-amp feedback nodes without series resistance or isolation.