The SSOP-28 package is a 28-lead shrink small outline package built for dense surface-mount boards. In its most common form it follows JEDEC MO-150: a 5.3 mm wide plastic body, 0.65 mm lead pitch, and about 2 mm of height. One thing trips people up. Two different JEDEC outlines are both sold as SSOP-28, so confirm the body width and lead span before you commit a footprint.
Key takeaways
- The common SSOP-28 is JEDEC MO-150: 5.3 mm body, 0.65 mm pitch, about 2 mm tall, 7.8 mm lead span (per NXP SOT341-1).
- A narrower part is also labeled SSOP-28: the 0.150 in (3.9 mm) body, 0.025 in (0.635 mm) pitch outline of JEDEC MO-137, more often called QSOP.
- A safe reflow land is 0.40 mm × 1.60 mm pads on 0.65 mm pitch (NXP SOT341-1).
- FT232RL is the reference part most engineers picture: 5.30 × 10.20 mm body, 0.65 mm pitch, now marked NRND by FTDI.
- Choose TSSOP-28 when height must stay under 1.2 mm; choose SOIC-28 wide when hand rework matters more than board area.
What “SSOP-28” actually refers to
An SSOP-28 is a 28-lead shrink small outline package with gull-wing leads on two sides. The most common version follows JEDEC MO-150: a 5.3 mm wide body, 0.65 mm lead pitch, and a seated height of about 2 mm.
The complication is that JEDEC registered two SSOP families that both include a 28-pin member. MO-150 is the 5.3 mm body, 0.65 mm pitch outline (per the JEDEC JEP95 index). MO-137 is the 0.150 in (3.9 mm) body, 0.025 in (0.635 mm) pitch outline, and its device list runs 14, 16, 18, 20, 24, 28 pins. Most vendors call the MO-137 part a QSOP, but some distributors still list it as SSOP-28.
The practical tell is body width and lead span, not pitch, since 0.65 mm and 0.635 mm are almost the same spacing. If the drawing shows a 5.3 mm body and a 7.6 to 7.9 mm lead span, it is MO-150. If it shows a 3.9 mm body and roughly a 6 mm span, it is the MO-137 or QSOP land, and its footprint is not interchangeable with the 5.3 mm part.
The MO-150 title also fixes a 1.25 mm lead length alongside the 0.65 mm pitch, which is what the JEDEC shorthand R-PDSO-G28 encodes for this outline. Keep that designator handy when you search a library, because it disambiguates the part faster than the words SSOP-28 do.
[IMAGE 1: dimensioned SSOP-28 top and side view | alt: “SSOP-28 package dimensions diagram showing 5.3 mm body, 0.65 mm pitch and 2 mm height”]
SSOP-28 dimensions (MO-150)
These are the full mechanical limits from the NXP SOT341-1 drawing, the registered MO-150 outline for a 28-lead 5.3 mm body. All values in mm.
| Symbol | Parameter | Min | Nom | Max |
| A | Overall seated height | – | – | 2.00 |
| A1 | Standoff | 0.05 | – | 0.21 |
| A2 | Body thickness | 1.65 | 1.73 | 1.80 |
| b | Lead width | 0.25 | – | 0.38 |
| c | Lead thickness | 0.09 | – | 0.20 |
| D | Body length | 10.00 | 10.20 | 10.40 |
| E | Body width | 5.20 | 5.30 | 5.40 |
| e | Lead pitch | – | 0.65 | – |
| HE | Lead span (tip to tip) | 7.60 | 7.80 | 7.90 |
| L | Foot length | 0.70 | – | 1.10 |
| θ | Foot angle | 0° | – | 8° |
Two numbers matter most for fit. The 7.8 mm nominal lead span sets how far your outer pads sit apart, and the 2.0 mm maximum height sets your z-clearance under shields or stacked boards. The body itself is nominally 10.2 × 5.3 mm.
SSOP-28 pinout and pin numbering
The 28 leads run 14 per side. Pin 1 is marked by an index dot or a bevel on the body, and numbering runs counterclockwise when you view the package from the top. Pins 1 through 14 go down the left side, and pins 15 through 28 come up the right, so pin 15 sits opposite pin 14 and pin 28 sits opposite pin 1.
That geometry is fixed by the package. The function of each pin is not. Power, ground, and signal assignments belong to the specific device, so read the device datasheet rather than assuming a layout. The FTDI FT232RL and an Analog Devices data converter can share the SSOP-28 outline and share nothing about pin roles.
[IMAGE 2: SSOP-28 pinout numbering | alt: “SSOP-28 pinout diagram with pin 1 index dot and counterclockwise numbering 1 to 28”]
SSOP-28 footprint and land pattern
For the MO-150 part, the NXP SOT341-1 reflow footprint gives a clean starting land: rectangular pads 0.40 mm wide by 1.60 mm long, on 0.65 mm pitch, with a total occupied area near 11.8 × 8.85 mm including courtyard. That maps to an IPC-7351 nominal (density level B) land for a 0.65 mm gull-wing part.
A few build notes follow from the 0.65 mm pitch. Keep a solder-mask dam of roughly 0.1 to 0.15 mm between pads where the fab can hold it, since bridging is the main defect at this pitch. A 0.12 to 0.15 mm stencil with a 1:1 aperture on the pad works for most SSOP-28 parts. Escape routing is manageable on two layers because one trace fits between adjacent pads at typical design rules, though four layers help once you route all 28 nets.
The standoff (A1) runs only 0.05 mm to 0.21 mm on this outline, so the body sits close to the board with a thin solder fillet under it. Keep the occupied area clear of tall neighbors, and leave room for inspection since the joints are visible at the lead toes rather than hidden under the package.
| Land parameter | Value | Source |
| Pad width | 0.40 mm | NXP SOT341-1 |
| Pad length | 1.60 mm | NXP SOT341-1 |
| Pad pitch | 0.65 mm | NXP SOT341-1 |
| Occupied area | ≈ 11.8 × 8.85 mm | NXP SOT341-1 |
[IMAGE 3: SSOP-28 recommended reflow land pattern | alt: “SSOP-28 footprint land pattern with 0.40 mm by 1.60 mm pads on 0.65 mm pitch”]
SSOP-28 vs TSSOP-28, QSOP-28 and SOIC-28
Same pin count, different mechanics. The table below sets the 5.3 mm SSOP-28 against the parts it competes with on a real board. Body widths and pitches trace to the JEDEC JEP95 index and the cited datasheets; heights are datasheet maxima where sourced and typical figures where marked.
| Attribute | SSOP-28 (MO-150) | TSSOP-28 (MO-153) | QSOP / SSOP-28 150 mil (MO-137) | SOIC-28 wide (MS-013) |
| Body width | 5.3 mm | 4.4 mm | 3.9 mm (0.150 in) | 7.5 mm |
| Lead pitch | 0.65 mm | 0.65 mm | 0.635 mm (0.025 in) | 1.27 mm |
| Max height | 2.0 mm | 1.2 mm | ~1.75 mm | ~2.65 mm (typ) |
| Lead span | ~7.8 mm | ~6.4 mm | ~6.0 mm | ~10.3 mm |
| Best when | mixed-signal, UART, PMIC | thin, height-limited builds | fine-pitch legacy logic | easy hand rework, wider traces |
Read it as a decision. If your part is a mainstream mixed-signal or interface chip and height is not tight, the 5.3 mm SSOP-28 is the default. Drop to TSSOP-28 when the lid clearance is under about 1.5 mm. Move up to SOIC-28 wide when the board has room and you want the 1.27 mm pitch for hand assembly and fatter power traces.
ICs you’ll meet in an SSOP-28
The FTDI FT232RL USB-to-UART bridge is the canonical example: a 28-lead SSOP with a 5.30 × 10.20 mm body, 7.80 × 10.20 mm including leads, and 0.65 mm pitch, rated −40 °C to +85 °C at 3.3 V to 5.25 V. Worth knowing before you design it in: FTDI now lists the FT232RL as NRND (not recommended for new designs), so plan a second source.
Beyond it, the outline shows up across vendors. Infineon builds PSoC 4100S microcontrollers in its PG-SSOP-28-800, which is the SSOP-28 body. Analog Devices and Linear use the G package, a 28-lead 5.3 mm SSOP (Linear drawing 05-08-1640), for regulators and converters. Classic RS-232 line drivers such as the SP213 family also ship in 28-lead SSOP, which is why an FT232RL plus a level translator was a standard serial-port pairing.
Design, soldering and assembly notes
Standard MO-150 SSOP-28 has no exposed thermal pad, so heat leaves through the leads and copper. Size your dissipation from the datasheet θJA using Tj = Ta + (P × θJA). At Ta = 50 °C, P = 0.5 W, and θJA = 90 °C/W, junction temperature lands near 95 °C, comfortably under a 125 °C limit. If your budget is tighter, add copper pour on the pins that the datasheet flags as thermal.
Assembly is routine SMT. A lead-free reflow peak of roughly 245 °C suits most SSOP-28 parts, and moisture-sensitive devices should be baked or kept within their MSL floor-life window before reflow. Hand soldering is realistic with a fine tip and flux; drag soldering plus solder wick clears bridges quickly at 0.65 mm pitch.
Frequently asked questions
How many pins does an SSOP-28 have and how are they arranged?
Twenty-eight leads, 14 per side, in a dual-row gull-wing layout. Pin 1 is at the index mark, and numbering runs counterclockwise from the top view, so pins 1 to 14 run down one side and 15 to 28 up the other.
What is the pitch of an SSOP-28 package?
The common MO-150 SSOP-28 uses a 0.65 mm lead pitch. The look-alike MO-137 or QSOP part uses 0.025 in, which is 0.635 mm. The two spacings are close enough to confuse, so check body width to tell them apart.
Is SSOP-28 the same as TSSOP-28?
No. They share the 0.65 mm pitch and 28 pins, but SSOP-28 has a 5.3 mm body and about 2 mm height, while TSSOP-28 has a 4.4 mm body and stays under 1.2 mm. Their land patterns and lead spans differ, so the footprints are not interchangeable.
Can you hand solder an SSOP-28?
Yes. At 0.65 mm pitch it is one of the more forgiving fine-pitch packages. Use a fine tip, plenty of flux, and clear any bridges with solder wick. A breakout adapter to 2.54 mm headers helps for prototyping.
What footprint should I use for an SSOP-28?
For the 5.3 mm MO-150 part, start from 0.40 mm × 1.60 mm pads on 0.65 mm pitch (NXP SOT341-1), then confirm against your specific device datasheet. If the part is the 3.9 mm 150-mil variant, use the QSOP land instead.
What to do next
Default to the 5.3 mm MO-150 footprint whenever the part is a mainstream mixed-signal, interface, or power chip and height is not constrained. Before you route it, open the device drawing and confirm the lead span reads 7.6 to 7.9 mm. If it instead shows a 3.9 mm body and a span near 6 mm, you have the QSOP or MO-137 land and need that footprint, not this one. When lid clearance drops under about 1.5 mm, switch to TSSOP-28, and when you value hand rework over area, step up to SOIC-28 wide.
