Texas Instruments TLV431CLP

Overview

TLV431CLP from Texas Instruments is a low-voltage adjustable precision shunt regulator in TO-92 (LP) package, delivering 1.24 V reference voltage with ±1.5% initial tolerance at 25°C, 0.25 Ω typical dynamic impedance, and operation down to 1.24 V cathode-anode voltage - used for secondary-side regulation in isolated 3.3 V flyback SMPSs and as a Zener diode replacement in on-board voltage monitoring circuits.

For engineers reviewing the TLV431CLP datasheet, TLV431CLP pinout, TLV431CLP application, or TLV431CLP equivalent, key selection considerations include its 1.24 V reference accuracy over temperature (±11 mV from –40°C to 125°C), ultra-low 80 µA minimum cathode current requirement, TO-92 thermal resistance (140°C/W), and compatibility with resistive feedback networks for output voltages from 1.24 V to 6 V.

Technical Context

The TLV431CLP implements a bandgap-referenced error amplifier with Darlington sink output stage, enabling precise closed-loop shunt regulation or open-loop comparator operation with integrated 1.24 V reference. Its internal architecture requires ≥80 µA cathode current to maintain linear regulation and supports stable operation without external compensation capacitors.

It operates across three temperature grades: TLV431C (0°C to 70°C), TLV431I (–40°C to 85°C), and TLV431Q (–40°C to 125°C); the 'C' suffix in TLV431CLP confirms commercial-grade specification with 1.24 V ±1.5% reference tolerance and 4 mV max reference drift over 0°C–70°C.

Key Specifications

Pinout & Package

TLV431CLP uses the TO-92 (LP) 3-pin through-hole package with standard lead configuration: Pin 1 = Anode (common ground node), Pin 2 = Cathode (shunt current input/output), Pin 3 = Reference (feedback input). The anode must be connected to system ground or common return path; cathode connects to regulated rail or optocoupler LED anode; reference connects to voltage divider midpoint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431CLP, TLV431AILP offers improved accuracy for precision feedback loops but shares identical thermal performance and layout compatibility, whereas TL431ACLP provides superior initial tolerance but sacrifices low-voltage operation and increases minimum bias current by 12.5×.

Availability

TLV431CLP is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, and consumer appliance control boards requiring stable component supply with full temperature-grade traceability and long-lifecycle support.

Supply support for TLV431CLP 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 specializing in analog and embedded processing technologies, with leadership in precision analog ICs and power management solutions.

The TLV431 family was designed specifically for low-voltage, low-power shunt regulation in isolated DC/DC converters and precision voltage monitoring - targeting cost-sensitive, space-constrained applications where TL431 cannot operate.

FAQ

What is the reference voltage tolerance of TLV431CLP at 25°C?

The TLV431CLP has a reference voltage tolerance of ±1.5% at 25°C, meaning its V_REF falls within 1.222 V to 1.258 V under nominal conditions. This tolerance is specified per the 'C' grade (0°C to 70°C operating range) and applies to the TLV431 variant without A or B suffix. The TLV431CLP datasheet confirms this value in Section 5.5 Electrical Characteristics.

Can TLV431CLP regulate output voltages below 1.24 V?

No, TLV431CLP cannot regulate below its internal reference voltage of 1.24 V. Its minimum output voltage equals V_REF, and the adjustable range extends only upward to 6 V via external resistors. Attempting to force cathode voltage below 1.24 V places the device outside regulation, resulting in uncontrolled leakage current. This behavior is documented in the TLV431CLP functional description and Figure 5-4.

What is the minimum cathode current required for TLV431CLP to maintain regulation?

The TLV431CLP requires a minimum cathode current of 80 µA typical (up to 100 µA over temperature) to sustain regulation. Below this threshold, the internal amplifier exits linear operation, causing loss of feedback control and increased output impedance. This parameter is verified in Section 5.5 under IK(min) and aligns with the TLV431C grade specifications in the TLV431CLP datasheet.

Is TLV431CLP pin-compatible with TL431 in TO-92 package?

Yes, TLV431CLP is pin-compatible with TL431ACLP and TL431BCLP in the TO-92 (LP) package: Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Reference. However, direct substitution requires verifying that the 1.24 V reference and lower minimum cathode current (80 µA vs 1 mA) do not destabilize existing compensation networks designed for TL431's higher gain and voltage threshold.

Does TLV431CLP require an external output capacitor for stability?

No, TLV431CLP is internally compensated and remains stable without an external output capacitor between cathode and anode. This is confirmed in Section 7.3 Feature Description and Figure 5-19–5-21 stability analysis. Adding capacitance may introduce phase margin degradation depending on value and layout; TI recommends consulting the stability boundary curves before adding >1 nF.