Texas Instruments TLV431BCDBZR

Overview

TLV431BCDBZR from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, ±0.5% initial tolerance at 25°C, 0.25 Ω typical dynamic impedance, and operation down to 1.24 V cathode-anode voltage - used as an integrated reference in isolated flyback secondary-side regulation, Zener replacement, and voltage monitoring circuits.

For engineers reviewing the TLV431BCDBZR datasheet, TLV431BCDBZR pinout, TLV431BCDBZR application, or TLV431BCDBZR equivalent, this page delivers verified electrical specs, SC-70 package details, functional mode distinctions (open-loop comparator vs closed-loop shunt regulator), thermal performance data, and real-world design implications for 3.3 V SMPS feedback loops and low-voltage sensing.

Technical Context

The TLV431BCDBZR implements a bandgap-referenced error amplifier with Darlington output stage, enabling precise shunt regulation from 1.24 V to 6 V via two external resistors. Its internal reference is trimmed to 0.5% accuracy at 25°C and exhibits 4 mV max drift over 0°C to 70°C (TLV431BC grade).

It operates in two distinct functional modes: open-loop comparator mode (with integrated 1.24 V reference) requiring ≥55 µA cathode current for full gain, and closed-loop shunt regulator mode where feedback from cathode to reference pin forces regulation - both modes stable without output capacitance due to internal compensation.

Key Specifications

Pinout & Package

TLV431BCDBZR is housed in an ultra-small SC-70 (DCK) package measuring 2.0 mm × 1.5 mm - 40% smaller footprint than SOT-23-3 - with 6 pins, of which only three are functional (CATHODE, REF, ANODE); pins 4 and 5 are NC, and pin 2 connects to substrate (must tie to ANODE or leave open).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431ACDBZR, TLV431BCDBZR offers tighter reference accuracy for precision feedback loops; compared with TLVH431ACDBVR, it provides superior low-voltage performance and smaller footprint but sacrifices voltage headroom and current capacity - selection depends on whether accuracy, size, or voltage range dominates the design constraint.

Availability

TLV431BCDBZR is available at Aetrix Electronics and suitable for isolated flyback power supplies, voltage monitoring circuits, Zener replacement designs, and programmable current sinks requiring stable component supply and guaranteed long-term manufacturability.

Supply support for TLV431BCDBZR 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 delivering analog and embedded processing solutions, with leadership in precision analog, power management, and signal chain technologies.

The TLV431 family was designed specifically for low-voltage, high-accuracy shunt regulation in space-constrained power management and sensing applications - targeting 3.3 V and lower systems where legacy TL431 devices cannot operate.

FAQ

What is the reference voltage tolerance of TLV431BCDBZR at 25°C?

The TLV431BCDBZR has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 1.24 V nominal value with min/max bounds of 1.234 V and 1.246 V. This grade (B) is confirmed in Section 5.7 of the TI datasheet SLVS139Z and applies specifically to the TLV431BC variant in SC-70 packaging. The tolerance remains stable across the 0°C to 70°C operating range with ≤4 mV total drift.

Can TLV431BCDBZR replace a standard Zener diode in a 3.3 V regulator?

Yes, TLV431BCDBZR can directly replace a Zener diode in 3.3 V applications - it regulates from 1.24 V to 6 V using two external resistors, offers ±0.5% initial accuracy (vs ±5% for typical Zeners), and provides 0.25 Ω dynamic impedance for superior load regulation. Unlike Zeners, TLV431BCDBZR requires only 55–100 µA minimum cathode current and integrates its own reference, eliminating external components.

What is the correct way to connect the substrate pin (Pin 2) on TLV431BCDBZR?

Pin 2 on TLV431BCDBZR is the substrate connection and must be either tied directly to the ANODE (Pin 6) or left electrically floating - it must never be connected to ground or any other potential. This requirement is explicitly stated in Table 4-1 and Figure 4-5 of the TI datasheet. Incorrect connection risks latch-up or parametric shift, especially under transient conditions.

Does TLV431BCDBZR require an output capacitor for stability?

No, TLV431BCDBZR does not require an output capacitor for stability because it is internally compensated - a key feature distinguishing it from many op-amp-based references. As confirmed in Section 7.3, the device remains stable in both open-loop comparator and closed-loop shunt regulator configurations without external capacitance. However, if added, capacitive load must be selected per Figure 5-19–5-21 to avoid phase-margin degradation.

What are the absolute maximum ratings for cathode voltage and current on TLV431BCDBZR?

The absolute maximum cathode voltage (V_KA) for TLV431BCDBZR is 7 V, and the continuous cathode current (I_K) is ±20 mA - both specified in Section 5.1 of the TI datasheet SLVS139Z. Exceeding these limits may cause permanent damage. For reliable operation, the recommended cathode voltage is 1.24 V to 6 V, and cathode current should stay within 0.1 mA to 15 mA per Section 5.3.