ATMEGA168PA-AU from Microchip, in a TQFP-32(7x7). Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	PD3/PCINT19/OC2B/INT1	bidirectional	Port D bit 3 GPIO with internal pull-up. Alternate: External interrupt INT1, Timer/Counter2 output compare match B (OC2B), pin-change interrupt PCINT19.
2	PD4/PCINT20/XCK/T0	bidirectional	Port D bit 4 GPIO with internal pull-up. Alternate: USART external clock (XCK), Timer/Counter0 external counter input (T0), pin-change interrupt PCINT20.
3	GND	power_in	Digital ground reference (0V).
4	VCC	power_in	Digital supply voltage, 1.8V to 5.5V.
5	GND	power_in	Digital ground reference (0V).
6	VCC	power_in	Digital supply voltage, 1.8V to 5.5V.
7	PB6/PCINT6/XTAL1/TOSC1	bidirectional	Port B bit 6 GPIO. Alternate: crystal oscillator input (XTAL1) or Timer/Counter2 async oscillator input (TOSC1); pin-change interrupt PCINT6.
8	PB7/PCINT7/XTAL2/TOSC2	bidirectional	Port B bit 7 GPIO. Alternate: crystal oscillator output (XTAL2) or Timer/Counter2 async oscillator output (TOSC2); pin-change interrupt PCINT7.
9	PD5/PCINT21/OC0B/T1	bidirectional	Port D bit 5 GPIO. Alternate: Timer/Counter0 output compare B (OC0B), Timer/Counter1 external counter input (T1), pin-change interrupt PCINT21.
10	PD6/PCINT22/OC0A/AIN0	bidirectional	Port D bit 6 GPIO. Alternate: Timer/Counter0 output compare A (OC0A), analog comparator positive input (AIN0), pin-change interrupt PCINT22.
11	PD7/PCINT23/AIN1	bidirectional	Port D bit 7 GPIO. Alternate: analog comparator negative input (AIN1), pin-change interrupt PCINT23.
12	PB0/PCINT0/CLKO/ICP1	bidirectional	Port B bit 0 GPIO. Alternate: divided system clock output (CLKO), Timer/Counter1 input capture (ICP1), pin-change interrupt PCINT0.
13	PB1/PCINT1/OC1A	bidirectional	Port B bit 1 GPIO. Alternate: Timer/Counter1 output compare A (OC1A) PWM, pin-change interrupt PCINT1.
14	PB2/PCINT2/SS/OC1B	bidirectional	Port B bit 2 GPIO. Alternate: SPI slave select (SS, active low), Timer/Counter1 output compare B (OC1B), pin-change interrupt PCINT2.
15	PB3/PCINT3/OC2A/MOSI	bidirectional	Port B bit 3 GPIO. Alternate: SPI master-out/slave-in (MOSI), Timer/Counter2 output compare A (OC2A), pin-change interrupt PCINT3.
16	PB4/PCINT4/MISO	bidirectional	Port B bit 4 GPIO. Alternate: SPI master-in/slave-out (MISO), pin-change interrupt PCINT4.
17	PB5/SCK/PCINT5	bidirectional	Port B bit 5 GPIO. Alternate: SPI serial clock (SCK), pin-change interrupt PCINT5. Also ISP programming clock.
18	AVCC	power_in	Analog supply pin for the A/D converter, PC3:0, and ADC7:6. Must be externally connected to VCC (through a low-pass filter if ADC is used) even if the ADC is not used.
19	ADC6	input	10-bit analog input channel 6 to the A/D converter. Powered from AVCC. Available only in TQFP and QFN/MLF packages.
20	AREF	passive	Analog reference voltage input for the A/D converter.
21	GND	power_in	Digital ground reference (0V).
22	ADC7	input	10-bit analog input channel 7 to the A/D converter. Powered from AVCC. Available only in TQFP and QFN/MLF packages.
23	PC0/ADC0/PCINT8	bidirectional	Port C bit 0 GPIO. Alternate: ADC channel 0 input (ADC0), pin-change interrupt PCINT8.
24	PC1/ADC1/PCINT9	bidirectional	Port C bit 1 GPIO. Alternate: ADC channel 1 input (ADC1), pin-change interrupt PCINT9.
25	PC2/ADC2/PCINT10	bidirectional	Port C bit 2 GPIO. Alternate: ADC channel 2 input (ADC2), pin-change interrupt PCINT10.
26	PC3/ADC3/PCINT11	bidirectional	Port C bit 3 GPIO. Alternate: ADC channel 3 input (ADC3), pin-change interrupt PCINT11.
27	PC4/ADC4/SDA/PCINT12	bidirectional	Port C bit 4 GPIO. Alternate: ADC channel 4 input (ADC4), TWI (I2C) data line (SDA, open-drain), pin-change interrupt PCINT12.
28	PC5/ADC5/SCL/PCINT13	bidirectional	Port C bit 5 GPIO. Alternate: ADC channel 5 input (ADC5), TWI (I2C) clock line (SCL, open-drain), pin-change interrupt PCINT13.
29	PC6/RESET/PCINT14	input	Reset input (active-low): a low level longer than the minimum pulse width generates a reset even if the clock is not running. When the RSTDISBL fuse is programmed, this pin becomes GPIO PC6 with weaker drive characteristics than other Port C pins.
30	PD0/RXD/PCINT16	bidirectional	Port D bit 0 GPIO. Alternate: USART receive data input (RXD), pin-change interrupt PCINT16.
31	PD1/TXD/PCINT17	bidirectional	Port D bit 1 GPIO. Alternate: USART transmit data output (TXD), pin-change interrupt PCINT17.
32	PD2/INT0/PCINT18	bidirectional	Port D bit 2 GPIO. Alternate: external interrupt INT0, pin-change interrupt PCINT18.

Key specifications

Parameter	Value
Manufacturer	Microchip
Package	TQFP-32(7x7)
Category	MCU
Pins	32

Ordering variants

ATMEGA168PA-AU
ATMEGA168PA-AUR
ATMEGA168PA-AUMU
ATMEGA168PA-AUMUR
ATMEGA168PA-AUPU
ATMEGA168PA-AUMMH
ATMEGA168PA-AUCU

CAD (KiCad official)

Symbol: ATMEGA168PA-AU
Footprint: Package_QFP:LQFP-32_7x7mm_P0.8mm
3D model: TQFP-32(7x7) (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`atmega168pa-au.step`	413 KB	You want the bare part, or you mark your own boards.
`atmega168pa-au-etched.step`	3.5 MB	You want the part with `ATMEGA168PA-AU` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 911 faces against 507 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Microchip datasheet (31 pp, sha256 194fdd0f35c63d3b, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF