STMicroelectronics TL431ACCT

Overview

TL431ACCT from STMicroelectronics is an AEC-Q100 qualified automotive-grade adjustable shunt voltage reference IC, configured in SOT323-6 package with 1% initial voltage accuracy (2.5 V nominal), operating across –40 °C to +125 °C, delivering 1–100 mA sink current and featuring 0.22 Ω typical dynamic impedance for precision feedback in isolated DC-DC converters and battery management systems.

For engineers reviewing the TL431ACCT datasheet, TL431ACCT pinout, TL431ACCT application, or TL431ACCT equivalent, key selection considerations include its automotive temperature range, 1% V_REF tolerance at 25 °C, SOT323-6 thermal resistance (R_thJA = 221 °C/W), and compatibility with external resistor programming for output voltages from 2.5 V to 36 V.

Technical Context

The TL431ACCT implements a precision 2.5 V bandgap reference with internal error amplifier and NPN output stage, functioning as a programmable shunt regulator where cathode-anode voltage is set by external resistive divider connected to the REF pin. Its operation requires minimum 0.5 mA cathode current for regulation and supports stable operation with capacitive loads up to 10 µF.

It features low dynamic impedance (0.22 Ω typ.) over 1–100 mA cathode current range and exhibits <±30 mV reference voltage deviation across –40 °C to +125 °C, with –2.7 to –1.4 mV/V line regulation sensitivity to cathode-anode voltage changes.

Key Specifications

Pinout & Package

SOT323-6 plastic surface-mount package with 0.65 mm pitch, 1.8–2.2 mm × 1.15–1.35 mm body, and 0.10–0.40 mm lead length; optimized for space-constrained automotive PCBs and thermally demanding applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431CCT and TL431ACL3T, the TL431ACCT uniquely combines automotive qualification, 1% accuracy, and SOT323-6's balanced thermal performance (221 °C/W) with noise-suppressing NC pins-making it optimal for high-reliability, space-constrained automotive power designs.

Availability

TL431ACCT is available at Aetrix Electronics and suitable for automotive power conversion, industrial isolated supplies, battery management systems, and programmable protection circuits requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TL431ACCT 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for automotive, industrial, and consumer markets.

The TL431 product line delivers precision programmable shunt references engineered for high-reliability feedback control in automotive power systems, industrial SMPS, and safety-critical voltage monitoring applications.

FAQ

What is the maximum power dissipation for TL431ACCT in SOT323-6 package?

The absolute maximum cathode-anode voltage is 37 V, and maximum continuous cathode current is 100 mA. With R_thJA = 221 °C/W and T_J(max) = 150 °C, the practical power limit is ~300 mW at 25 °C ambient. Derating is required above 25 °C; at 85 °C ambient, max dissipation drops to ~150 mW to maintain safe junction temperature.

Can TL431ACCT replace TL431ACD in SO-8 footprint designs?

No - TL431ACCT uses SOT323-6 (1.8 × 1.35 mm), while TL431ACD uses SO-8 (4.9 × 6.0 mm). They are not pin-compatible or drop-in replacements. Layout redesign and thermal analysis are required due to differing R_thJA (221 vs. 85 °C/W) and current-handling capability under identical power conditions.

Does TL431ACCT require an external capacitor for stability?

No external capacitor is required for basic regulation, but a 1 nF ceramic capacitor between REF and Anode is recommended to suppress high-frequency noise. The device remains stable with capacitive loads up to 10 µF on the Cathode node, enabling direct connection to output filter capacitors in SMPS designs without oscillation risk.

How does the 1% accuracy of TL431ACCT compare to TL431B variants?

TL431ACCT offers 1% V_REF accuracy at 25 °C and ±30 mV total deviation over –40 °C to +125 °C. TL431B variants provide tighter 0.5% initial accuracy but are only offered in SOT23-3 (e.g., TL431BL3T) - sacrificing thermal performance (R_thJA = 248 °C/W) and package-level noise immunity compared to TL431ACCT's SOT323-6 with three NC pins.