“TSSOP-8” refers to two genuinely different packages in the real supply chain: a 3.0 × 4.4 × 1.2 mm body under JEDEC MO-153 variation AA (used by TI, Renesas, Diodes, and others), and a smaller 3.0 × 3.0 × 1.1 mm body under NXP/Nexperia’s SOT505 family (used by parts like the LM75B temperature sensor). They share an 8-lead, 0.65 mm-pitch gull-wing layout and nothing else dimensionally. Confusing them is the single most common TSSOP-8 layout mistake.
Key takeaways
- Two real, non-interchangeable TSSOP-8 bodies exist: a wide 3.0 × 4.4 × 1.2 mm variant (JEDEC MO-153, variation AA) and a narrow 3.0 × 3.0 × 1.1 mm variant (NXP/Nexperia SOT505 family).
- Most low-quality package-spec pages blend numbers from both without realizing it — that’s why you’ll see “3×3mm,” “3×4.4mm,” and “4.4×3mm” all cited as “TSSOP-8” on the same aggregator site.
- Texas Instruments’ own PW0008A land pattern uses 1.5 mm × 0.45 mm pads on 0.65 mm centers with a 5.8 mm symmetric span — verified directly from TI’s package drawing, not estimated.
- At least two commercial TSSOP-8 breakout boards on the market are sized for the narrow 3×3mm variant — if your chip uses the wide body, it won’t physically fit.
- Pin numbering (1–8) is fixed by the outline; which signal sits on which pin is device-specific — the real LM75B pinout below illustrates why you always check the datasheet.
Mechanical Dimensions — Two Real Variants
Wide variant (JEDEC MO-153, variation AA — TI’s PW0008A, Renesas’s HU0008AA/M8.173, and the outline used by Diodes Inc. and Alpha & Omega Semiconductor):
| Parameter | Value |
| Body length (D) | 2.90–3.10 mm (typ. 3.00 mm) |
| Body width (E1) | 4.30–4.50 mm (typ. 4.40 mm) |
| Lead-tip span (E) | ~6.40 mm (6.2–6.6 mm per TI; 6.40 mm BSC per AOS) |
| Overall height (A, max) | 1.20 mm (real shipped parts range ~1.05–1.20 mm by manufacturer) |
| Lead pitch (e) | 0.65 mm BSC |
| Lead width (b) | 0.19–0.30 mm |
| Foot length (L) | 0.45–0.75 mm |
| Reference standard | JEDEC MO-153, variation AA |
Narrow variant (NXP/Nexperia SOT505 family — SOT505-1, -2, -3):
| Parameter | Value |
| Body length (D) | 2.9–3.1 mm (typ. 3.0 mm) |
| Body width (E) | 2.9–3.1 mm (typ. 3.0 mm) |
| Seated height (A, max) | 1.1 mm |
| Package height (A2) | 0.75–0.95 mm |
| Lead pitch (e) | 0.65 mm |
| Manufacturer code | SOT505 (issue date 2003-02-18 for -1) |
Both are real, currently used package families — this isn’t a legacy-vs-current split. TI’s TLC3702IPWR dual comparator and STMicroelectronics’ TS393IPT dual comparator both ship in the wide variant (distributor-listed at 3×4.4×1.15mm and 3.1×4.5×1.05mm respectively — note even these two “same package” parts differ slightly, which is normal manufacturer-to-manufacturer tolerance). NXP’s LM75B temperature sensor — one of the most common parts on embedded dev boards — ships in the narrow SOT505-1 variant.
Worked calculation — footprint area: Wide variant body area = 3.0 × 4.4 = 13.2 mm². Narrow variant body area = 3.0 × 3.0 = 9.0 mm². The narrow variant is roughly 32% smaller — meaningful if you’re comparing “TSSOP-8” options for a space-constrained design without realizing which one you’re actually looking at.
Why Two Variants Share One Name
TSSOP as a family (JEDEC MO-153) fixes lead pitch and lead style but not body width — that’s true across the whole family, not just at 8 leads. What’s unusual at the 8-lead count specifically is that two major, still-active package registries both landed on “TSSOP8” as a name: TI/Renesas/Diodes/AOS under the MO-153 variation AA outline, and NXP (later Nexperia) under its own SOT-series numbering (SOT505). Neither is deprecated. Neither is wrong. They’re just different packages that happen to share a marketing name.
| Attribute | Wide (MO-153 AA) | Narrow (SOT505) | SOIC-8 (reference) |
| Body (L × W) | 3.0 × 4.4 mm | 3.0 × 3.0 mm | ~4.9 × 3.9 mm (MS-012) |
| Max height | 1.20 mm | 1.10 mm | ~1.75 mm |
| Lead pitch | 0.65 mm | 0.65 mm | 1.27 mm |
| Typical package code | TI: PW0008A; Renesas: HU0008AA | NXP/Nexperia: SOT505-x | Widely multi-sourced |
| Example real part | TI TLC3702IPWR, ST TS393IPT | NXP LM75B, PCA9536 | — |
This is also why some vendor package codes you’ll encounter — Infineon’s PG-TSSOP-8-1 for gate-driver ICs, for instance — exist as yet another vendor-specific label under the same “TSSOP-8” umbrella. Don’t assume any two “TSSOP-8” datasheets are describing the same physical outline until you’ve checked the numbers.
Pin Numbering vs. Real Pinout: The LM75B Example
Numbering convention is fixed across both variants: viewed from the top with the pin-1 index mark at the upper left, pins run 1 through 4 down the left side and 5 through 8 up the right side, following the standard counter-clockwise gull-wing convention.
Function assignment is not fixed — it’s set per device. As a concrete, verified example, NXP’s LM75B digital temperature sensor (TSSOP8/SOT505-1, narrow variant) uses this real pinout, taken directly from NXP’s own application documentation:
| Pin | Function |
| 1 | SDA |
| 2 | SCL |
| 3 | OS (over-temperature shutdown output) |
| 4 | GND |
| 5 | A2 (address select) |
| 6 | A1 (address select) |
| 7 | A0 (address select) |
| 8 | VCC |
That’s one real device’s assignment. A comparator like the TS393IPT in the wide variant has an entirely different pin function map despite sharing the same 1–8 mechanical numbering convention. Always confirm against your specific part.
Footprint and Land Pattern — Verified TI Numbers
For the wide variant, Texas Instruments publishes an explicit land pattern for its PW0008A package (drawing 4221848, current as of the Feb-2015 revision):
- Pad size: 1.5 mm (length) × 0.45 mm (width), 8 pads
- Pad pitch: 0.65 mm, matching the lead pitch exactly
- Symmetric row-to-row span: 5.8 mm
- TI’s own stencil-design example uses matching dimensions, with the standard IPC-7351/IPC-7525 caveat that a fabrication site may specify alternate designs
For the narrow SOT505 variant, don’t reuse those numbers — a 5.8 mm span sized for a 4.4 mm body will leave pads sitting well outside a 3.0 mm-wide part. NXP publishes its own reflow-soldering footprint documentation specific to SOT505; pull that rather than approximating from the wide-variant numbers above.
The Breakout-Board Mismatch Trap
This is a genuinely common, avoidable mistake. At least two commercial hobbyist breakout boards — from ICBreakout and BC Robotics — are explicitly sold as “TSSOP-8 Breakout Board (3 × 3 mm, 0.65 mm),” sized for the narrow SOT505 body. If you’re prototyping with a wide-variant part (say, a TI comparator in PW0008A), that board’s pads won’t line up with your chip’s leads. Check the stated body dimensions on any breakout or adapter board before ordering — “TSSOP-8” alone isn’t specific enough.
Soldering, Reflow, and Handling
Lead-free small-outline packages, TSSOP included, commonly classify up to 260°C peak reflow temperature under J-STD-020, with the exact classification depending on package thickness and volume per that standard. Proto Advantage’s TSSOP-8-to-DIP adapter board is independently rated to the same +260°C maximum, consistent with that ceiling — though that figure describes the adapter board itself, not a guarantee for every IC that might sit on it, so confirm MSL and reflow profile against your specific part’s datasheet.
At 0.65 mm pitch, hand-soldering both variants is realistic with a fine-tip iron and flux, more so than the 0.5 mm-pitch packages you’ll find at higher TSSOP lead counts. It’s a step up in difficulty from SOIC-8’s 1.27 mm pitch, but well within reach for careful manual work or drag soldering.
Selection Path
- You’re laying out a footprint for a specific part → identify its exact package code from the datasheet (PW0008A/HU0008AA-style vs. SOT505-x) before generating anything — don’t infer it from the “TSSOP-8” name alone.
- You’re choosing a breakout/adapter board for prototyping → check its stated body dimensions (3×3mm vs. 3×4.4mm) against your chip’s datasheet, not just the “TSSOP-8” label.
- You want maximum board-area savings and your part is available in the narrow variant → it’s roughly 32% smaller than the wide variant for the same lead count.
- You need next-size-up gull-wing packages that keep the wide-variant footprint family → TSSOP-14/16/20 in the same MO-153 body-width tradition scale predictably; the narrow SOT505 family does not extend the same way.
FAQ
What is the body size of a TSSOP-8 package?
It depends which variant. The common JEDEC MO-153 variation AA body is 3.0 × 4.4 × 1.2 mm. NXP/Nexperia’s SOT505 family is 3.0 × 3.0 × 1.1 mm. Check your specific part’s package code, not just the “TSSOP-8” name.
Why doesn’t my TSSOP-8 breakout board fit my chip?
Some commercial breakout boards are sized for the narrow 3×3mm SOT505 variant. If your chip uses the wider 3.0×4.4mm MO-153 body, the pads won’t align. Confirm the board’s stated dimensions before ordering.
Is TSSOP-8 the same as SOIC-8?
No. SOIC-8 uses a 1.27 mm pitch and a roughly 4.9×3.9mm body per JEDEC MS-012, notably larger and coarser-pitch than either TSSOP-8 variant, with a taller ~1.75mm max profile.
What is the recommended TSSOP-8 PCB footprint?
For the wide MO-153 AA variant, TI’s own PW0008A land pattern uses 1.5×0.45mm pads on 0.65mm centers with a 5.8mm symmetric span. The narrow SOT505 variant needs its own, smaller footprint — don’t reuse the wide-variant numbers.
Can TSSOP-8 be hand-soldered?
Yes, on both variants. The 0.65mm pitch is manageable with a fine-tip iron and flux — easier than the 0.5mm pitch found on some higher-lead-count TSSOP packages.
What is the maximum reflow temperature for TSSOP-8?
Lead-free small-outline packages commonly classify up to 260°C peak under J-STD-020, with the exact figure depending on package thickness/volume. Verify against your specific part’s MSL rating and datasheet.
What to Do Next
Don’t design a TSSOP-8 footprint from the name alone. Pull your specific part’s datasheet, confirm its exact package code (a PW0008A/HU0008AA-style designator means the wide 3.0×4.4mm body; a SOT505-x designator means the narrow 3.0×3.0mm body), match the land pattern to that variant specifically, and verify any breakout or adapter board’s stated dimensions before you order one for prototyping.
Suggested internal links
- TSSOP vs SOIC vs SSOP package comparison → package selection guide
- How to read a JEDEC package outline drawing → package fundamentals
- IPC-7351 land pattern basics → PCB footprint design
- I2C sensor and expander ICs for embedded designs → component selection
External sources referenced
Texas Instruments PW0008A package/land pattern drawings (mpds568.pdf, cd40107b.pdf) · Alpha & Omega Semiconductor TSSOP8.pdf (PO-00003H) · Diodes Incorporated TSSOP-8.pdf · Renesas M8.173/HU0008AA package page · NXP SOT505-1 package page · NXP/Nexperia SOT505-2 and SOT505-3 documentation · NXP LM75B datasheet and application documentation · Pericom IC package MSL/reflow reference
