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TL431BCDBZR

Texas Instruments

Texas Instruments TL431BCDBZR, adjustable shunt voltage reference, ±0.5% tolerance, 2.495V min output, 100 mA output, 36V max, SOT-23-3, 0°C to 70°C.

Texas Instruments TL431BCDBZR
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[IN STOCK] In Stock: 2,755 pcs
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MOQ 5 · Tape & Reel (TR); Cut Tape (CT) · RoHS · EIA-481 · DAP/DDP · T/T

[ORIGINAL SEALED] [PRE-SHIP HD PHOTOS] [30D WARRANTY · COC] [TRACKED DAP/DDP]

Technical specifications

TL431BCDBZR specifications
Parameter / AttributeSpecification / Value
Output typeAdjustable
MountingSurface Mount
Reference typeShunt
Voltage - output36 V
Voltage - output (Min (Fixed))2.495V
Output current100 mA
Current - cathode600 µA
Operating temperature0°C~70°C(TA)
PackageTape & Reel (TR); Cut Tape (CT)
Tolerance±0.5%
CaseTO-236-3, SC-59, SOT-23-3
100% Footprint Match · Solder-Ready (No PCB Redesign Needed)

Need Stock or a Drop-in Second-Source for TL431BCDBZR?

Package: SOT-23 / TO-92 / SOT-89 / SOIC-8 · Pin-compatible replacements with immediate Shenzhen spot stock

Footprint Match 98%
Supply Chain & Allocation Reality:

The TL431 sits in the feedback loop of a large share of the flyback supplies ever built - one of the highest-volume analog parts in existence. Genuine supply is never the issue. The issues are three: the tolerance grade (2 percent / 1 percent / 0.5 percent) that decides regulation accuracy, the pinout that differs between TL431 and TL432 and between packages, and the lookalike low-voltage parts (TLV431, LMV431) that are not drop-ins at all. A repair that fits the right part with the wrong orientation simply does not regulate.

Verified Pin-Compatible Replacements (4 verified alternatives)

KA431 onsemi (Fairchild line) SOT-23 / TO-92
100% Drop-in (Zero Code Change)
Availability & Target Pricing:

Licensed Second Source at Commodity Pricing

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

Functionally identical 2.495V shunt regulator from a licensed source; tolerance grades track the same letter system (A = 1 percent, B = 0.5 percent, plain = 2 percent).

Cathode voltage up to 36V; cathode current 1mA to 100mA; reference 2.495V typical.

Compatibility & Drop-In Notes: Match the grade letter when substituting into a regulated rail: a 2 percent grade in place of a 0.5 percent part loosens the output tolerance directly.
Package & Solder Footprint: Verify the pinout against the specific vendor package drawing - the 431 family has multiple pinouts across vendors. In the common SOT-23 the TL431 is pin 1 CATHODE, pin 2 REF, pin 3 ANODE; in TO-92 (at least the TI drawing) it is pin 1 CATHODE, pin 2 ANODE, pin 3 REF.
Shenzhen Warehouse Stock & MOQ: Standard stock; original factory reels and automated production packaging.
Request Volume Quote for KA431 Compare TL431BCDBZR vs KA431 Spec Matrix
LM431 Texas Instruments SOT-23 / TO-92 / SOIC-8
100% Drop-in (Zero Code Change)
Availability & Target Pricing:

Direct House Second Source

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The same 2.495V adjustable shunt regulator under the LM numbering; grades and packages mirror the TL431 line.

Cathode voltage 36V class; cathode current 1mA minimum - the same bias requirement.

Compatibility & Drop-In Notes: Drop-in within the same package and pinout. As always with the 431 family, confirm the package drawing: family pinouts vary by package code, not by brand name alone.
Package & Solder Footprint: Choose the package that matches the original footprint (SOT-23, TO-92, SOIC-8) and confirm pin numbering from the vendor drawing.
Shenzhen Warehouse Stock & MOQ: Branded stock with full documentation; the choice where quality paperwork matters.
Request Volume Quote for LM431 Compare TL431BCDBZR vs LM431 Spec Matrix
ATL431 Texas Instruments SOT-23
Pin-to-Pin (Minor Clock/Init Tuning)
Availability & Target Pricing:

Modern Low-Current Version Designed to Replace TL431 Sockets

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

An improved TL431: same 2.5V-class reference with a far lower minimum cathode current (tens of microamps class versus 1mA), aimed by TI at modernizing existing TL431 designs.

Same 2.5V-class reference; much lower minimum bias current - useful where the original could not regulate at light load.

Compatibility & Drop-In Notes: In most feedback loops it works without component changes. Where the original circuit was designed around the 1mA minimum bias, re-check loop compensation and start-up behavior - the improvement changes those margins.
Package & Solder Footprint: SOT-23 land pattern matches the TL431 DBZ footprint; orientation follows the same K / R / A pin order as the TL431 (not the TL432).
Shenzhen Warehouse Stock & MOQ: Active TI production; the forward-looking replacement for new builds and redesigns.
Request Volume Quote for ATL431 Compare TL431BCDBZR vs ATL431 Spec Matrix
TL432 Texas Instruments / multiple SOT-23 / TO-92
Functional Equivalent
Availability & Target Pricing:

Same Regulator, Mirrored Pinout - Layout Companion

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

Identical die and specifications to the TL431 - the difference is the pinout. In SOT-23: TL432 is pin 1 REF, pin 2 CATHODE, pin 3 ANODE against the TL431 pin 1 CATHODE, pin 2 REF, pin 3 ANODE.

Same 36V cathode ceiling and 1mA minimum cathode current.

Compatibility & Drop-In Notes: Ordered by mistake regularly. It works perfectly - in the wrong orientation it simply will not regulate, which reads as a dead supply on the bench. Treat TL431 and TL432 as different footprint orientations, not interchangeable stock.
Package & Solder Footprint: Before fitting any 431-family part, read the actual marking and the vendor package drawing; the mirrored part fails silently in a TL431 socket.
Shenzhen Warehouse Stock & MOQ: Stocked with an explicit warning label in the drawer - and worth keeping separate from TL431 inventory for exactly this reason.
Request Volume Quote for TL432 Compare TL431BCDBZR vs TL432 Spec Matrix
Buyer & Quality Checklist for Sourcing Alternatives
  • Know both reference pinouts before placing parts: TL431 in SOT-23 (DBZ) is 1 CATHODE / 2 REF / 3 ANODE; the TL431 TO-92 (LP) drawing is 1 CATHODE / 2 ANODE / 3 REF. TL432 swaps cathode and reference in every package.
  • Do not accept TLV431 or LMV431 as a TL431 substitution: the reference voltage is 1.24V instead of 2.495V and the cathode ceiling is a few volts instead of 36V. That is a different regulator for low-voltage rails, not a re-pinned TL431.
  • Match the tolerance grade to the loop: a 2 percent grade on a 12V rail can drift roughly 0.25V; grade A (1 percent) or B (0.5 percent) is what tight supplies were designed around.
  • The TL431 needs at least 1mA of cathode current to regulate. When a repair swaps the surrounding divider or the optocoupler, re-verify that the bias resistor still guarantees that minimum at the lightest load the supply will see.
  • In flyback feedback, the compensation components around the 431 (the RC across REF and cathode) set the loop; substituting the reference without checking them can turn a stable supply into an oscillating one.
Frequently Asked Technical Questions

Q: Is TL432 a drop-in replacement for TL431?

A: No - same function and specifications, different pinout. The SOT-23 TL431 is CATHODE / REF / ANODE on pins 1-2-3; the TL432 is REF / CATHODE / ANODE. It is a layout companion part, not a substitute; in a TL431 socket it will not regulate.

Q: Can I replace TL431 with TLV431?

A: No. The TLV431 has a 1.24V reference and roughly a 6V cathode ceiling versus 2.495V and 36V for the TL431. It is a different regulator for low-voltage rails, not a substitution in a divider-based feedback loop.

Q: Which grade of TL431 do I need?

A: Match the original: standard (2 percent), A (1 percent) or B (0.5 percent). On a 12V output the difference between 2 percent and 0.5 percent is roughly 0.2V of regulation accuracy - enough to matter in chargers and industrial supplies.

Technical details

2.495V shunt reference in a SOT-23-3

Its internal bandgap sets a nominal 2.495 V reference at the cathode, and with two external resistors you program any output up to 36 V. The B-grade ±0.5% tolerance gives tighter regulation than the standard 1% grade — useful when the output accuracy matters more than the BOM cost of the extra resistor divider.

The 100 mA output current is the maximum cathode current the device can sink. In a shunt regulator, that current flows through the bias resistor and the load — if your load pulls more than 100 mA, the reference can't hold regulation and the output droops. The 600 µA minimum cathode current is the floor: below that the device shuts off. It won't survive an engine bay or an outdoor telecom cabinet.

TL431BCDBZR
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