Texas Instruments ATL431AQDBZR

Overview

ATL431AQDBZR from Texas Instruments is a precision adjustable shunt regulator with 2.5V reference voltage, 1% initial tolerance at 25°C (A grade), and automotive-grade temperature range (–40°C to +125°C). It delivers stable regulation from 2.5V to 36V using two external resistors, supports cathode currents from 35µA to 100mA, and features 0.3Ω max dynamic impedance - enabling use in secondary-side feedback loops of isolated flyback converters.

For engineers reviewing the ATL431AQDBZR datasheet, ATL431AQDBZR pinout, ATL431AQDBZR application, or ATL431AQDBZR equivalent, this page provides verified electrical parameters, SOT-23 pin mapping, thermal performance data, stability boundaries for capacitive loads, and validated alternative parts for automotive power management and isolated voltage referencing.

Technical Context

The ATL431AQDBZR operates as a three-terminal shunt regulator with internal 2.5V bandgap reference and high-gain error amplifier driving a Darlington output stage. Its open-loop comparator mode enables overvoltage monitoring, while closed-loop configuration with resistive divider achieves precise adjustable output regulation.

It is internally compensated for stability without external capacitance, exhibits <15mV total reference drift over –40°C to +125°C (Q grade), and maintains ≤0.3Ω dynamic impedance across 1mA–100mA cathode current - critical for tight regulation in low-power industrial and automotive SMPS designs.

Key Specifications

Pinout & Package

SOT-23 (DBZ) package: 2.90mm × 1.60mm body, 3-pin surface-mount, JEDEC MO-178 compatible.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBVR, ATL431AQDBZR cuts no-load current by >70% and extends operating temperature by 55°C; versus ATL431LIQDBZR, it trades 0.5% initial accuracy for lower cost while retaining identical thermal and dynamic impedance specs.

Availability

ATL431AQDBZR is available at Aetrix Electronics and suitable for automotive power management, industrial isolated SMPS, and precision voltage monitoring requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ATL431AQDBZR 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 company designing analog ICs, embedded processors, and system solutions for industrial, automotive, and communications markets.

The ATL43x product line delivers low-I_Q, high-accuracy shunt regulators optimized for secondary-side regulation in isolated power supplies and precision voltage referencing in harsh-temperature environments.

FAQ

What is the maximum cathode voltage rating for ATL431AQDBZR?

The absolute maximum cathode-to-anode voltage (V_KA) for ATL431AQDBZR is 40V. Operation above this voltage risks permanent damage. The recommended operating range is 2.5V to 36V, aligning with its function as an adjustable shunt regulator. This 36V upper limit ensures compatibility with common 24V and 36V industrial and automotive bus systems while maintaining safe margin below the 40V absolute maximum.

Does ATL431AQDBZR require an external capacitor for stability?

No, ATL431AQDBZR is internally compensated and remains stable without any external capacitor between cathode and anode. This eliminates a common failure point and simplifies PCB layout. However, if an output capacitor is used for filtering, stability boundaries depend on ESR and capacitance value - Figure 5-14 through 5-21 in the datasheet define safe operating regions for various VKA and IKA conditions.

How does the 1% reference tolerance of ATL431AQDBZR affect output voltage accuracy?

The 1% V_REF tolerance at 25°C (A grade) directly propagates into the final output voltage when using resistive feedback. For example, programming 12V output with R1/R2 yields ±1% base error before considering resistor tolerance, temperature drift, and cathode current effects. Total system accuracy requires summing all contributors - ATL431AQDBZR's ≤6mV temperature drift adds ~±0.05% error over –40°C to +125°C, making it suitable for applications needing ±2% overall output tolerance.

Can ATL431AQDBZR replace TL431 in existing designs?

ATL431AQDBZR is pin-compatible with TL431 in SOT-23 (DBZ) package and functions identically in shunt regulator and comparator modes. However, its 35µA I_K(min) enables lower no-load power, and its Q-grade temperature range extends operation beyond TL431's commercial limits. No PCB changes are required, but verify that the reduced minimum cathode current doesn't affect loop stability in high-gain feedback configurations.

What is the purpose of the ANODE pin in ATL431AQDBZR?

The ANODE pin serves as the common reference and return path for both the internal reference circuitry and the Darlington output stage. It must be connected to the local ground or isolated secondary ground - never left floating. All voltage specifications (e.g., V_KA, V_REF) are referenced to ANODE. In flyback designs, connecting ANODE to the secondary-side ground establishes the feedback reference plane, ensuring accurate regulation independent of primary-side noise.