Diodes Incorporated ZTL431BQFFTA

Overview

ZTL431BQFFTA from Diodes Incorporated is an automotive-grade adjustable precision shunt regulator in SOT23F package, featuring 0.5% initial reference voltage tolerance (2.5 V), -40°C to +125°C operating range, 0.2 Ω typical dynamic output impedance, and 1–100 mA sink current capability. It functions as a programmable voltage reference or error amplifier in feedback loops for linear regulators, opto-coupler-based isolated power supplies, and overvoltage protection circuits.

For engineers reviewing the ZTL431BQFFTA datasheet, ZTL431BQFFTA pinout, ZTL431BQFFTA application, or ZTL431BQFFTA equivalent, key selection criteria include AEC-Q100 Grade 1 qualification, SOT23F thermal performance (θ_JA = 138°C/W), cathode voltage range (2.5–20 V), and stability with ≥4.7 nF anode–cathode capacitance.

Technical Context

This device operates as a three-terminal shunt regulator where the reference input (REF) senses voltage via external resistive divider, the cathode (K) sinks current to regulate output, and the anode (A) serves as common return. Its internal bandgap reference and op-amp comparator deliver stable 2.5 V threshold with <34 mV deviation across –40°C to +125°C.

Unlike standard TL431 variants, ZTL431BQFFTA uses SOT23F pinout (REF–A–K), supports 20 V max cathode voltage, and achieves 720 mW max power dissipation at T_A = +25°C due to improved thermal resistance. It requires no external compensation beyond minimum 4.7 nF anode–cathode capacitor for stability under capacitive loads.

Key Specifications

Pinout & Package

SOT23F package: 3-pin surface-mount, 2.9 mm × 2.4 mm × 0.9 mm body, gull-wing leads, RoHS-compliant green molding compound.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431BIDBVR, ZTL431BQFFTA delivers 2.8× higher power dissipation margin and guaranteed automotive reliability; versus ZTL432BQFFTA, it retains legacy REF–A–K pin compatibility critical for drop-in replacement in production boards.

Availability

ZTL431BQFFTA is available at Aetrix Electronics and suitable for automotive power management, isolated feedback control, and precision voltage monitoring requiring stable component supply across extended temperature ranges.

Supply support for ZTL431BQFFTA 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 manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability components for automotive, industrial, and computing markets.

ZTL431 series belongs to Diodes' Automotive Compliant shunt regulator product line, engineered specifically for AEC-Q100 Grade 1 environments where precision, thermal robustness, and PPAP documentation are mandatory.

FAQ

What is the maximum cathode voltage for ZTL431BQFFTA?

The absolute maximum cathode-to-anode voltage (V_KA) is 20 V. Operation beyond this risks permanent damage. For reliable long-term use, design cathode voltage within 2.5 V to 20 V range, with recommended derating to ≤18 V at +125°C junction temperature to maintain 1000-hour lifetime.

Can ZTL431BQFFTA replace TL431 in existing designs?

Yes, electrically-ZTL431BQFFTA matches TL431's functional behavior and reference voltage-but mechanical replacement requires verifying SOT23F footprint compatibility and thermal layout. Unlike TL431, it supports 20 V max V_KA and delivers superior thermal performance (138°C/W vs. 380°C/W), making it suitable for higher-power automotive implementations.

Why is a minimum 4.7 nF capacitor required between anode and cathode?

This capacitor ensures phase margin >45° across all operating conditions, preventing oscillation caused by parasitic inductance and load capacitance. Diodes' stability boundary analysis shows instability zones below 4.7 nF, especially with >100 nF output capacitance. Omitting it risks sustained ringing or latch-up in feedback loops.

How does the 0.5% reference tolerance impact system calibration?

With ±12.5 mV error at +25°C, ZTL431BQFFTA reduces initial calibration burden in closed-loop systems. In a 12 V output supply using 100 kΩ/20 kΩ divider, this translates to ±0.075 V output error-enabling single-point factory trim instead of multi-temperature calibration, cutting test time by ~35%.