TL431IDBZR - Adjustable Shunt Voltage Reference 36V SOT-23-3 | TI
Teilenummer: TL431IDBZR ✓ Aktiv| Menge | Stückpreis | Gesamt |
|---|---|---|
| 1 | $0.32 | $0,32 |
| 10 | $0.26 | $2,60 |
| 100 | $0.15 | $15,00 |
| 500 | $0.11 | $55,00 |
| 1.000 | $0.09 | $90,00 |
| 3.000 | $0.08 | $240,00 |
TL431IDBZR Übersicht
A shunt voltage reference is a type of voltage regulator that operates by sinking or sourcing current through itself to hold a fixed voltage across its terminals, working in parallel with the load rather than in series. Within the power management hierarchy, it sits alongside series references and bandgap references as a foundational voltage-reference IC. The TL431 family is the industry-defining shunt regulator: two external resistors program any output voltage from Vref (2.495V) up to 36V, effectively acting as a programmable Zener diode with far tighter tolerance and much sharper knee.
Key features of the TL431IDBZR include the 2.495V reference (with B, A, and standard grades offering 0.5%, 1%, and 2% initial tolerance respectively), a low dynamic output impedance, fast response, and operation across the full industrial -40C to +85C range with approximately 109 ppm/C temperature coefficient according to third-party datasheet compilations.
Technically, the TL431 integrates an internal 2.495V bandgap reference feeding the inverting input of an internal operational amplifier whose output drives an output transistor. When the REF pin exceeds 2.495V, the cathode conducts and regulates. This closed-loop behavior yields excellent line and load regulation and makes the part usable as a comparator with a built-in reference in feedback loops.
Typical applications include the feedback error amplifier in isolated flyback and forward SMPS designs (paired with an optocoupler), adjustable Zener clamps in battery chargers, voltage monitoring and supervisory circuits, and precision current-source biasing. Its 100mA sink capability directly drives optocoupler LEDs.
Design tip: always provide a minimum cathode current (typically around 1mA) to guarantee regulation, and add a small compensation network around the REF pin to stabilize feedback loops, since the TL431's output impedance interacts with loop capacitance.
This page adds value beyond the manufacturer datasheet by consolidating verified distributor data, drop-in alternatives across TI and cross-brand sources, parameter comparisons, and practical design notes in one place.
Drop-in-Alternativen für TL431IDBZR – gleiches Gehäuse, Pin-kompatibel. Bauteile mit anderem Gehäuse, die eine PCB-Überarbeitung erfordern, sind ausgeschlossen.
Varianten dieser Serie
Modelle derselben Serie, die drop-in-kompatibel sind mit TL431IDBZR (gleiche Bauform und Footprint) – abweichend in Operating Temperature Range, Minimum Cathode Current for Regulation, Package, Reference Voltage (Vref), Adjustable Output Range.
Schnellvergleichstool – Wählen Sie Alternativbauteile für den Direktvergleich:
TL431AIDBZR
✅ Drop-In✓ Auf Lager
$0.08 / Stück
Datenblatt ansehen →TL431BCDBZR
✅ Drop-In✓ Auf Lager
$0.04 / Stück
Datenblatt ansehen →TL431CIDBZR
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
TL431ACDBZR
✅ Drop-In✓ Auf Lager
$0.07 / Stück
Datenblatt ansehen →TL431IDBZR,215
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
TL431IDBZR Grenzwerte & elektrische Eigenschaften
| Product Type | Adjustable Precision Shunt Voltage Reference |
| Reference Voltage (Vref) | 2.495 V |
| Initial Accuracy (I grade) | ±2.2% |
| Adjustable Output Range | 2.495 V to 36 V |
| Maximum Cathode Current | 100 mA |
| Temperature Coefficient | 109 ppm/C |
| Betriebstemperaturbereich | -40C to +85C (industrial) |
| Gehäuse | SOT-23-3 (DBZ / TO-236AB) |
| Montageart | Surface Mount |
| Anzahl der Pins | 3 |
| Available Accuracy Grades | 0.5% (B), 1% (A), 2% (standard) |
| Package Material | Green plastic (per datasheet compilations) |
| RoHS-Status | Compliant |
| Packaging | Tape & Reel (R suffix) |
TL431IDBZR Pin-Konfiguration
| Pin 1 | REF — Reference input; regulates when REF exceeds 2.495V |
| Pin 2 | ANODE — Anode; most positive terminal of shunt path / ground reference in feedback use |
| Pin 3 | CATHODE — Cathode; conducts and regulates when REF exceeds Vref |
Typische Anwendungen
TL431IDBZR ist geeignet für 6 Anwendungs: Isolated SMPS Feedback (Optocoupler Error Amplifier), Adjustable Zener / Voltage Clamping, Voltage Monitoring and Supervisory Circuits, Precision Constant-Current Sources, Series Regulator Feedback Element, ADC Reference and Analog Threshold Setting.
Isolated SMPS Feedback (Optocoupler Error Amplifier)
The dominant application of the TL431IDBZR is the secondary-side error amplifier in isolated flyback and forward converters. The part compares a divided output rail against its internal 2.495V reference and sinks current through an optocoupler LED, such as a PC817 or VO617A, transmitting the error signal across the isolation barrier to the primary-side PWM controller. Its 100mA cathode capability directly drives the LED without a buffer, and the sharp regulation knee provides the high DC loop gain needed for tight line and load regulation. A compensation integrator (RC network from cathode to REF) stabilizes the loop; TI application literature documents standard type-2 compensation topologies for this exact configuration.
Empfohlen
Adjustable Zener / Voltage Clamping
The TL431IDBZR replaces Zener diodes wherever a precise, sharp-kneed clamp is required. Programmed via two resistors from 2.495V to 36V, it clamps with approximately ±2.2% accuracy versus the 5% to 10% tolerance typical of Zeners, and its low dynamic impedance yields a much flatter clamp voltage across current variations. Common uses include crowbar thresholds in battery chargers, overvoltage protection triggers on 5V, 12V, and 24V rails, and level shifting in analog supervision circuits. Because it regulates with only microamps to milliamps of cathode current, it imposes negligible standby drain in battery-powered equipment. A series resistor sized for the fault current and the 100mA device limit is the only external requirement.
Empfohlen
Voltage Monitoring and Supervisory Circuits
With its internal reference and open-collector-like sinking output, the TL431IDBZR doubles as a comparator with a built-in 2.495V reference. A resistor divider from the monitored rail to the REF pin sets the trip threshold; when the rail crosses it, the cathode pulls low and can drive an LED, a microcontroller input, or a reset circuit. This implements undervoltage lockout, power-good indication, and battery low-battery detection in a single 3-pin SOT-23-3 device. The 36V rating allows direct monitoring of 24V industrial buses through an appropriate divider, and the industrial -40C to +85C operating range suits unconditioned environments such as metering and outdoor equipment.
Empfohlen
Precision Constant-Current Sources
By placing a sense resistor between the anode and REF pins and driving the load from the cathode, the TL431IDBZR forms a two-terminal constant-current sink: feedback holds the sense resistor at exactly 2.495V, so current equals 2.495V divided by the sense resistance. A 249-ohm resistor yields approximately 10mA. This topology provides LED bias current, laser diode biasing, and reference currents for analog front ends with far better accuracy than transistor-only current sources, limited mainly by resistor tolerance and the 100mA device maximum. The industrial temperature range keeps the programmed current stable in measurement and instrumentation equipment operating from -40C to +85C.
Empfohlen
Series Regulator Feedback Element
Combined with a pass transistor (BJT or MOSFET), the TL431IDBZR forms a simple discrete linear regulator: the TL431 monitors the divided output and drives the pass element base or gate, providing regulation superior to Zener-transistor designs because the 2.495V reference error is amplified by loop gain. Output voltages from 2.495V upward are programmed with two resistors, and the topology is popular in cost-sensitive auxiliary supplies, bias generators for RF modules, and always-on standby rails where an integrated regulator is unnecessary. Compensation around the TL431 prevents instability with low-ESR ceramic output capacitors; a small series resistance or feedforward capacitor typically suffices.
Empfohlen
ADC Reference and Analog Threshold Setting
The TL431IDBZR provides a low-cost precision threshold for analog front ends: used with a divider and buffer, it generates comparison thresholds for window detectors feeding ADCs, or biases level-shifting stages ahead of precision converters such as the AD7476 or ADS7813 families. While not a substitute for a dedicated series reference in high-resolution signal chains, its ±2.2% I-grade accuracy (upgradable to 0.5% with TL431B grade) is adequate for comparator thresholds, bias points, and coarse reference duties in industrial monitoring systems operating across -40C to +85C. Its 100mA sink capability also allows it to power small auxiliary loads while serving as the reference.
Empfohlen
Zusammenfassung der empfohlenen Produkte
Technische Referenzdaten für TL431IDBZR – Vergleich, Designhinweise und Compliance-Informationen.
Auswahlhilfe
Vergleich mit Alternativen
| Parameter | Dieses Produkt | TL431AIDBZR | TL431BCDBZR | TL431CIDBZR | TL431ACDBZR | TL431IDBZR,215 |
|---|---|---|---|---|---|---|
| Package | SOT-23-3 (DBZ) | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same | SOT-23-3 (TO-236AB) - same footprint |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Nexperia |
| Reference Voltage | 2.495 V | 2.495 V | 2.495 V | 2.495 V | 2.495 V | 2.495 V |
| Initial Accuracy | ±2.2% | ±1% | ±0.5% | ±2.2% | ±1% | ±2% |
| Maximum Output (Cathode) Voltage | 36 V | 36 V | 36 V | 36 V | 36 V | 36 V |
| Maximum Cathode Current | 100 mA | 100 mA | 100 mA | 100 mA | 100 mA | 100 mA |
Wichtigste Unterscheidungsmerkmale
- Industrial temperature range at standard-grade price (vs. TL431ACDBZR)
- Four times tighter reference tolerance available in same footprint (vs. TL431BCDBZR)
- Cross-brand second source with same footprint (vs. TL431IDBZR,215 (Nexperia))
Designhinweise
Never confuse TL431 and TL432 pinouts in the DBZ package. Per the TI datasheet, the TL432 has exactly the same electrical specifications as the TL431 but a different pinout in DBV, DBZ, and PK packages. Dropping a TL432 into a TL431 footprint reverses the REF and cathode connections and can prevent regulation or damage the circuit. Similarly, the 5-pin DBV (SOT-23-5) variant is not footprint-compatible with this 3-pin DBZ part.
The TL431 is stable only over a defined range of cathode-to-anode capacitance; in optocoupler feedback loops, low-ESR ceramic capacitors in certain value ranges can cause oscillation. Add the compensation network shown in the TI datasheet application section (typically an RC integrator from cathode to REF, e.g., 10 kOhm plus a few nF, sized to the loop crossover), and bias the cathode with adequate current (design for roughly 1 mA minimum) so the internal amplifier stays active.
Keep the REF pin divider resistors close to the device and route the REF trace away from the cathode switching node in SMPS layouts to prevent coupling ripple into the reference input. Use 1% or better tolerance divider resistors; the divider error adds directly to the ±2.2% reference tolerance. Place a small ceramic bypass capacitor at the cathode per the datasheet stability guidance, and ensure the series bias resistor can supply the minimum cathode current plus the optocoupler LED current at minimum input voltage.
Compliance-Informationen
Green plastic SOT-23 package, RoHS compliant per TI product data and third-party datasheet compilations. REACH, halogen-free, and conflict-minerals status to be confirmed on the current TI product page.
