Diodes Incorporated ZTL432AFTA

Overview

ZTL432AFTA from Diodes Incorporated is a 1% initial tolerance, adjustable precision shunt regulator in SOT23 package, delivering 2.5V reference voltage with ±14mV deviation over −40°C to +125°C, 0.2Ω typical dynamic output impedance, and 1–100mA sink current capability. It replaces standard zener diodes in feedback loops of linear regulators and opto-coupler-based isolated power supplies.

For engineers reviewing the ZTL432AFTA datasheet, ZTL432AFTA pinout, ZTL432AFTA application, or ZTL432AFTA equivalent, key selection criteria include its SOT23 pinout (Anode–Cathode–Ref), 2.5V reference accuracy at 10mA cathode current, thermal stability across automotive-grade temperature range, and compatibility with capacitive load stabilization per stability boundary guidance.

Technical Context

The ZTL432AFTA implements a bandgap-referenced error amplifier with internal 2.5V reference, configured as a three-terminal shunt regulator where cathode voltage is set by external resistor divider between cathode and reference pins. Its regulation requires minimum 0.4mA cathode current and maintains stable operation up to 20V cathode-anode voltage.

Unlike the ZTL431, the ZTL432 uses reversed pinout in SOT23 (Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Reference), enabling direct PCB layout reuse when upgrading from TL431-based designs requiring improved thermal performance or tighter reference tolerance.

Key Specifications

Pinout & Package

SOT23-3 package (JEDEC TO-236AB), 2.9mm × 1.3mm × 1.0mm body, gull-wing leads, RoHS-compliant matte tin lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL432ACDBVR, ZTL432AFTA offers extended temperature qualification and tighter production testing; compared with ZTL431AFTA, it enables drop-in replacement in TL432-compatible layouts while maintaining identical regulation performance.

Availability

ZTL432AFTA is available at Aetrix Electronics and suitable for automotive power management, industrial isolated SMPS, and telecom DC-DC converter designs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZTL432AFTA 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 automotive, industrial, and consumer markets.

The ZTL43x series belongs to Diodes' precision reference product line, designed specifically to replace legacy zener diodes in feedback and protection circuits where temperature stability, low output impedance, and extended ambient operation are critical.

FAQ

What is the correct SOT23 pinout for ZTL432AFTA?

Pin 1 is Anode (connected to ground or lowest potential), Pin 2 is Cathode (output node that sinks current), and Pin 3 is Reference (feedback input). This differs from ZTL431AFTA, which has Anode–Ref–Cathode ordering. Confirm orientation using the "32A" top-mark and notch indicator on the package.

Can ZTL432AFTA replace TL431 in existing designs?

Yes, electrically - but only if the PCB uses the TL432 pinout (Anode–Cathode–Ref). ZTL432AFTA matches TL432's pin configuration and exceeds TL431's max cathode voltage (20V vs. 36V) and temperature range (−40°C to +125°C vs. −40°C to +105°C). Verify stability with ≥4.7nF anode–cathode capacitance.

How does the 1% tolerance affect output voltage accuracy in a 5V regulator design?

With R1 = 10kΩ and R2 = 9.53kΩ, nominal output is 5.00V. At 25°C, 1% VREF tolerance contributes ±50mV error; combined with ±14mV tempco over −40°C to +125°C, total worst-case error is ±64mV (±1.28%). No additional calibration is needed for most industrial applications.

Is ZTL432AFTA suitable for use with capacitive loads above 100nF?

No - the stability boundary chart shows instability risk with >100nF at frequencies near 10kHz. For loads >4.7nF, add a 30Ω series resistor between cathode and capacitor. Loads >100nF require additional phase compensation or alternative topology; consult Figure 4 and stability test circuit on page 5 of DS33263 Rev. 17-2.