# TO package (through-hole)

A through-hole transistor, regulator or diode package standing on the board, built from the maker's package drawing. These are the JEDEC outlines that every maker builds:

| `package` | Leads | Body (W x thickness x height) | Source |
|---|---|---|---|
| `TO-220AB` | 3, 2.54 pitch | 10.16 x 4.45 x 15.09 (tab included) | Vishay Siliconix 92506 |
| `TO-220AC` | 2, 5.08 apart | 10.31 x 4.45 x 15.05 (tab included) | Vishay Semiconductors 95221 |
| `TO-220F` | 3, 2.54 pitch | 10.17 x 4.66 x 15.53, fully moulded | Central Semiconductor TO-220FP |
| `TO-220F-2` | 2, 5.10 apart | 10.31 x 4.80 x 15.10, fully moulded | Central Semiconductor TO-220FP-2 |
| `TO-262` | 3, 2.54 pitch | 10.16 x 4.45 x 10.67 (tab included) | Vishay Siliconix 91367 |
| `TO-251AA` | 3, 2.29 pitch | 6.54 x 2.29 x 7.18 (tab included) | Vishay Siliconix 91362 |
| `TO-247AC` | 3, 5.46 pitch | 15.70 x 5.02 x 20.55 | Vishay Siliconix 91360 |
| `TO-126` | 3, 2.25 pitch | 7.95 x 2.60 x 11.25 | Central Semiconductor TO-126 |
| `TO-92` | 3 straight, 1.27 pitch | 4.83 x 3.68 x 4.83 | TI LP0003A |
| `TO-3` | 2, 10.93 apart | flange 39.23 x 25.84 with 2 holes 30.15 apart, can Ø 20.62, 8.89 high | Central Semiconductor TO-3 |
| `TO-18` | 3, on a Ø 2.54 circle | flange Ø 5.58, can Ø 4.74, 4.83 high | Central Semiconductor TO-18 |
| `TO-18-2` | 2, 2.54 apart | as `TO-18` | Central Semiconductor TO-18 2-Lead |
| `TO-39` | 3, on a Ø 5.08 circle | flange Ø 8.96, can Ø 8.26, 6.35 high | Central Semiconductor TO-39 |
| `TO-46` | 3, on a Ø 2.54 circle | flange Ø 5.58, can Ø 4.74, 1.91 high | Central Semiconductor TO-46 |

Lead 1 is at the origin and the leads run along +X. The moulded front faces -Y (on the TO-92, the flat face), and the metal tab, exposed copper or mounting plate is at the back (+Y).

- **TO-220, TO-220F, TO-262, TO-251AA, TO-247 and TO-126.** The leads' shoulders rest on the board (the XY plane), and the leads continue their full length down through it.
- **TO-92.** The body sits 1.5 above the board (TI's reference seating plane).
- **TO-3.** The flange sits on the board, its mounting holes on a line along Y. Lead 2 is J along +X from lead 1, the holes' line is K back from lead 2, and the far hole is H from the leads' line, toward +Y. The leads are off the can's centre, as drawn.
- **TO-18, TO-39 and TO-46.** The flange sits on the board. Leads 1 and 3 are G apart along +X (2.54, or 5.08 on the TO-39), and lead 2 is H off that line along -Y (1.27, or 2.54). The tab is at 45°, beside lead 1.

`detail = "simple"` leaves out the leads.

## Source

Each table gives a minimum and a maximum. The part uses the middle of the two, except where noted. `part.py` holds every table as read.

- **Vishay Siliconix, "TO-220AB (High Voltage)"**, Package Information, document 92506, revision 30-Sep-2024 (DWG 6031), from vishay.com.
  - Page 1, drawing: front, side and back views and section F-F.
  - Page 2, table (mm): A 4.25–4.65, A1 1.20–1.34, A2 2.563–2.92, b 0.71–0.91, b2 1.14–1.78, c 0.46–0.61, D 14.32–15.86, D1 8.39–8.79, D2 12.20–12.80, E 9.96–10.36, E1 8.14–8.74, E2 0.59–0.69, e 2.54, e1 5.08, H1 6.30–6.70, L 13.40–14.40, L1 3.65–4.05, ØP 3.60–3.80, Q 2.54–2.94.
- **Vishay Semiconductors, "TO-220AC"**, Outline Dimensions, document 95221, revision 16-Jan-2026, from vishay.com. The drawing and table use the same letters. Here e1 is 4.88–5.28, the spacing of the two leads, and E2 is 0.76 max. The outline conforms to JEDEC TO-220AC.
- **Vishay Siliconix, "I2PAK (TO-262) (High Voltage)"**, Package Information, document 91367, revision 27-Oct-08 (DWG 5977), from vishay.com. Table (mm): A 4.06–4.83, A1 2.03–3.02, b 0.51–0.99, b2 1.14–1.78, c 0.38–0.74, c2 1.14–1.65, D 8.38–9.65, D1 6.86 min, E 9.65–10.67, E1 6.22 min, e 2.54, L 13.46–14.10, L1 1.65 max, L2 3.56–3.71. Where the table gives only a minimum or a maximum, the part uses it.
- **Vishay Siliconix, "Case Outline for TO-251AA (High Voltage)"**, Package Information, document 91362, revision 27-Dec-2021 (ECN E21-0682 rev C, DWG 5968), from vishay.com. The part uses Option 1, page 1. Table (mm): A 2.18–2.39, A1 0.89–1.14, b 0.64–0.89, b2 0.76–1.14, b4 4.95–5.46, c 0.46–0.61, c2 0.46–0.86, D 5.97–6.22, D1 5.21 min, E 6.35–6.73, E1 4.32 min, e 2.29, L 8.89–9.65, L1 1.91–2.29, L2 0.89–1.27, L3 1.14–1.52, θ2 25°–35°. Where the table gives only a minimum, the part uses it. The outline conforms to JEDEC TO-251AA.
- **Vishay Siliconix, "TO-247AC (High Voltage)"**, Package Information, document 91360, revision 07-Sep-2026, from vishay.com. The part uses version 1 (facility code 9) with its nominal values:
  - A 5.02, A1 2.41, A2 1.27, b 1.20, b2 2.00, b4 3.00, c 0.50, D 20.55, D1 16.76, D2 0.66, E 15.70, E1 14.02, E2 4.91, e 5.46, L 15.15, L1 4.06, ØP 3.61, ØP1 7.19 (ref), Q 5.50.
  - The package reference is JEDEC TO-247, variation AC.
- **Texas Instruments, LP0003A "TO-92 - 5.34 mm max height"**, drawing 4215214/C 04/2025 (ti.com/lit/pdf/msot002), straight lead option, page 1:
  - body 4.44–5.21 wide, 4.32–5.34 high and 3.17–4.19 deep;
  - the round back 2.03–2.67 from the leads, and the flat face at least 3.43 wide;
  - leads 0.38–0.55 x 0.35–0.43, at 1.27 ±0.13 pitch, 12.7 min long;
  - the seating plane (1.5) typical below the body;
  - reference JEDEC TO-226, variation AA.
- **Central Semiconductor, "Package Details - TO-3"** (REV R2, R0 9-April 2009), from centralsemi.com. The text doesn't extract, so the table was read from the rendered page. Table (mm): A flange length 38.50–39.96, B can Ø 19.00–22.23, C height above the flange's underside 6.35–11.43, D lead length 11.00–13.10, E flange thickness 1.38–1.65, F lead Ø 0.90–1.15, G holes apart 29.90–30.40, H the leads' line to the far hole 16.50–17.30, J lead 1 to lead 2 10.67–11.18, K lead 2 to the holes' line 5.21–5.72, L hole Ø 3.84–4.36, M flange width 25.00–26.67.
  - Central's "Material Composition Specification, TO-3 Case" (R3, 20-September 2018, from central.aeminc.com) gives a nickel-plated iron header and can and tin-plated terminals, 11.7 g on average.
- **Central Semiconductor, "Package Details - TO-18"** (REV R1, R0 21-June 2004) and **"TO-18 2-Lead Case"** (REV R0, 13-March 2013), from centralsemi.com.
  - Table (mm): A flange Ø 5.31–5.84, B can Ø 4.52–4.95, C flange 0.76 max (used as is), D height 4.32–5.33, E lead length 12.70 min (used as is), F lead Ø 0.41–0.48, G 2.54 (the lead circle, or the 2-lead part's spacing), H 1.27 (3 leads), and tab width 0.91–1.17 and tab length 0.71–1.22 at 45° (I and J; on the 2-lead sheet, H and J).
  - Both sheets' material sheets give a Kovar header and leads and a nickel-plated iron-alloy can.
- **Central Semiconductor, "Package Details - TO-39"** (REV R1, R0 21-June 2004) and **"Package Details - TO-46"** (REV R2, R0 17-July 2008), from centralsemi.com. The tables use the TO-18 sheet's letters:
  - TO-39 (mm): A flange Ø 8.51–9.40, B can Ø 8.00–8.51, C flange 1.02 max (used as is), D height 6.10–6.60, E lead length 12.70 min (used as is), F lead Ø 0.41–0.53, G 5.08 (the lead circle), H 2.54, I tab width 0.71–0.86, J tab length 0.74–1.14.
  - TO-46 (mm): A 5.31–5.84, B 4.52–4.95, C 1.02 max, D 1.65–2.16, E 12.70 min, F 0.41–0.53, G 2.54, H 1.27, and the tab width 0.91–1.17 and length 0.71–1.22 (its J and K).
- **Central Semiconductor, "Package Details - TO-126"** (REV R3, R0 21-June 2004), from centralsemi.com. Table (mm): A thickness 2.40–2.80, B the leads' centre plane 1.27 from the back, C lead thickness 0.38–0.75, D width 7.40–8.50, E hole centre 3.75 below the top, F hole Ø 3.00–3.40, G body height 10.50–12.00, H lead length 15.70 below the body, J lead width 0.62–0.90, K pitch 2.25 (L 4.50 from lead 1 to lead 3), M shoulder width 1.14–1.40, N shoulder length 2.10. "Mounting Plate Common to Pin 2", on the back.
- **Central Semiconductor, "Package Details - TO-220FP Case"** (REV R5, R2 06-June 2023) and **"TO-220FP-2 Case"** (REV R2, R0 28-January 2015), from centralsemi.com.
  - TO-220FP (mm): A thickness 4.20–5.12, B the top part's thickness 2.30–3.30, C the leads' centre plane 2.50–3.10 from the back, D lead thickness 0.80 max, E width 9.70–10.63, F the top part's height 6.06–7.00, G body height 14.80–16.25, H shoulder length 4.50 max, J lead length 12.78–13.80, K lead width 0.50–0.90, L pitch 2.54, M hole centre 2.55–3.55 below the top, N hole Ø 2.95–3.40, P shoulder width 1.00–1.47.
  - TO-220FP-2 (mm): A 4.80 max, B 3.12 max, C 2.50–2.90, D 0.81 max, E 10.31 max, F 6.30–6.90, G 14.80–15.40, H 4.10 max, J 13.00–13.80, K 0.90 max, L 2.55 (each lead from the centre line, so 5.10 apart), M 2.55–2.85, N 3.00–3.40, P 1.40 max. Where the sheets give only a maximum, the part uses it.

How the letters are read:

- **TO-220 and TO-247.** A2 (TO-247: A1) runs from the leads' back face to the back of the package. The leads' shoulders (b2, b4) are L1 long. On the TO-220, the metal tab is A1 thick: E wide above the moulding (H1 = D - D1), and E1 wide down the back to D2 below the top. On the TO-247, the exposed copper (D1 x E1, from D2 below the top) is taken as A2 thick, the dimension drawn at the back face. The TO-247's side slots are Ø E2, at Q below the top, the same height as the hole.
- **TO-92.** The body is a round of Ø W, cut flat at the depth T, with the leads K in front of the round back.
- **TO-18, TO-39 and TO-46.** The tab length J is read as reaching beyond the flange's edge.
- **TO-262.** A1 is read as on the TO-220: from the leads' back face to the back. The tab is c2 thick and flush with the back. It shows on the back as the thermal pad D1 x E1, from the body's top down (Section A-A), and rises L1 above the body. The shoulders (b2) are L2 long, and L is the lead's length from the body.
- **TO-251AA.** As on the TO-262, A1 runs from the leads' back face to the back, and the tab is c2 thick and flush with the back. The tab rises L2 above the body, b4 wide, and shows on the back as the thermal pad E1 wide, down to D1 below the tab's top (View A-A). L is the lead's length below the body. The leads are b2 wide for L1 below the body, then b wide: section C-C, which gives b2, is cut inside L1, and L3 (inside L1) is where the lead is uncontrolled. θ2 is the angle of the tab's corner chamfers.
- **TO-3.** The drawing's lower view looks from below, because the can is drawn dashed. Turned to look from above, with lead 2 along +X from lead 1, the far hole is toward +Y. C is the height from the flange's underside, and D the lead's length below it.
- **TO-220F.** The side view draws the body A thick up to F below the top, and above that B thick with the back face flush, so the hole is in the thinner part. H is the shoulder's length below the body, J the lead's from the body.
- **TO-126.** H is the lead's length from the body, shoulder included, and B runs from the back (the side the sheet marks "BACKSIDE") to the leads' centre plane.

**Proportions, for looks only.** The drawings show these but don't dimension them:

- The TO-220 tab's side notches, E2 deep, are 1.4 high, from 1.4 to 2.8 below the top, as drawn.
- The TO-262 tab above the body is the body's full width, with its top corners chamfered 0.04 x the width.
- The TO-251AA tab's corner chamfers, at θ2 = 30°, drop a third of L2, as drawn.
- The TO-3, TO-18, TO-39 and TO-46 cans are shells, closed at the top and open into the header. No sheet gives the wall, so it is a proportion fitted to the can's weight on Central's material sheets, at the model's density and rounded to 0.01 mm:
  - TO-3: 0.44, for a 2,537 mg can (sheet 2,550 mg; R3, 20-September 2018). With the flange and leads, the part weighs 10.42 g. The sheet gives 11.7 g for the whole device, of which 10.30 g is the header and can; the rest is tin plating, die coating and the die.
  - TO-18 and TO-18-2: 0.20, for a 114 mg can (sheet 114.99 and 115 mg; R4, 10-February 2020, and R0, 8-March 2013). The parts weigh 339 and 321 mg (sheet 312.4 and 287 mg).
  - TO-39: 0.25, for a 356 mg can (sheet 350 mg; R4, 16-July 2018). The part weighs 993 mg (sheet 1,006 mg).
  - TO-46: 0.70, for a 110 mg can (sheet 109.313 mg; R2, 16-July 2018). The can is only 0.89 high, so the wall is thick. The part weighs 399 mg, where the sheet gives 204 mg: the model's solid header and leads weigh 290 mg, where the sheet gives 84 mg for the header.
- The TO-3 flange outline is drawn but not dimensioned: it is read as round the holes (radius (A − G) / 2), round the centre (Ø M), and joined by tangent lines. The can's top edge is rounded 0.08 x B, as drawn.
- The TO-126's mounting plate on the back, drawn dashed in the front view, is 0.3 thick, set in 0.08 x the width from the sides and the top, and ends 0.1 x the height above the bottom.
- Not modelled: the TO-220AC's and TO-220FP-2's cut-off middle lead, the TO-220's and TO-251AA's ejector marks, the TO-251AA's lead-tip taper, the TO-247's copper ring ØP1, and the bodies' 5° draft and small radii.
- Every lead's shoulder narrows to the lead in one step.
- Materials are for looks and a rough mass:
  - The mouldings are epoxy. Nylon (PA6) is the nearest material in the list.
  - The TO-220 and TO-262 tabs, the TO-247 pad and the TO-126 plate are copper, and the leads are tinned copper.
  - The TO-18, TO-39 and TO-46 headers and leads are Kovar (8.36), so nickel (8.9), the nearest in the list. Their cans are steel.
  - The TO-3 header and can are iron, as Central's material sheet gives. The sheet names no other metal for the leads, so they are taken as iron too.

## Catalogue models

The reference models were measured against the drawings, and each falls inside the drawing's tolerances:

- **TO-220-3_Vertical.** 10.26 wide, 4.46 thick and 15.07 high with the tab. Leads 0.86 x 0.53 with 1.46 shoulders at 2.54. The leads' back face is 2.90 from the back.
- **TO-220-2_Vertical.** The same body, with leads at 0 and 5.08.
- **TO-247-3_Vertical.** 15.90 wide (E max 15.87, so 0.03 over), 5.03 thick and 20.7 high. Leads 1.20 with shoulders 2.03 and 3.00 at 5.45.
- **TO-92 and TO-92_Inline.** 4.83 wide, 3.75 deep. Leads at 1.27, with the flat face 1.33 in front of the leads and the round back 2.42 behind them.
- **TO-18-3.** Flange Ø 5.84, can Ø 4.95 and leads Ø 0.48 (the drawing's maximums). Lead 2 is 1.27 off the line of leads 1 and 3, and the tab is at 45° beside lead 1.

Added in 1.1.0, measured the same way:

- **TO-39-3.** Flange Ø 9.40 and can Ø 8.50 (the drawing's maximums), 6.5 high, leads Ø 0.48 on a Ø 5.08 circle with lead 2 2.54 off the line. The model has no tab; the drawing has one.
- **TO-46-3.** Flange Ø 5.84 with the 45° tab, can Ø 4.80 tapering to 4.73, 2.2 high (D max 2.16, so 0.04 over), leads Ø 0.48 on a Ø 2.54 circle with lead 2 1.27 off the line.
- **TO-126-3_Vertical.** 8.0 wide and 11.0 high, as drawn, but 3.25 thick where Central's drawing allows 2.40–2.80 (0.45 over). Leads 0.75 x 0.53 at 2.28 (Central 2.25, so 0.03 apart), their plane 1.25 from the back. Only the middle lead has a shoulder (1.6 wide), where Central draws one on every lead, 1.14–1.40 wide.
- **TO-220F-3_Vertical.** 10.16 wide, 4.70 thick, with the top part 2.54 thick, and 15.6 high. Leads 0.80 x 0.53 with 1.36 shoulders at 2.54. The leads' plane is 3.29 from the back, where Central's drawing gives 2.50–3.10 (0.19 over).
- **TO-220F-2_Vertical.** The same body, with leads at 0 and 5.08 (Central 5.10).

Added in 1.2.0:

- **TO-262-3_Vertical.** 10.01 wide, 4.50 thick, the body 8.85 high, and the tab 1.37 above it, 1.27 thick. Leads 0.80 x 0.50 with 1.27 shoulders at 2.54. The leads' back face is 2.40 from the back. These are all within Vishay's drawing, except that the model's shoulders are about 3.15 long (L2 3.56–3.71) and its leads reach 10.5 below the body (L 13.46–14.10).

Added in 1.3.0:

- **TO-251-3_Vertical.** 6.58 wide (E 6.35–6.73), 2.31 thick (A 2.18–2.39) and the body 6.08 high (D 5.97–6.22). The tab is 5.34 wide (b4 4.95–5.46) and 0.50 thick (c2 0.46–0.86). Leads 0.76 x 0.50 at 2.29, 9.58 below the body (L 8.89–9.65), with the leads' back face 1.03 from the back (A1 0.89–1.14). These are all within Vishay's drawing, except two:
  - the model's tab rises only 0.34 above the body across its width, with two 0.5 wide posts at its ends reaching 0.60 (L2 0.89–1.27);
  - its leads are 0.76 wide up to the body, with a 0.85 wide band from 1.4 to 2.2 below it (all inside b2's 0.76–1.14). Vishay's leads are b2 wide for L1 below the body, then b.
- **TO-3.** Can Ø 20.0 and 9.0 high (B 19.00–22.23, C 6.35–11.43), holes Ø 4.0 (L 3.84–4.36) 30.2 apart (G 29.90–30.40), leads Ø 1.0 (F 0.90–1.15) 10.9 apart (J 10.67–11.18), 16.9 from the far hole (H 16.50–17.30) and 1.8 off the can's centre. Its flange is 40.2 long, 27.2 wide and about 1.78 thick, where Central's drawing allows at most 39.96, 26.67 and 1.65. Its leads are 10.0 long below the flange (D 11.00–13.10, so 1.0 short).
- **TO-251-2_Vertical** is left out: Vishay's drawing has 3 leads only.

The names name the JEDEC package, so they map to the maker's drawing of it, with the pitch and lead order as named, and the differences are listed here.

The reference models stand their bodies at different heights above the board: the TO-92 at 2.5, and the TO-18, TO-39 and TO-46 at about 5. The drawings don't give these, so this part uses the drawings' own seating.

So these map: TO-220-3_Vertical (TO-220AB), TO-220-2_Vertical (TO-220AC), TO-247-3_Vertical (TO-247AC), TO-92 and TO-92_Inline (TO-92), TO-18-3 (TO-18), TO-18-2 (TO-18-2), TO-39-3 (TO-39), TO-46-3 (TO-46), TO-126-3_Vertical (TO-126), TO-220F-3_Vertical (TO-220F), TO-220F-2_Vertical (TO-220F-2), TO-262-3_Vertical (TO-262), TO-251-3_Vertical (TO-251AA) and TO-3 (TO-3).

These stay "no table read yet" (`COVERAGE.md`):

- the TO-92 models with leads formed to 2.54 (`_Wide`). TI's formed leads are 2.4 to 2.9 apart, with a land pattern of 2.6.
- the horizontal (bent-lead) models. The drawings give straight leads only.
- the 2-lead TO-39, TO-46, TO-126 and TO-251 models. Central's TO-39, TO-46 and TO-126 sheets, and Vishay's TO-251AA drawing, draw 3 leads only.
- the other packages in the family: TO-218, TO-220-4/5/11, TO-247-2/4/5, TO-262-3-1EP and TO-262-5, TO-264, TO-3P, TO-5, TO-8, TO-11 and TO-52, the TO-92 variants (L, S, Mini, Flat, 2-lead), and the windowed and lensed cans.