TL431BMFDT - 2.495V Adjustable Shunt Regulator | Nexperia
Артикул: TL431BMFDT ✓ Активен| Кол-во | Цена за ед. | Итого |
|---|---|---|
| 1 | $0.28 | $0,28 |
| 10 | $0.21 | $2,10 |
| 100 | $0.13 | $13,00 |
| 500 | $0.1 | $50,00 |
| 1.000 | $0.08 | $80,00 |
TL431BMFDT Обзор
A shunt regulator, also called a shunt voltage reference, is a two-state device that maintains a constant voltage across its terminals by sinking excess current. Within the power management hierarchy, it sits alongside bandgap references and series regulators as a fundamental building block for voltage monitoring, feedback loops, and precision thresholding. Because it behaves like an error amplifier with an integrated 2.495 V reference, the TL431 family is the de facto standard feedback element in isolated and non-isolated switching power supplies.
Key features include the tight 0.5% initial reference tolerance at 25C, the wide 36 V maximum cathode voltage, and a low dynamic output impedance. The TL431xBM series is qualified for automotive applications, and the device requires only about 1 mA of minimum cathode current for regulation in typical designs, keeping standby losses low.
Technically, the device integrates a 2.495 V bandgap reference, an internal op amp, and an open-collector output transistor. When the voltage at the reference pin exceeds 2.495 V, the cathode conducts and pulls the cathode pin toward the anode, making the part function as a single-supply comparator with a built-in precision reference. Temperature coefficient is approximately 888 ppm/C per third-party parameter listings.
Typical applications include optocoupler feedback in flyback and forward SMPS converters, adjustable voltage monitors and overvoltage crowbar triggers, precision current sources and sinks, and setpoint generation for battery charger circuits.
A key design consideration is stability: with certain cathode-to-reference capacitance ranges the loop can oscillate, so verify the recommended stability region in the Nexperia datasheet and add a compensation capacitor or series resistor if operating near the boundary.
This page synthesizes distributor pricing, drop-in cross-references, and practical design notes not found in the manufacturer datasheet.
Аналоги без доработки для TL431BMFDT — тот же корпус, pin-to-pin совместимость. Компоненты в других корпусах, требующие переработки PCB, исключены.
Варианты в этой серии
Модели той же серии, совместимые без доработки с TL431BMFDT (тот же форм-фактор и посадочное место) — отличается по Operating Temperature Range, Package, Reference Voltage (Vref), Pinning Configuration.
Инструмент быстрого сравнения — выберите альтернативные компоненты для сравнения бок о бок:
TL431BFDT
✅ Прямая замена ⚠️ Характеристики не проверены✓ В наличии
$0.08 / шт.
Открыть даташит →TL431CFDT
✅ Прямая замена ⚠️ Характеристики не проверены📋 Справочный аналог (нет в каталоге)
TL431AFDT
✅ Прямая замена ⚠️ Характеристики не проверены📋 Справочный аналог (нет в каталоге)
TL431AIDBZR
✅ Прямая замена✓ В наличии
$0.08 / шт.
Открыть даташит →LM431CCM3/NOPB
✅ Прямая замена📋 Справочный аналог (нет в каталоге)
KA431
✅ Прямая замена📋 Справочный аналог (нет в каталоге)
AZ431
✅ Прямая замена📋 Справочный аналог (нет в каталоге)
TL431BMFDT Характеристики
| Product Type | Adjustable precision shunt regulator / voltage reference |
| Reference Voltage (Vref) | 2.495 V typical |
| Reference Tolerance at 25C | ±0.5% (B grade) |
| Adjustable Output Voltage Range | 2.495 V to 36 V |
| Maximum Cathode Current | 100 mA |
| Temperature Coefficient | 888 ppm/C |
| Диапазон рабочих температур | -40C to +125C |
| Temperature Grade | Q (automotive, -40C to +125C) |
| Корпус | SOT-23 (TO-236AB), 3-pin |
| Тип монтажа | Surface Mount |
| Pinning Configuration | Normal (Ref / Anode / Cathode) |
| Application Segment | Automotive qualified |
| Топология | Bandgap reference + error amplifier + output transistor |
| Reference Voltage Range (Vref limits) | 2.48 V to 2.55 V |
| Статус RoHS | Compliant |
Конфигурация выводов TL431BMFDT
| Контакт 1 | REF — Reference input - output voltage setpoint sensing (nominal 2.495 V threshold) |
| Контакт 2 | A — Anode - ground / lowest potential terminal |
| Контакт 3 | K — Cathode - regulated output / current sink terminal (up to 100 mA) |
Типичное применение
TL431BMFDT подходит для 6 применениеs: SMPS Optocoupler Feedback, Overvoltage Protection and Crowbar, Precision Current Source, Adjustable Voltage Reference for ADC/DAC Systems, Battery Charger Voltage Regulation, Zener Replacement and Level Shifting.
SMPS Optocoupler Feedback
The TL431BMFDT is the industry-standard error amplifier in isolated flyback and forward converter secondary-side feedback loops. Its 2.495 V reference and 0.5% tolerance set the output voltage setpoint with tight accuracy, while the open-collector output directly drives an optocoupler LED through a resistor, transferring the error signal across the isolation barrier. With the TL431xBM automotive grade rated to 125C, it survives hot secondary-side environments inside sealed adapters and chargers. Compensation (typically a resistor-capacitor network from cathode to reference) stabilizes the loop; the datasheet stability region must be observed to avoid oscillation with certain divider impedances.
Рекомендуется
Overvoltage Protection and Crowbar
Because the TL431BMFDT combines a 2.495 V precision reference with comparator-like behavior, it is ideal for overvoltage detection. A divider scales the monitored rail to the reference pin; when the rail exceeds the threshold, the cathode pulls low and can trigger a thyristor crowbar, drive a fault flag, or gate off a DC-DC converter. The 0.5% reference tolerance gives a predictable trip point, and the 36 V cathode rating allows monitoring of high-voltage buses directly with appropriate dividers. Its automotive -40C to +125C range suits battery-management and automotive rail supervision where transient overvoltage events must be caught reliably.
Рекомендуется
Precision Current Source
The TL431BMFDT forms simple, accurate current sources and current sinks: a sense resistor from anode to reference programs the current as I = 2.495 V / Rsense, with the cathode tied to the supply through a ballast resistor or to a PNP/P-MOSFET pass element. The 0.5% reference accuracy translates directly into current accuracy, outperforming simple zener-based circuits. This topology is common in LED bias, sensor excitation, and 4-20 mA loop transmitters. Power dissipation in the sense resistor and the SOT-23 package must be budgeted, since the device dissipates (Vka x Ika) during regulation.
Рекомендуется
Adjustable Voltage Reference for ADC/DAC Systems
For cost-sensitive data-converter circuits, the TL431BMFDT provides an adjustable precision reference fed from a higher supply rail through a series resistor. Buffering the cathode with an op amp yields a stiff reference for ADC or DAC inputs, while the 0.5% initial tolerance and low dynamic impedance keep setpoint error low. Operating up to 36 V cathode voltage allows referencing from industrial 24 V rails without pre-regulation. For high-resolution converters, add RC filtering to reduce reference noise and consider a dedicated low-noise series reference if noise-free resolution demands exceed what a shunt reference can deliver.
Рекомендуется
Battery Charger Voltage Regulation
In linear and switching battery chargers, the TL431BMFDT senses the battery terminal voltage through a divider and closes the regulation loop, clamping charge voltage at the programmed termination point such as 4.2 V for Li-ion cells. The 2.495 V reference and 0.5% tolerance support accurate termination, which directly affects cell longevity and safety. The automotive-grade temperature range tolerates enclosed charging environments, and the 100 mA cathode capability lets it drive modest gate-drive or status-indication loads directly. Combine with a current-limit element for complete CC/CV charging behavior.
Рекомендуется
Zener Replacement and Level Shifting
As a programmable zener, the TL431BMFDT replaces discrete zener diodes with far better tolerance (0.5% vs typical 5%) and a user-defined clamp voltage from 2.495 V to 36 V set by two resistors. This is valuable for level shifting, supply clamping, and threshold references in industrial I/O modules and sensor interfaces. Unlike a zener, its knee is sharp and its dynamic impedance is low, so regulation is tighter across current variations. The SOT-23 footprint occupies minimal board area, and the automotive qualification permits use in 24 V industrial and vehicle-level signal conditioning chains.
Рекомендуется
Сводка рекомендуемых товаров
Справочные инженерные данные для TL431BMFDT — сравнение, рекомендации по проектированию и информация о соответствии.
Руководство по выбору
Сравнение с аналогами
| Параметр | Этот товар | TL431BFDT | TL431AIDBZR | LM431CCM3/NOPB | KA431 | AZ431 |
|---|---|---|---|---|---|---|
| Package | SOT-23 (TO-236AB) | SOT-23 (TO-236AB) - same | SOT-23 (DBZ) - same footprint | SOT-23 (TO-236AB) - same | SOT-23 - same footprint | SOT-23 - same footprint |
| Brand | Nexperia | Nexperia | Texas Instruments | Texas Instruments | onsemi | Diodes Incorporated |
| Reference Voltage | 2.495 V | 2.495 V | 2.495 V | 2.495 V | 2.495 V | 2.495 V |
| Max Output Voltage | 36 V | 36 V | 36 V | 36 V | 36 V | 36 V |
| Max Cathode Current | 100 mA | 100 mA | 100 mA | 100 mA | 100 mA | 100 mA |
Ключевые отличия
- Tightest tolerance in the FDT family (против TL431BFDT)
- Extended 125C automotive range (против TL431AIDBZR)
- Trade-off: tighter accuracy at potentially higher cost (против AZ431)
Заметки по проектированию
Stability is the most common TL431 design failure. The device can oscillate when the capacitance from cathode to reference falls in a critical range (roughly 0.01 uF to 10 uF depending on cathode current and divider impedance). Consult the Nexperia datasheet stability boundary curves: either keep the cathode-reference capacitance below the lower boundary, add a series resistor with a larger compensation capacitor, or place the compensation network from cathode to reference instead of cathode to anode for wide-bandwidth feedback loops.
Budget power dissipation explicitly: P = (Vka - Va) x Ika. In a 24 V-to-5 V rail monitor with 10 mA cathode current, the device dissipates roughly 190 mW, well within SOT-23 limits, but a 36 V crowbar at 50 mA approaches 1.8 W and will exceed the package. Estimated from the 100 mA / 36 V absolute ratings; verify against the derating curve for your board copper and ambient. Set cathode current above the minimum regulation current (typically about 1 mA) with margin for accuracy.
Keep the resistor divider as close to the REF pin as possible and use 1% or better resistors to preserve the 0.5% reference accuracy. In optocoupler feedback loops, place the TL431 near the optocoupler anode-side resistor to minimize the high-impedance error-node trace length, which is sensitive to switching-noise pickup from the transformer. A small ceramic capacitor across the output at the point of regulation reduces ripple fed into the divider.
Информация о соответствии
RoHS compliant per Nexperia current product status. Automotive temperature class (Q, -40C to +125C) per Nexperia product overview. REACH/halogen-free status not stated in retrieved data - consult Nexperia material declarations.
