TL431ASA-7 - Diodes Incorporated
Full Technical Specifications
11 Parameters| Parameter / Attribute | Specification / Value |
|---|---|
| Output type | Adjustable |
| Mounting | Surface Mount |
| Reference type | Shunt |
| Voltage - output | 36 V |
| Voltage - output (Min (Fixed)) | 2.495V |
| Output current | 100 mA |
| Current - cathode | 700 µA |
| Operating temperature | -40°C~125°C(TA) |
| Package | Tape & Reel (TR); Cut Tape (CT) |
| Tolerance | ±1% |
| Case | TO-236-3, SC-59, SOT-23-3 |
Need Stock or a Drop-in Second-Source for TL431ASA-7?
Package: SOT-23 / TO-92 / SOT-89 / SOIC-8 · Pin-compatible replacements with immediate Shenzhen spot stock
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)
Licensed Second Source at Commodity Pricing
Shenzhen Spot Stock (24-48h Dispatch)
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.
Direct House Second Source
Shenzhen Spot Stock (24-48h Dispatch)
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.
Modern Low-Current Version Designed to Replace TL431 Sockets
Shenzhen Spot Stock (24-48h Dispatch)
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.
Same Regulator, Mirrored Pinout - Layout Companion
Shenzhen Spot Stock (24-48h Dispatch)
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.
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.