STMicroelectronics TS3431CIZ

Overview

TS3431CIZ from STMicroelectronics is a precision programmable shunt voltage reference with 0.25% initial accuracy (1.237–1.243 V at 25°C), adjustable output from 1.24 V to 24 V via external resistors, and guaranteed operation across –40°C to +125°C. It delivers 0.4–100 mA sink current and features low dynamic impedance (0.2–0.4 Ω) for stable regulation in feedback loops of isolated DC-DC converters.

For engineers reviewing the TS3431CIZ datasheet, TS3431CIZ pinout, TS3431CIZ application, or TS3431CIZ equivalent, key selection criteria include reference voltage tolerance over temperature (±21 mV from –40°C to +125°C), cathode-anode voltage range (1.24–24 V), minimum operating current (0.5 mA at full temperature range), and TO-92 package thermal resistance (R_thja = 200°C/W).

Technical Context

The TS3431CIZ implements a two-terminal shunt topology where the reference voltage is developed between Cathode and Anode, with the Reference pin sensing internal bandgap voltage. Its core function is error amplification in closed-loop regulation-comparing a scaled-down output voltage against its internal 1.24 V reference to adjust power stage duty cycle or current.

It operates as a three-terminal device in circuit: Cathode sinks current to ground or return path, Anode connects to regulated output node, and Reference provides high-impedance sense input. Temperature stability is achieved via curvature-compensated bandgap design, yielding 100 ppm/°C TC and <21 mV total drift over –40°C to +125°C.

Key Specifications

Pinout & Package

TS3431CIZ uses the TO-92 plastic through-hole package (3-pin, straight lead configuration), optimized for prototyping, manual assembly, and legacy board designs requiring mechanical robustness and thermal mass.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACZ and MAX6008AEUR+T, TS3431CIZ uniquely combines 0.25% accuracy, full –40°C to +125°C operation, 24 V adjustability, and TO-92 mechanical reliability-making it optimal for ruggedized industrial power and instrumentation where calibration integrity and thermal resilience are non-negotiable.

Availability

TS3431CIZ is available at Aetrix Electronics and suitable for isolated switch-mode power supplies, battery charging circuits, industrial sensor transmitters, and programmable lab equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TS3431CIZ 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The TS3431 belongs to ST's precision analog voltage reference product line, engineered specifically for high-stability feedback control in isolated power conversion and measurement systems where accuracy, temperature resilience, and long-term drift performance are critical.

FAQ

What is the maximum cathode-to-anode voltage the TS3431CIZ can withstand?

The TS3431CIZ has an absolute maximum cathode-to-anode voltage (V_KA) rating of 25 V. Exceeding this value risks permanent damage to the internal bandgap structure. In normal operation, the device regulates within 1.24–24 V, so design margins must ensure transient spikes remain below 25 V-typically enforced with clamping diodes or snubbers in high-voltage SMPS outputs.

Can TS3431CIZ replace TL431 in existing designs without modification?

Yes-TS3431CIZ is pin-compatible with TL431 in TO-92 (Pin 1=Cathode, Pin 2=Anode, Pin 3=Reference) and shares identical electrical interface behavior. However, due to its tighter 0.25% tolerance and lower temperature drift, system-level calibration may require adjustment if original TL431 design relied on worst-case tolerance stacking.

How does the Reference pin current affect feedback resistor selection?

The Reference pin draws ≤2 µA across –40°C to +125°C. To limit voltage error from this current to <0.1%, total divider resistance should be ≤12 kΩ (e.g., 10 kΩ + 2.2 kΩ). Higher values increase sensitivity to leakage and noise but reduce power loss-trade-offs validated per application's accuracy and noise floor requirements.

Why does TS3431CIZ specify both R_thjc and R_thja, and which matters most in TO-92 layout?

R_thjc (66°C/W) defines junction-to-case thermal resistance-relevant only if heatsinking the case directly. For standard TO-92 mounting, R_thja (200°C/W) governs total thermal path to ambient air. Layout must maximize copper area on Anode/Cathode pads and avoid enclosed enclosures to prevent exceeding 150°C junction temperature at 100 mA sink current.