Texas Instruments TL432AQPK

Overview

TL432AQPK from Texas Instruments is a precision programmable shunt voltage reference in SOT-89 package, delivering 2.495 V nominal reference voltage with ±0.5% initial accuracy at 25°C, 14–34 mV total temperature drift over −40°C to +125°C, and 0.2 Ω dynamic impedance - used for feedback regulation in isolated DC/DC converters and industrial power supplies.

For engineers reviewing the TL432AQPK datasheet, TL432AQPK pinout, TL432AQPK application, or TL432AQPK equivalent, key selection criteria include automotive-grade temperature range (−40°C to 125°C), A-grade (1%) initial tolerance, SOT-89 thermal performance (R_θJA = 52°C/W), and TL432-specific pin configuration versus TL431.

Technical Context

The TL432AQPK implements a three-terminal adjustable shunt regulator architecture with an internal error amplifier, reference, and output stage. It operates as a precision voltage-controlled current sink where cathode current (I_KA) is regulated based on the voltage at the REF pin relative to ANODE, enabling stable closed-loop feedback in switching power supplies.

Unlike the TL431, the TL432AQPK uses a distinct pinout: Pin 1 = REF, Pin 2 = ANODE, Pin 3 = CATHODE - requiring PCB layout revision when substituting. Its Q-temp grade guarantees operation across −40°C to +125°C with specified VI(dev) ≤ 34 mV and I_min = 0.4 mA for regulation onset.

Key Specifications

Pinout & Package

SOT-89 (PK) package: 3-pin thermally enhanced plastic surface-mount package with exposed pad for improved heat dissipation; body size 4.5 mm × 2.5 mm × 1.5 mm; R_θJA = 52°C/W enables >500 mW power handling at TA = 25°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431AQPK, TL432AQPK offers identical accuracy and temperature performance but mandates layout change due to pin reversal; compared with TLVH431AQDBVR, it delivers tighter tolerance, lower drift, and higher reference voltage - making it preferable for industrial and automotive power regulation where precision and thermal robustness are critical.

Availability

TL432AQPK is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC adapters, and servo drive control modules requiring stable component supply with automotive-grade temperature qualification and long-term lifecycle support.

Supply support for TL432AQPK 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in precision reference design.

The TL43x family was engineered for high-accuracy, low-drift voltage regulation in isolated power supplies and feedback control systems - emphasizing thermal stability, wide operating range, and robustness in harsh environments.

FAQ

What is the reference voltage tolerance of TL432AQPK at 25°C?

The TL432AQPK has ±1% initial reference voltage tolerance at 25°C, corresponding to the "A" grade designation. This means its V_ref falls between 2.470 V and 2.520 V under standard test conditions (V_KA = V_ref, I_KA = 10 mA). This tolerance is guaranteed and tested during manufacturing, and TL432AQPK maintains this specification across its full −40°C to +125°C operating range.

How does TL432AQPK differ from TL431AQPK in pin configuration?

TL432AQPK uses a reversed pinout versus TL431AQPK in the SOT-89 (PK) package: TL432AQPK is REF–ANODE–CATHODE (Pin 1–2–3), while TL431AQPK is CATHODE–ANODE–REF. This difference is intentional and documented in TI's device comparison table. Using TL432AQPK in a TL431-layout board will result in incorrect regulation or device damage. TL432AQPK must be placed with correct orientation per its PK package marking and datasheet diagram.

What is the minimum cathode current required for regulation in TL432AQPK?

The TL432AQPK requires a minimum cathode current (I_min) of 0.4 mA to maintain regulation, as specified in Section 6.10 of the datasheet. Below this threshold, the device exits active regulation and behaves as an open circuit. This value is consistent across all TL432Q-grade variants and is validated over the full −40°C to +125°C temperature range. Designers must ensure external circuitry delivers ≥0.4 mA to the CATHODE pin under all operating conditions.

Can TL432AQPK replace a Zener diode in power supply designs?

Yes, TL432AQPK is explicitly designed as a precision replacement for Zener diodes in shunt regulation applications. Unlike standard Zeners, TL432AQPK offers ±1% initial accuracy, 0.2 Ω dynamic impedance, sharp turn-on, and guaranteed −40°C to +125°C operation - resulting in significantly better line/load regulation, lower temperature drift, and improved transient response. Its REF pin allows precise voltage setting via resistive dividers, eliminating Zener voltage binning and tolerance stacking issues.

What thermal performance does the SOT-89 package provide for TL432AQPK?

The TL432AQPK in SOT-89 (PK) package has a junction-to-ambient thermal resistance (R_θJA) of 52°C/W, per Table 6.3. With a maximum junction temperature of 150°C and 25°C ambient, this allows up to ~2.4 W of power dissipation before thermal limiting - though practical continuous dissipation is ~500 mW considering derating. The exposed pad enhances heat transfer to the PCB copper, making TL432AQPK suitable for high-reliability industrial power applications where thermal margin is critical.