How to Read STM32 Part Numbers — What Each Letter Means in STM32F103C8T6, F030F4P6, F411CEU6 (Pins, Flash, Package, Temperature)

Figure description: At the counter of an electronic-parts shop, a customer holds out two chips on his palm. One is marked STM32F103C8T6 and the other STM32F103CBT6. The customer asks, “What's the difference between C8T6 and CBT6?” A female clerk in a red apron points at the two chips and answers, “The flash is twice the size!”

STM32 is ST (STMicroelectronics)'s family of 32-bit Arm microcontrollers. The part numbers look long, but they spell out the family · pin count · flash size · package · temperature one character at a time, so once you know the rules you can tell what chip it is from the part number alone. Even within STM32F103, a single trailing character changes the flash size, package and operating temperature — and the price.

All values were checked against the Ordering information section of ST datasheets. Click a part number to find stock in eGuro Part Search.

1. One line, decoded (STM32F103C8T6)

The order is the same across all STM32 families: STM32 + type + sub-family + pin count + flash + package + temperature (+ options). STM32F103C8T6 means 'general-purpose F1, 103 sub-family, 48 pins, 64KB flash, LQFP, −40~85℃', and its neighbor STM32F103CBT6 is the same chip with flash doubled to 128KB.

2. Type letter — F · G · C · L · H

The three digits after the type letter are the sub-family. The datasheets describe 103 as 'Performance line', L051 as 'Access line', and F407 as 'a connectivity line that adds a camera interface and Ethernet to the 405'. You can't work out specs from the digits alone; pin count, flash and package vary within the same sub-family.

3. Pin count letter

Pin count letters mean almost the same thing across all of STM32. However, some pin counts don't exist in a given family (e.g., F103 has no 20-pin version), so check the table in that family's datasheet to confirm the combination actually exists.

4. Flash size letter

Flash is the memory that holds the program. Part numbers of the same chip that differ only in flash (e.g., STM32F103C8T6 64KB and STM32F103CBT6 128KB) have the same pinout, so the board stays the same, but a program larger than the flash won't fit. Prices differ too, so always check this one character when quoting.

5. Package letter

The most common are T = LQFP, P = TSSOP and U = QFN. Even at 48 pins, STM32F411CET6 (LQFP) and STM32F411CEU6 (QFN) differ in shape and size and can't replace each other. Package shapes and sizes are covered in the Component Package Names: A Complete Guide post.
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6. Temperature digit — 6 · 7 · 3

A bigger digit isn't better: 3 is the widest (125℃), then 7 (105℃), then 6 (85℃). Boards used in hot places such as factory equipment or power supplies use 7 or 3, so don't change the final digit when quoting.

7. Trailing characters — TR · programming · family-specific options

TR means the chips come wound on a reel (tape), ready to load straight onto an SMT pick-and-place machine. With no suffix, they come in trays or tubes. Even for the same chip, a different packing means a different order part number, and the minimum order quantity may differ too. In some families, extra letters such as D · A after the temperature digit mean different specs, so check that family's datasheet.

Figure description: A quote on the counter lists two lines, STM32F103C8T6 and STM32F103C8T7 TR. The customer asks, “Aren't they the same chip?” The female clerk circles the final 7 and TR in red with a pen and answers, “The final 7 means the 105℃ version, and TR means reel packing!” Next to them sit a tray and a reel holding chips.

8. The most confusing trap

In STM32 part numbers, the same letter means different things in different positions. For example, STM32F411CCU6 contains C twice: the first C is 48 pins and the second is 256KB flash. So the surest way to read a part number is to count positions in order, starting from the character after STM32. Some letters, like package letters H · I, also point to slightly different packages depending on the family, so do the final check with that family's datasheet.

9. Common part numbers decoded

All part numbers in the table end in 6, so their temperature range is −40~85℃.

Every part number in the table was decoded with the ordering information rules in its datasheet. A part number that differs by one character from a row can be read with the same rules. For example, STM32F103C8T7 is the same as STM32F103C8T6 except for the temperature, −40~105℃.

10. Reading the top marking

ST datasheets give a top-marking example for each package. Large chips such as LQFP have the part number split over two lines, with the date code below. Very small chips such as WLCSP carry an abbreviated part number (WLCSP49 example in the F411 datasheet: E411CEB), so the full part number is hard to tell from the top alone. The datasheets state that 'the printed markings may differ depending on the supply chain', and advise that chips marked ES or E are Engineering Samples not yet qualified for production and must not be used in products.

11. What to check when quoting or substituting

• Flash letter — one character, like 8 (64KB) vs B (128KB), changes price and capacity
• Pin count letter — C (48 pins) and R (64 pins) need different boards
• Package letter — even at the same pin count, T (LQFP) · U (QFN) · Y (WLCSP) can't replace each other
• Temperature digit — never replace 7 · 3 with 6
• Trailing characters — check that TR (reel) / tray packing and family-specific options like D · A also match
• Similar names from other companies — chips with similar names such as GD32F103 are not ST products but another company's, so check that company's datasheet separately

Sources: Ordering information and Device marking in the ST STM32F103x8/xB (DS5319) · STM32F030x4/6/8/C (DS9773) · STM32F405/407 (DS8626) · STM32F411xC/xE (DS10314) · STM32G030x6/x8 (DS12991) · STM32L051x6/x8 (DS10184) · STM32H742/743 (DS12110) · STM32C011x4/x6 (DS13866) datasheets. The letters used vary slightly by family, so check the relevant datasheet before placing an actual order.