STMicroelectronics TL1431CCT

Overview

TL1431CCT from STMicroelectronics is an adjustable shunt voltage reference IC with 0.4% initial voltage precision, 2.5 V nominal reference input voltage, and guaranteed operation from −20 °C to +70 °C. It delivers 1–100 mA sink current capability, 0.22 Ω typical dynamic impedance, and supports output voltage programming from 2.5 V to 36 V using two external resistors. It is used in precision feedback loops of isolated DC-DC converters and linear regulators.

For engineers reviewing the TL1431CCT datasheet, TL1431CCT pinout, TL1431CCT application, or TL1431CCT equivalent, key selection criteria include temperature stability over industrial range, low dynamic impedance for loop stability, cathode current regulation threshold, reference input current budget, and SOT323-6L package compatibility with high-density PCB layouts.

Technical Context

The TL1431CCT implements a bandgap-based shunt reference architecture with internal error amplifier and NPN pass transistor. Its reference input (REF) senses voltage via external resistor divider, while cathode (K) and anode (A) terminals form the regulated shunt path. The device operates as a 2-terminal programmable zener replacement but requires ≥0.5 mA minimum cathode current to maintain regulation.

It features a 1.5–3 µA reference input current (I_REF) across temperature, ±13 ppm/°C max temperature coefficient, and −2 to −1.1 mV/V line regulation sensitivity. Dynamic impedance remains ≤0.5 Ω up to 100 mA cathode current at frequencies ≤1 kHz, enabling stable compensation in flyback and buck-derived topologies.

Key Specifications

Pinout & Package

SOT323-6L plastic surface-mount package (3.0 × 1.7 mm footprint, 0.95 mm pitch, 1.0 mm max height); thermally enhanced for 565 mW power dissipation at T_amb = 25 °C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDT, TL1431CCT trades precision and temperature range for smaller SOT323-6L size and lower cost; compared with LM4040CIM3-ADJ, it provides full 2.5–36 V adjustability at the expense of higher I_REF, making it suitable for feedback-critical rather than ultra-low-power applications.

Availability

TL1431CCT is available at Aetrix Electronics and suitable for isolated DC-DC converters, programmable linear regulators, and overvoltage protection circuits requiring stable component supply and long-term manufacturability.

Supply support for TL1431CCT 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 management ICs, analog components, and MEMS sensors for industrial, automotive, and consumer markets.

The TL1431 product line delivers precision programmable shunt references optimized for feedback control in switch-mode power supplies, offering scalable accuracy grades and multiple package options for cost- and space-constrained designs.

FAQ

What is the minimum cathode current required for TL1431CCT to maintain regulation?

The TL1431CCT requires a minimum cathode current of 0.5 mA to sustain regulation, as specified in Table 4 of the datasheet. Below this threshold, the reference voltage deviates significantly from its nominal 2.5 V value. This parameter is critical for light-load stability in flyback converters and must be ensured by proper sizing of the feedback resistor divider.

Can TL1431CCT be used in automotive applications?

No - TL1431CCT is rated for −20 °C to +70 °C operation and is not qualified to AEC-Q100. For automotive use, ST offers the TL1431IYDT variant, which is rated for −40 °C to +125 °C and undergoes automotive-grade qualification including AEC-Q100 stress testing and advanced screening per AEC-Q001/Q002.

How does the SOT323-6L package affect thermal performance compared to SO-8?

The SOT323-6L package has a junction-to-ambient thermal resistance (R_thJA) of 221 °C/W versus 85 °C/W for SO-8, limiting its maximum continuous power dissipation to 565 mW at 25 °C ambient. Designers must verify that worst-case cathode current × (V_K − V_A) stays within this limit and consider PCB copper area or airflow if operating near thermal limits.

What is the function of the three NC pins on the TL1431CCT SOT323-6L package?

Pins 4, 5, and 6 of the TL1431CCT SOT323-6L package are internally unconnected (NC). They serve mechanical and packaging purposes only - improving mold integrity and die attach stability - and must remain electrically floating. No routing, grounding, or soldering is required or recommended for these pins.