Texas Instruments TLVH431AQPK

Overview

TLVH431AQPK from Texas Instruments is a low-voltage adjustable precision shunt regulator in SOT-89-3 package, delivering 1.24 V reference voltage with ±0.5% initial tolerance at 25°C, 100 μA minimum cathode current for regulation, and operation from –40°C to +125°C. It functions as an error amplifier or comparator with integrated reference in isolated flyback SMPS feedback loops and low-voltage Zener replacement applications.

For engineers reviewing the TLVH431AQPK datasheet, TLVH431AQPK pinout, TLVH431AQPK application, or TLVH431AQPK equivalent, key selection criteria include its 1.24 V reference accuracy, ultra-low 100 μA regulation threshold, 0.25 Ω dynamic impedance, and SOT-89 thermal performance (R_θJA = 52°C/W) for high-reliability power rail monitoring and secondary-side regulation.

Technical Context

The TLVH431AQPK implements a three-terminal shunt-regulator architecture with internal 1.24 V bandgap reference and high-gain transconductance amplifier driving a Darlington output stage. Its open-loop mode enables precise voltage monitoring via comparator action, while closed-loop configuration with external resistors sets output voltage from 1.24 V to 18 V.

It operates with cathode-to-anode voltage down to 1.24 V and supports cathode current from 100 μA to 70 mA. Thermal stability is specified across –40°C to +125°C (Q-grade), and it requires no external compensation capacitor for stability in standard configurations.

Key Specifications

Pinout & Package

SOT-89-3 package (4.50 mm × 2.50 mm body size) with exposed thermal pad for enhanced heat dissipation; R_θJA = 52°C/W enables >300 mW power handling in standard PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431AQPK, TLVH431BQPK delivers identical accuracy at 25°C but guarantees tighter full-temperature V_REF deviation (≤31 mV), while TLVH432AQPK offers identical performance with inverted pinout - requiring PCB revision but enabling optimized feedback loop layout in dense power designs.

Availability

TLVH431AQPK is available at Aetrix Electronics and suitable for isolated SMPS feedback, voltage rail monitoring, Zener diode replacement, and precision ADC reference applications requiring stable component supply across automotive, industrial, and telecom end equipment.

Supply support for TLVH431AQPK 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 designing analog and embedded processing chips for industrial, automotive, and communications systems, with over 90 years of innovation in precision analog technology.

The TLVH431 family was developed to replace legacy TL431 in low-voltage, low-power applications-specifically targeting 3.3 V and below isolated power supplies, battery monitoring, and high-accuracy voltage references where headroom and quiescent current are critical.

FAQ

What is the reference voltage tolerance of TLVH431AQPK at 25°C?

The TLVH431AQPK has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 1.24 V nominal V_REF with bounds of 1.234 V to 1.246 V. This A-grade tolerance is confirmed in Section 5.6 of the TI SLVS555N datasheet and applies specifically to the AQ suffix variant. The TLVH431AQPK maintains this accuracy across its full operating temperature range of –40°C to +125°C, with total deviation bounded at 31 mV.

Does TLVH431AQPK require an external output capacitor for stability?

No, TLVH431AQPK is internally compensated and remains stable without an external capacitor between cathode and anode under standard operating conditions. Its architecture avoids phase-margin degradation seen in uncompensated shunt regulators. However, if a capacitive load is added-for example, to filter ripple-the device's phase margin versus capacitance curves (Figures 5-15 to 5-17) must be consulted to select values that maintain ≥45° phase margin at the target load current and cathode voltage.

What is the minimum cathode current required for regulation in TLVH431AQPK?

The TLVH431AQPK requires a minimum cathode current of 100 μA to maintain regulation, as specified in Section 5.5 (IK(min)) of the datasheet. This value is guaranteed over the full –40°C to +125°C temperature range. Operating below this threshold risks loss of regulation, increased output impedance, and degraded reference accuracy-particularly critical in battery-backed or ultra-low-power monitoring circuits where cathode current may dip near this limit.

How does TLVH431AQPK differ from TLVH432AQPK in pin configuration?

TLVH431AQPK uses Pin 1 = CATHODE, Pin 2 = ANODE, Pin 3 = REF in the SOT-89 package, whereas TLVH432AQPK uses Pin 1 = REF, Pin 2 = ANODE, Pin 3 = CATHODE. This reversal means TLVH432AQPK is not pin-compatible with TLVH431AQPK-PCB layout changes are mandatory. Both share identical electrical specifications, thermal ratings, and Q-grade temperature range, making TLVH432AQPK a functional alternative only when board revision is feasible.

Can TLVH431AQPK be used as a comparator, and what design considerations apply?

Yes, TLVH431AQPK functions as a comparator with integrated 1.24 V reference in open-loop mode. Key design considerations include supplying ≥100 μA cathode current to ensure sufficient open-loop gain, biasing the REF pin with a resistive divider from the signal to be monitored, and ensuring the ANODE is connected to a stable reference potential (typically ground). The device's sharp turn-on characteristic and low input current (0.1–0.5 μA) enable fast, low-power threshold detection without external components.