The MSOP-12 package is a 12-lead Mini Small Outline Package, and in practice it means one specific thing: Analog Devices’ MSE package, a thermally enhanced MSOP with an exposed pad. It has a 3.0 mm × 4.04 mm body, a 0.65 mm lead pitch, and a maximum height of 1.10 mm. The pitch is the first thing engineers get wrong — it is 0.65 mm, not the 0.50 mm used by the MSOP-10. This page gives the verified dimensions, the pin numbering with a real pinout, and a recommended land pattern.
Key takeaways
- The MSOP-12 (Analog Devices MSE) has a 3.0 mm × 4.04 mm body, is 4.90 mm wide across the gull-wing leads, and is 1.10 mm tall at most.
- Lead pitch is 0.65 mm — the same as the MSOP-8, but wider than the MSOP-10’s 0.50 mm, which is a common source of footprint errors.
- The package has an exposed thermal pad on the underside, numbered pin 13, that must be soldered to a ground pour.
- Real MSOP-12 parts are the Analog Devices LT3045 and LT3094 ultralow-noise LDOs (order codes ending in MSE), rated to 150 °C junction.
- Several distributor pages list the MSOP-12 as 3.0 × 3.0 mm, or 0.50 mm pitch, or call it “leadless”; all three are wrong for this part.
Is MSOP-12 a standard package?
The MSOP family standardizes cleanly at 8, 10, and 16 leads under JEDEC MO-187, but the 12-lead is uncommon. Texas Instruments’ mainstream VSSOP line, the same footprint under a different name, runs 8, 10, and 16 leads and does not offer a 12. In practice, when a datasheet says “MSOP-12,” it almost always means the Analog Devices (originally Linear Technology) MSE package: a 12-lead plastic MSOP with an exposed die pad.
Because it is not a widely second-sourced size, the specifications you find online conflict. The authoritative numbers come from the package drawing on the parts that use it — Analog Devices drawing 05-08-1666 — not from distributor category pages.
MSOP-12 dimensions
The MSOP-12 (Analog Devices MSE) has a 3.0 mm × 4.04 mm plastic body, measures 4.90 mm across the gull-wing leads, and stands 1.10 mm tall at most, with a 0.65 mm lead pitch and an exposed thermal pad of 2.845 mm × 1.651 mm on the underside. Values come from Analog Devices package drawing 05-08-1666.
| Symbol | Dimension | Value (mm) |
| A | Overall height (max) | 1.10 |
| A2 | Molded body thickness | 0.86 (ref) |
| b | Lead width | 0.22–0.38 |
| c | Lead thickness | 0.05–0.15 |
| D | Body length | 4.039 ±0.102 |
| E | Overall width (incl. leads) | 4.90 ±0.152 |
| E1 | Body width | 3.00 ±0.102 |
| e | Lead pitch | 0.65 BSC |
| — | Exposed pad | 2.845 × 1.651 |
Values are from the Analog Devices “MSE Package, 12-Lead Plastic MSOP, Exposed Die Pad” drawing 05-08-1666 Rev G, as printed on the LT3045 and LT3094 datasheets.
MSOP-12 pinout: how the pins are numbered
An MSOP-12 has six leads per side. Pin 1 is at the top-left index mark, and the count runs counterclockwise: pins 1 to 6 down the left edge, then 7 to 12 up the right. The exposed pad on the underside is numbered pin 13.
As with any package, the pin functions are set by the device, not the outline, so take them from the specific datasheet.
| Pin | Name | Function (example: Analog Devices LT3045, MSE) |
| 1 | IN | Input supply |
| 5 | PG | Power good, open-collector flag |
| 6 | ILIM | Current-limit programming |
| 7 | PGFB | Power-good feedback |
| 9 | GND | Ground |
| 12 | OUT | Regulated output |
| 13 | Exposed pad | GND; must be soldered to the PCB |
Selected pins shown from the LT3045 datasheet; the remaining pins are omitted here. On this part the exposed pad is pin 13, a ground connection that must be soldered down for the device to work.
MSOP-12 footprint and land pattern
The land pattern is twelve pads at 0.65 mm pitch, six per side, plus a central thermal land under the exposed pad. Analog Devices’ recommended solder pad layout for the MSE uses a thermal land of about 2.65 mm × 1.70 mm and an overall signal-pad span near 5.10 mm, with individual pads about 0.42 mm wide.
| Feature | Value |
| Pad pitch | 0.65 mm |
| Pads | 12 (6 per side) |
| Signal pad width | ~0.42 mm |
| Thermal land (exposed pad) | ~2.65 mm × 1.70 mm |
| Overall land span | ~5.10 mm (min) |
Because the exposed pad is both the ground connection and the heat path, tie it to an inner ground plane with a via array under the part. The payoff is thermal: on the LT3045, Analog Devices specifies the MSE package at about 33 °C/W junction-to-ambient and 8 °C/W junction-to-case, with a 150 °C maximum junction temperature — figures that depend on the pad being soldered to copper.
Real parts and sourcing
The MSOP-12 is narrow in scope, so the parts that use it are worth naming. The Analog Devices LT3045 (positive) and LT3094 (negative) ultralow-noise LDOs ship in the 12-lead MSE, as does the automotive-qualified LT3045-EP; order codes carry the MSE suffix, for example LT3045EMSE. Availability tracks those parts rather than a broad multi-vendor market, so there is little cross-vendor second-sourcing for the exact package. If your design needs only the function and not this outline, check whether a 10-lead MSOP or a DFN version of the part covers it instead.
Where the spec sheets go wrong
Distributor package pages disagree on the MSOP-12, and some are simply wrong. One lists it as 3.0 × 3.0 mm with 0.50 mm pitch; another gives 0.65 mm pitch but keeps the 3.0 × 3.0 mm body; several describe it as having “leadless edge contacts” or “bottom-terminal contacts.” The Analog Devices drawing settles it: the body is 3.0 × 4.04 mm, the pitch is 0.65 mm, and the leads are gull-wing, with an exposed pad added underneath. Draw the footprint from the drawing, not the listing.
Frequently asked questions
Is MSOP-12 a standard package?
Not a common one. The MSOP family is standardized at 8, 10, and 16 leads under JEDEC MO-187; the 12-lead is uncommon and, in practice, refers to the Analog Devices MSE package, a 12-lead plastic MSOP with an exposed die pad. Texas Instruments’ VSSOP line does not offer a 12-lead size.
What are the dimensions of an MSOP-12?
The Analog Devices MSE (MSOP-12) has a 3.0 mm × 4.04 mm body, is 4.90 mm wide across the gull-wing leads, and stands 1.10 mm tall at most, with a 0.65 mm lead pitch and a 2.845 mm × 1.651 mm exposed pad. Values are from Analog Devices drawing 05-08-1666.
What is the pitch of an MSOP-12 package?
The MSOP-12 uses a 0.65 mm lead pitch, matching the MSOP-8 but wider than the MSOP-10’s 0.50 mm. Distributor pages that list 0.50 mm for the 12-lead are incorrect for the Analog Devices MSE package.
What parts use the MSOP-12 package?
The Analog Devices LT3045 and LT3094 ultralow-noise LDOs use the 12-lead MSE, as does the LT3045-EP. Order codes carry an MSE suffix, such as LT3045EMSE. The package is narrow in scope and is not broadly second-sourced.
How are MSOP-12 pins numbered?
Pin 1 is at the top-left index mark, and the count runs counterclockwise: pins 1 to 6 down the left side, then 7 to 12 up the right. The exposed thermal pad on the underside is numbered pin 13. Pin functions come from the specific device datasheet.
Does the MSOP-12 have an exposed pad?
Yes. The Analog Devices MSE version has an exposed die pad on the underside, numbered pin 13 and tied to ground, which must be soldered to a copper pour for the device to work and to reach its rated thermal resistance.
What to do next
Treat “MSOP-12” as the Analog Devices MSE package unless a datasheet tells you otherwise: a 3.0 × 4.04 mm body, 0.65 mm pitch, 1.10 mm tall, with a ground-tied exposed pad as pin 13. Draw the footprint from Analog Devices drawing 05-08-1666, take the pinout from the specific part such as the LT3045, and solder the exposed pad to a via-stitched ground plane. If the function exists in a 10-lead MSOP or a DFN, weigh that too, because the 12-lead is a narrow, largely single-source package.
