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STMicroelectronics ST13003-K — Logic ICs
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STMicroelectronics ST13003-K NPN Transistor, 400 V, 1.5 A

MPN ST13003-K
End of Life Spot Stock · 24-48h Dispatch 100% Original Sealed

STMicroelectronics ST13003-K NPN bipolar power transistor, 400 V Vce breakdown, 1.5 A collector current, 40 W power dissipation, SOT-32-3 (TO-225AA / TO-126-3) through-hole package, -40°C to 150°C junction temperature.

In Stock: 793 pcs
MOQ: 5 pcs
Logistics: DHL / FedEx DAP (Global Express · 3-7d) Russia & CIS DDP (Door-to-Door Cleared)
Dispatch: Shenzhen / HK
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$0.82 / pc
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1+ pcs
$0.82
10+ pcs
$0.74
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$0.67
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$0.61
500+ pcs
$0.57
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$0.82 / ea · total $4.10

793 in stock — maximum per order · MOQ 5 · 3–4 days lead time

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[SPEC] Essential Parameters Snapshot Full Specifications (11)
Package / Case TO-225AA, TO-126-3
ALT
Facing long factory lead times or allocation on ST13003-K? Verified pin-compatible alternatives available with active Shenzhen stock and 100% solder-ready footprint match.
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Full Technical Specifications

11 Parameters
ST13003-K specifications
Parameter / AttributeSpecification / Value
MountingThrough Hole
FET typeNPN
Voltage - collector emitter breakdown400 V
Current - collector (Ic)1.5 A
Current - collector cutoff1mA
DC current gain (hFE) (Min) @ ic, vce5 @ 1A, 2V
Power - max40 W
Operating temperature-40°C ~ 150°C (TJ)
PackageBulk
CaseTO-225AA, TO-126-3
Vce saturation (Max) @ ib, ic1.5V @ 500mA, 1.5A
100% Footprint Match · Solder-Ready (No PCB Redesign Needed)

Need Stock or a Drop-in Second-Source for ST13003-K?

Package: TO-126 · Pin-compatible replacements with immediate Shenzhen spot stock

Footprint Match 97%
Supply Chain & Allocation Reality:

The 13003 is less a part number than an industry specification: the standard high-voltage NPN for offline SMPS, CFL/LED ballasts and small chargers, made in TO-92, TO-126 and TO-220 by dozens of fabs under prefix variations (MJE / KSE / ST / 3DD). Two things decide whether a substitution works: the 700V figure everyone quotes is the collector-base rating while the sustaining collector-emitter rating is 400V, and self-oscillating ballast circuits depend on the switching speed and gain of the specific grade - not just its voltage.

Verified Pin-Compatible Replacements (4 verified alternatives)

KSE13003 onsemi TO-126
100% Drop-in (Zero Code Change)
Availability & Target Pricing:

Registered Second Source of the Same Spec

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The onsemi-registered version of the 13003 switcher: 400V sustaining / 700V collector-base, 1.5A, 40W class in TO-126, B-C-E lead order.

VCEO(sus) 400V; VCBO 700V; IC 1.5A (3A peak); the standard offline switcher envelope.

Compatibility & Drop-In Notes: A same-spec substitution for any MJE13003 position; storage time and hFE window are specified, which matters for self-oscillating circuits.
Package & Solder Footprint: TO-126 with the collector on the tab, lead order B-C-E - note this is different from the BD139-class E-C-B arrangement.
Shenzhen Warehouse Stock & MOQ: onsemi line stock with full datasheet documentation.
Request Volume Quote for KSE13003 Compare ST13003-K vs KSE13003 Spec Matrix
ST13003 STMicroelectronics TO-126 / TO-220
100% Drop-in (Zero Code Change)
Availability & Target Pricing:

Second-Registered Source

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

STs 13003-equivalent high-voltage NPN in the same ratings envelope; check the specific grade letter for the current and hFE window.

VCEO(sus) 400V; VCBO 700V; 1.5A class in TO-126.

Compatibility & Drop-In Notes: Equivalent to the other registered 13003s; read the grade suffix before bulk substitution - suffixes indicate voltage and gain grades across the family.
Package & Solder Footprint: TO-126 body, collector tab live; insulate against grounded heatsinks.
Shenzhen Warehouse Stock & MOQ: ST stock; Pb-free production lines.
Request Volume Quote for ST13003 Compare ST13003-K vs ST13003 Spec Matrix
MJE13005 onsemi / STMicroelectronics TO-220
Functional Equivalent
Availability & Target Pricing:

The Bigger Brother of the Family

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The higher-current TO-220 member of the 1300x switching family (4A class): same 400V / 700V voltage envelope, more die area for drive and dissipation.

VCEO(sus) 400V; IC 4A class; 75W class with heatsinking - verify the exact grade against its datasheet.

Compatibility & Drop-In Notes: Use when the 13003 fails thermally or the load current is genuinely higher. In self-oscillating ballasts the bigger die has different switching times - re-check the oscillation and base drive rather than assuming it just runs cooler.
Package & Solder Footprint: TO-220 versus TO-126: new mounting, bigger board area, insulator kit.
Shenzhen Warehouse Stock & MOQ: High-volume family stock; among the most counterfeited transistor classes, so lot verification matters.
Request Volume Quote for MJE13005 Compare ST13003-K vs MJE13005 Spec Matrix
MJE13007 onsemi / STMicroelectronics TO-220
Functional Equivalent
Availability & Target Pricing:

Same Family, Higher Power Grades

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

Another upward step in the 1300x ladder (4A / 60-80W class): for power supplies and ballasts that burned through the smaller grades.

VCEO(sus) 400V family envelope; higher current handling than the 13003.

Compatibility & Drop-In Notes: As with the 13005: bigger die, different switching behavior. A blanket swap across a fleet of identical ballasts is fine after one unit is verified; across different designs, verify each.
Package & Solder Footprint: TO-220 mounting and heatsink planning.
Shenzhen Warehouse Stock & MOQ: Deep family stock; sold in matched lots on request.
Request Volume Quote for MJE13007 Compare ST13003-K vs MJE13007 Spec Matrix
Buyer & Quality Checklist for Sourcing Alternatives
  • Read the two voltages correctly: 700V is the collector-base (VCBO) rating; the sustaining collector-emitter rating (VCEO) is 400V. Circuit stress calculations must use the 400V figure.
  • Some CFL/LED ballast designs genuinely require 430V+ sustaining parts. Substituting a marginal 400V grade there is a known cause of repeat failures - check the original grade before ordering a fleet quantity.
  • Package determines pinout in this family: TO-126 parts are B-C-E with the collector on the tab; TO-92 variants (common in CFLs) have their own lead arrangement. Match the package, then check the drawing.
  • In self-oscillating circuits (many CFLs and cheap chargers), base-drive and storage time matter as much as voltage - keep to the same grade family when repairing, do not trade a low-storage-time part for a generic one.
  • The 13003 class is heavily relabeled in the spot market; photograph the lot markings before dispatch and prefer registered second sources (KSE / ST) for fleet repairs.
  • The metal tab is the collector: on live-chassis SMPS, the heatsink is often the negative rail - insulator integrity matters more than usual.
Frequently Asked Technical Questions

Q: Is 13003 a 700V transistor?

A: Partly: 700V is the collector-base (VCBO) rating. The sustaining collector-emitter voltage (VCEO) is 400V, and that is the number that matters for offline switching stress. Designs above ~430V need a higher-grade part.

Q: Can I replace a 13003 with a 13005 or 13007?

A: Electrically yes - same family and pin order, with more current and dissipation (TO-220 body). Mechanically it is a different package. In self-oscillating ballast circuits verify the oscillation and base drive on the first unit, since the bigger die switches differently.

Q: Why do 13003 transistors fail in the same ballast repeatedly?

A: Usually the failure is a symptom: a tired electrolytic (the start-up capacitor), an out-of-spec base resistor, or a design that needed a higher voltage grade in the first place. Replacing the transistor without checking the drive network is a known loop.

Technical Details & Description

400 V NPN for flyback and line-voltage switching

The STMicroelectronics ST13003-K is an NPN bipolar power transistor rated for 400 V collector-emitter breakdown and 1.5 A continuous collector current, housed in a SOT-32-3 (TO-225AA / TO-126-3) through-hole package. It targets low-power flyback converters, auxiliary switch-mode supplies, and line-voltage switching circuits where a single high-voltage transistor handles the primary-side switching.

Vce(sat) is specified at 1.5 V maximum with 500 mA base drive and 1.5 A collector current. The 1 mA maximum collector cutoff current at high temperature is typical for a 400 V part.

Package and mounting — SOT-32-3 through-hole

The ST13003-K comes in a SOT-32-3 through-hole package. It's a three-lead device with the collector connected to the metal tab — the tab is not isolated, so if you bolt it to a heatsink, use an insulating washer or keep the heatsink floating.

Frequently asked questions

What package is ST13003-K?

The ST13003-K is supplied in a SOT-32-3 through-hole package, also referred to as TO-225AA or TO-126-3. The mounting type is through hole, and the package / case is TO-225AA, TO-126-3.

ST13003-K
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