ATMEGA32A-AU Package Options: 44-Lead TQFP vs 40-Pin PDIP vs 44-Pad QFN/MLF

Scope: One Die, Three Package Types

The ordering code ATMEGA32A-AU identifies one specific package: a 44-lead TQFP, package type 44A. The same die is listed in other package types under different ordering codes — a 40-pin PDIP (40P6) and a 44-pad QFN/MLF (44M1). This article compares the mechanical options only, not the silicon, and every figure used below comes from the published fact sheet for this device.

That distinction matters at the purchasing stage. Engineering discussions often refer to "the ATmega32A" as if it were a single item, while the orderable item is a die plus a package plus an ordering code. Once a design is released, the package is no longer a detail for the layout team alone — it determines what the buyer puts on the BOM line, and it determines whether two lines on two different builds can be treated as the same thing. They cannot.

What Stays the Same: Core, Memory, Peripherals and Electrical Envelope

Because the silicon is common to all three packages, the functional baseline does not change when the package changes. Memory sizes, endurance, clocking, the peripheral set and the electrical envelope are properties of the die. Collecting them in one place makes the trade-off visible: what the buyer is choosing between is mechanical, not functional.

Two rows in that table deserve a buyer's attention because they are frequently misread. The endurance figures are stated separately for flash and EEPROM — 10000 flash cycles and 100000 EEPROM cycles — so a design that logs frequently to EEPROM and a design that rewrites program memory are working against different numbers. The retention figures are also paired with a temperature: 20 years at 85 °C and 100 years at 25 °C. Neither figure should be quoted without the temperature it belongs to. Similarly, the 16 MHz maximum oscillator frequency is qualified by a supply range of 4.5 V to 5.5 V, and the DC characteristics and start-up tables are written against a 5.0 V test condition.

This table is deliberately not repeated in the three package sections that follow, because none of these values change with the package. They are covered in depth elsewhere on this site. What changes is the package, the pin or pad count and the ordering code — and that is where the rest of this article stays.

Option 1: 44-Lead TQFP, Package Type 44A

This is the package the ATMEGA32A-AU ordering code itself denotes: package type 44A, a 44-lead TQFP with 44 pins. It is the reference point against which the other two options are compared, and it is the item a buyer receives when that exact ordering code is ordered.

The practical consequence for procurement is that the ordering code is the identifier, not a suffix that can be edited locally. The package type is part of what the code describes, so the BOM line must carry the full code as released by engineering. Shortening it, transcribing it from a similar line, or accepting a line where the code has been altered all move the purchase away from the item the design was validated against. When a BOM is cleaned up or transferred between systems, this is one of the fields that should be checked character by character rather than reviewed by eye.

For layout and manufacturing engineering, the 44-lead TQFP is the footprint that already exists in the released design if this ordering code was used. Any move to one of the other two options is a package change that reaches back into the footprint library, the assembly process and the approved BOM — not a purchasing-side substitution.

Option 2: 40-Pin PDIP, Package Type 40P6

The second option is the same die in a 40-pin PDIP, package type 40P6, supplied under its own ordering code. It is a through-hole package, which places it in a different assembly context from the surface-mount TQFP.

The number to hold onto is 40. The TQFP carries 44 pins; this package carries 40. That difference means a board designed around the 44-lead TQFP cannot simply accept the PDIP part, and the reverse is equally true. A change of this kind involves the footprint, the board itself and the assembly route, so it belongs in an engineering change process rather than in a buyer's judgement call.

There is a second point that is easy to miss. Because the pin count differs, the pin assignment must be confirmed against the datasheet's pinout drawing for the 40-pin PDIP. Carrying over the pin assignment from the 44-lead TQFP is not a valid assumption, even though the die is the same. Whoever writes the change documentation should cite the drawing they checked, so that the next reader does not have to repeat the exercise.

Option 3: 44-Pad QFN/MLF, Package Type 44M1

The third listed option is a 44-pad QFN/MLF, package type 44M1, again under its own ordering code.

The shared number here is a trap worth naming explicitly. The "44" in the QFN/MLF designation counts pads; the "44" in the TQFP designation counts pins. They are not the same thing, and the coincidence of the number does not mean the two are interchangeable or that the same footprint applies. Anyone scanning a BOM or a component list quickly could see 44, see 44, and assume a match. The package type designation — 44A versus 44M1 — is what actually distinguishes them.

Mechanical drawings for each package are published in the datasheet, and this article does not reproduce them. Layout engineers should work from those drawings rather than from any summary, including this one, when creating or verifying a footprint.

BOM and Footprint Checklist Before You Commit

The comparison reduces to a short set of checks that purchasing and layout can run together before a build is released. Each check is cheap; each failure is expensive after tooling or materials have moved.

• Confirm the exact ordering code. The ATMEGA32A-AU ordering code denotes one package. Record it in full, as released, without abbreviation or local convention.
• Confirm the package type designation. 44A for the 44-lead TQFP, 40P6 for the 40-pin PDIP, 44M1 for the 44-pad QFN/MLF. The designation is the field that resolves the ambiguity when the numbers look similar.
• Confirm the pin or pad count for that package. 44 pins on the TQFP, 40 pins on the PDIP, 44 pads on the QFN/MLF. Check the count against the package type, not against the number in the part description.
• Treat the three as separate orderable items. They cannot be substituted for one another without a documented, approved engineering change. A substitution that exists only in an email or a verbal instruction is not an approved change.
• Verify the footprint against the datasheet drawing. For any package change, re-derive the footprint rather than adapting the existing one, and re-check the pin assignment where the pin count differs.

The reason to make these checks explicit rather than assumed is that the functional baseline table earlier in this article is identical for all three options. Nothing in the electrical or peripheral data will flag a package mismatch. Only the ordering code, the package type designation and the pin or pad count will.

How to Request a Quote

NexCir can prepare a quotation against the exact item a design calls for. When you send a request, include for each BOM line the full ordering code and the package type designation required — for example, the ATMEGA32A-AU ordering code with package type 44A, or the corresponding ordering code for the 40-pin PDIP (40P6) or the 44-pad QFN/MLF (44M1). Stating the pin or pad count alongside the package type removes any ambiguity between the two 44-designated packages.

Requests are handled against the item as specified by Microchip Technology Inc. under the ordering code you provide, so the accuracy of the code on your BOM is what determines whether the quotation matches your design.

Related reading

• How Can You Secure Original ATMEGA32A-AU and ATMEGA64A-AU with Fresh Date Codes?
• ATMEGA32A-AU Peripherals and Interfaces: 8-Channel 10-Bit ADC, USART, SPI, I2C, Timers, PWM, and JTAG

References

1. ATmega32A Data Sheet Complete DS40002072A (2018)