Diodes Incorporated ZTL431AH6TA

Overview

ZTL431AH6TA from Diodes Incorporated is a precision adjustable shunt regulator in SOT363 package, functioning as a 2.5 V reference with 1% initial tolerance at +25°C, 0.2 Ω typical dynamic output impedance, and 1 mA–100 mA sink current capability. It replaces Zener diodes in feedback loops of linear regulators, opto-coupler-based isolated power supplies, and overvoltage protection circuits across industrial and automotive power systems.

For engineers reviewing the ZTL431AH6TA datasheet, ZTL431AH6TA pinout, ZTL431AH6TA application, or ZTL431AH6TA equivalent, key selection criteria include its -40°C to +125°C operating range, 2.5 V reference voltage stability over temperature, SOT363 6-pin footprint compatibility, and functional equivalence to TL431 with extended voltage rating up to 20 V cathode-anode.

Technical Context

The ZTL431AH6TA operates as a three-terminal shunt regulator where the REF pin senses voltage via external resistive divider, triggering cathode current sink to maintain precise 2.5 V reference at the internal bandgap node. Its architecture integrates a high-gain transconductance amplifier driving an NPN output stage, enabling stable regulation with minimal external components.

It achieves ±14 mV reference deviation over -40°C to +125°C, supports 100 mA max cathode current, and exhibits <0.5 Ω dynamic output impedance at DC-critical for low-noise feedback paths in isolated DC-DC converters and voltage-monitoring circuits requiring tight tolerance and thermal robustness.

Key Specifications

Pinout & Package

SOT363 (SC70-6) package: 6-pin surface-mount, 2.1 mm × 2.0 mm × 1.1 mm body, 0.65 mm pitch, lead-free and RoHS-compliant. Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Reference, Pins 4–6 = NC (internally connected to substrate; must be left floating or tied to Anode).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBVR, ZTL431AH6TA offers wider temperature range and lower VKA rating; compared with ZTL431BH6TA, it trades 0.5% tolerance for lower cost while retaining identical thermal performance and package compatibility.

Availability

ZTL431AH6TA is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, and telecom DC-DC converters requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for ZTL431AH6TA 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 power management, signal integrity, and protection solutions for industrial, automotive, and computing markets.

ZTL431 belongs to Diodes' precision reference product line, engineered specifically for cost-sensitive yet thermally demanding shunt regulation tasks where TL431 drop-in replacement with extended temperature capability is required.

FAQ

What is the maximum cathode-to-anode voltage for ZTL431AH6TA?

The absolute maximum cathode voltage (VKA) is 20 V relative to the anode pin. Exceeding this rating risks permanent device failure. The recommended operating range is VREF (2.5 V) to 20 V, making it suitable for 12 V and 15 V rail monitoring but not for 24 V or 48 V systems without external clamping.

Can ZTL431AH6TA replace a standard 2.5 V Zener diode directly?

Yes-it functions as a 2.5 V Zener substitute with superior performance: 1% initial tolerance versus typical 5% Zener tolerance, 0.2 Ω dynamic impedance versus 10–100 Ω for Zeners, and stable operation from -40°C to +125°C without derating. No circuit modification is needed beyond ensuring minimum 1 mA cathode current.

Why are pins 4–6 labeled NC but require connection to anode?

Pins 4–6 are internally bonded to the silicon substrate. Leaving them floating may cause latch-up or instability due to parasitic capacitance. The datasheet mandates connecting them to Pin 1 (anode) or leaving them unconnected only if the PCB layout guarantees no capacitive coupling-best practice is direct tie to anode for robust ESD and thermal performance.

Is ZTL431AH6TA compatible with TL431-based PCB layouts?

No-SOT363 (6-pin) pinout differs fundamentally from TL431's TO-92, SO-8, or SOT-23 packages. Pin 1 (Anode), Pin 2 (Cathode), and Pin 3 (Reference) match functional roles but occupy different locations. Direct replacement requires PCB redesign; however, schematic-level substitution is fully compatible with identical external resistor networks.