The TO-264 is the largest standard through-hole power package in the JEDEC transistor-outline family. Registered as SOT-199 and designated TO-264AA in JEDEC Publication 95, it houses IGBTs, power MOSFETs, and bipolar transistors that demand die sizes and current ratings beyond what the TO-247 can accommodate. With a plastic body measuring approximately 26 mm × 20 mm and a mounting-hole tab designed for direct bolting to an external heatsink, the TO-264 package targets applications from 200 W to beyond 500 W at case temperature. This reference provides the verified dimensions, thermal performance data, and a head-to-head comparison with TO-247 and TO-220 that the existing literature omits.
Key Takeaways
• TO-264 body dimensions are approximately 26.0 mm long × 20.2 mm wide × 5.0 mm thick, with a 5.45 mm lead pitch (3-lead variant).
• The package uses a screw-through metal tab for heatsink mounting, unlike the clip-only TO-247PLUS.
• Typical junction-to-case thermal resistance (RθJC) ranges from 0.37 to 0.70 °C/W, enabling 200–300 W dissipation at TC = 25 °C with appropriate heatsinking.
• Key devices: onsemi MJL21194 (NPN, 250 V, 16 A, 200 W), Microchip APT10026L2LL (1000 V N-MOSFET, 38 A, 260 mΩ).
• Thermal insulator pads for TO-264 measure 28 × 22 mm (alumina) or 29 × 22 mm (mica), per Innovacera and Wakefield-Vette specifications.
What Is the TO-264 Package?
The TO-264 is a plastic-molded, through-hole power semiconductor package standardized by JEDEC under Publication 95. It houses power transistors, thyristors, and low-pin-count ICs with 2 to 5 leads. The large metal mounting tab contains a screw hole for bolting directly to an external heatsink, giving the TO-264 superior thermal conductivity compared to smaller TO outlines. Synonyms include SOT-199, TO-264AA (3-lead), and TO-3PL in some vendor catalogs. The package was developed to bridge the gap between the TO-247 (which handles up to roughly 150–200 W) and discrete power modules, serving applications such as motor drives, audio power amplifiers, welding inverters, and industrial power supplies.
[IMAGE 1: Annotated TO-264 package outline drawing with JEDEC dimension callouts | alt: “TO-264 package outline dimensions with JEDEC symbols”]
TO-264 Package Outline Dimensions
The table below lists the TO-264AA (3-lead) outline dimensions compiled from the onsemi MJL21193/MJL21194 datasheet package drawing and the eesemi.com reference. Controlling dimension is millimeters.
| Parameter | Symbol | Typ/Min (mm) | Max (mm) | Notes |
| Overall height (seated) | A | 4.70 | 5.30 | Body only, excl. leads |
| Body length | D | 25.40 | 26.67 | Tab to lead tip |
| Body width | E | 19.60 | 20.32 | Across mold body |
| Body thickness | Q | 4.83 | 5.33 | — |
| Lead pitch | e | 5.45 BSC | — | 3-lead variant |
| Lead width | b | 1.14 | 1.40 | — |
| Lead thickness | c | 0.64 | 0.89 | — |
| Lead length (below seating) | L | 17.53 | 20.32 | Formed leads |
| Tab hole diameter | — | 3.51 | 3.73 | M3 screw clearance |
| Tab thickness | — | 1.14 | 1.52 | Copper alloy |
| Mounting-hole center to body edge | — | ≈7.5 | — | Allows M3 screw + washer |
Source: onsemi MJL21193/MJL21194 datasheet (MJL21193-D.PDF); eesemi.com TO-264 reference; RS Components MJL21196G listing (height 37.8 mm overall including leads, width 5.3 mm lead span, length 20.3 mm body).
The Infineon TO-247PLUS application note (AN2017-01) confirms the TO-264 plastic body as 20.20 mm × 26.00 mm. The screw hole in the tab reduces the useful die-attach area to roughly the same as a TO-247PLUS (~190 mm²), despite the larger overall footprint.
TO-264 vs TO-247 vs TO-220: Package Comparison
Selecting between high-power through-hole packages comes down to die size, thermal budget, and mechanical assembly. The table below summarizes the key parameters.
| Parameter | TO-220AB | TO-247AC | TO-247PLUS 3pin | TO-264AA |
| Body length (mm) | ~15.9 | ~20.8 | ~21.0 | ~26.0 |
| Body width (mm) | ~10.2 | ~15.9 | ~15.8 | ~20.2 |
| Lead pitch (mm) | 2.54 | 5.45 | 5.45 | 5.45 |
| Lead count | 3 | 3 | 3 | 3 (2–5 variants) |
| Mounting hole | Yes | Yes | No (clip mount) | Yes |
| Thermal pad area (mm²) | ~70 | ~140 | ~190 | ~190 (net of hole) |
| Typical RθJC (°C/W) | 1.0–4.0 | 0.3–1.0 | 0.2–0.8 | 0.37–0.70 |
| Max PD at TC=25°C (W) | 50–100 | 150–300 | 200–400 | 200–500 |
| Typical max ID or IC (A) | ≤75 | ≤150 | ≤160 | ≤80 (BJT), ≤38 (HV-MOS) |
| Insulator pad size (mm) | 20×14 | 22×17 | 22×17 (compatible) | 28×22 |
Sources: Infineon AN2017-01 for TO-247PLUS dimensions and pad area; onsemi MJL21194 datasheet for TO-264 RθJC (0.70 °C/W) and PD (200 W); Microchip APT10026L2LL datasheet for HV-MOSFET specs; Innovacera for insulator pad sizing.
[IMAGE 2: Side-by-side comparison of TO-220, TO-247, and TO-264 packages at the same scale | alt: “TO-220 vs TO-247 vs TO-264 package size comparison”]
Thermal Performance and Heatsink Assembly
Junction-to-case thermal resistance: The TO-264’s large copper tab delivers RθJC values typically between 0.37 and 0.70 °C/W for power BJTs (per the onsemi MJL21194 datasheet, RθJC = 0.70 °C/W for the 200 W device). High-voltage MOSFETs in TO-264 from Microchip’s APT family achieve RθJC as low as 0.37 °C/W. For comparison, a TO-247 device typically sits at 0.3–1.0 °C/W, and a TO-220 at 1.0–4.0 °C/W.
Mounting: The tab’s 3.5–3.7 mm hole accepts an M3 screw. Recommended torque is 0.5–0.8 N·m for steel screws into aluminum heatsinks, per Infineon assembly guidelines. Over-torquing risks cracking the epoxy body or deforming the leadframe.
Thermal interface materials: Alumina (Al₂O₃) ceramic pads for TO-264 are 28 × 22 × 1 mm (Innovacera specification). Mica insulators measure 29 × 22 mm. Silicone-based sil-pads are harder to source in TO-264 size; the Wakefield-Vette CD-02-05-264 (26.7 × 21.6 mm, single-hole) is one of the few stocked options. When electrical isolation is not needed, thermal grease applied at 20–50 µm thickness gives the lowest RθCS.
Worked example: An MJL21194 (RθJC = 0.70 °C/W, TJ(max) = 150 °C) mounted on a heatsink with RθSA = 1.5 °C/W using a mica insulator (RθCS ≈ 0.5 °C/W) at TA = 50 °C can dissipate PD = (150 − 50) / (0.70 + 0.50 + 1.50) = 100 / 2.70 ≈ 37 W continuously. That covers a comfortable margin for a 100 W per-channel Class AB amplifier output stage.
Common Devices in the TO-264 Package
The TO-264 serves two primary constituencies: high-power audio and industrial power conversion.
Audio power BJTs (onsemi MJL series): The MJL21193 (PNP) and MJL21194 (NPN) are the definitive complementary pair for high-end audio output stages. Both are rated 250 V, 16 A, 200 W with Perforated Emitter technology for low distortion. The MJL3281A (NPN, 260 V, 15 A, 200 W) and MJL1302A (PNP) are similar alternatives. All use TO-264-3 (TO-264AA).
High-voltage MOSFETs (Microchip APT series): The APT10026L2LL is a 1000 V, 38 A N-channel Power MOS 7 device with 260 mΩ RDS(on) at VGS = 10 V, housed in the TO-264 MAX package. The APT10050LVFRG (1000 V, 21 A) is another Microchip device in TO-264(L).
IGBTs: Infineon’s TRENCHSTOP 5 family and onsemi’s FGL series include TO-264 options for 600–1200 V, 40–80 A ratings, aimed at motor drives and welding equipment.
Rectifiers: MCC Semi’s GP12022 is a 2200 V, 120 A standard-recovery rectifier in a 2-pin TO-264P package, designed for industrial power conversion.
[IMAGE 3: Photograph of MJL21194 and APT10026L2LL side by side in TO-264 package | alt: “onsemi MJL21194 and Microchip APT10026L2LL in TO-264 packages”]
Frequently Asked Questions
What is the difference between TO-264 and TO-247?
The TO-264 body is approximately 26 × 20 mm, while TO-247 measures roughly 21 × 16 mm. TO-264 has a screw hole in the mounting tab; standard TO-247 does as well, but the newer TO-247PLUS omits it. The TO-264 accommodates a physically larger die and higher power dissipation ratings, but at the cost of a significantly larger heatsink footprint. Lead pitch is the same at 5.45 mm.
Is TO-264 the same as TO-3PL?
Some manufacturers, particularly in Asian supply chains, label the TO-264 as TO-3PL (TO-3 Plastic Long). They are functionally the same package with the same dimensions and mounting hole. JEDEC’s official designation is TO-264AA (3-lead). Always verify by cross-referencing the outline drawing in the device datasheet.
What heatsink fits a TO-264?
Any heatsink designed for TO-247 mounting will physically accept a TO-264, since the screw-hole pitch is compatible. However, the TO-264 body is wider, so verify that the heatsink’s flat mounting area accommodates at least 22 mm of width. Arcol Ohmite’s PA-T22-38E (3.13 °C/W, 55 × 32 × 39 mm) and C40-058-AE are designed explicitly for TO-264.
Why choose TO-264 over a power module?
The TO-264 is a discrete, single-device package. It costs a fraction of a power module and allows individual device selection, paralleling, and replacement. For audio amplifiers and single-switch converters under 500 W, TO-264 offers a better cost-to-performance ratio than modular alternatives. Above 500 W or in multi-phase topologies, power modules with integrated gate drivers and optimized layouts usually win.
When to Specify the TO-264
Specify the TO-264 when your design exceeds the thermal or die-size limits of TO-247 and you need a through-hole, screw-mounted solution that bolts to a conventional extruded heatsink. It is the standard choice for complementary BJT output stages in high-fidelity amplifiers (onsemi MJL series) and for single high-voltage MOSFETs in switch-mode converters above 500 V.
Move down to TO-247 when board density matters and 150–200 W is sufficient. Move up to a power module when current exceeds 80 A or when half-bridge integration simplifies gate-drive layout. If you are designing to Infineon’s ecosystem and want TO-264-class performance in a smaller footprint without a screw, evaluate the TO-247PLUS, which achieves roughly the same net die-attach area (~190 mm²) in a body 30% smaller.
