Diodes Incorporated TLV431AFTA

Overview

TLV431AFTA from Diodes Incorporated is a 1.24V adjustable precision shunt regulator in SOT23 package, rated for ±1% initial reference voltage tolerance at +25°C, -40°C to +125°C operating temperature, and 20mA max cathode current. It replaces Zener diodes in feedback loops of isolated DC-DC converters, voltage monitors, and programmable power supplies.

For engineers reviewing the TLV431AFTA datasheet, TLV431AFTA pinout, TLV431AFTA application, or TLV431AFTA equivalent, key selection criteria include reference voltage accuracy over temperature, minimum cathode current (80µA), dynamic output impedance (0.25Ω), and compatibility with optocoupler-based secondary-side regulation in flyback topologies.

Technical Context

The TLV431AFTA operates as a 3-terminal shunt regulator where the REF pin senses voltage via an external resistor divider, and the device sinks cathode current to maintain VREF = 1.24V across the divider. Its internal bandgap reference and error amplifier enable stable regulation without external compensation.

It functions within a cathode-anode voltage range of 1.24V to 18V and requires ≥80µA cathode current for regulation. The device exhibits low temperature drift (11mV over -40°C to +125°C) and high ESD robustness (4kV HBM), making it suitable for industrial and automotive-adjacent power management designs.

Key Specifications

Pinout & Package

TLV431AFTA is housed in a 3-pin SOT23 package (JEDEC TO-236AB). Pin 1 is CATHODE, Pin 2 is ANODE, Pin 3 is REFERENCE. The ANODE must be connected to system ground or lowest potential node; REF pin connects to the center tap of the external voltage divider.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BFTA, TLV431AFTA trades 0.5% accuracy for lower unit cost in non-critical feedback paths; versus TLVH431AFTA, it offers lower VREF and reduced voltage headroom-making it optimal for cost-sensitive 3.3V–15V isolated supplies.

Availability

TLV431AFTA is available at Aetrix Electronics and suitable for isolated DC-DC converters, programmable voltage supervisors, and LDO accuracy enhancement requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for TLV431AFTA 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 semiconductor company specializing in discrete, analog, and mixed-signal devices for power management, signal integrity, and protection applications.

The TLV431 series belongs to Diodes' precision reference and voltage regulation product line, engineered for high-accuracy, low-cost replacement of Zener diodes in feedback, monitoring, and reference circuits across industrial, computing, and consumer power systems.

FAQ

What is the minimum cathode current required for regulation across temperature?

The TLV431AFTA requires ≤80µA minimum cathode current (IKMIN) to maintain regulation over its full -40°C to +125°C operating range. At +25°C, IKMIN is typically 55µA. This value is confirmed in the Electrical Characteristics table under "IKMIN Minimum Cathode Current for Regulation" with test conditions specifying TA = -40°C to +125°C and VKA = VREF.

Can TLV431AFTA replace a standard 3.3V Zener diode directly?

No-it cannot replace a 3.3V Zener directly because it is an adjustable shunt regulator with a fixed 1.24V reference. To regulate at 3.3V, external resistors R1 and R2 must form a voltage divider from the output to REF and ground, setting VOUT = VREF × (1 + R1/R2). This configuration achieves superior accuracy and temperature stability versus a single Zener.

What is the maximum power dissipation in the SOT23 package at +85°C ambient?

At TA = +85°C, the SOT23 package has θJA = 380°C/W. With TJ(max) = +150°C, allowable ΔT = 65°C. Thus, max power = 65°C ÷ 380°C/W ≈ 171mW. This supports up to ~14mA cathode current at 12V VKA (12V × 14mA = 168mW), consistent with the 15mA recommended operating limit in the datasheet.

Does TLV431AFTA require an output capacitor for stability?

No external output capacitor is required for basic shunt regulator stability. The device is internally compensated and remains stable with purely resistive feedback networks. However, a 0.1µF ceramic capacitor from REF to ANODE is recommended in noisy environments to suppress high-frequency coupling, as shown in Figure 1 of the datasheet.