AVR32DB28-I from Microchip Tech, in a SSOP-28. 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	PA7	bidirectional	General-purpose I/O port A pin 7. Alternate functions: CLKOUT (system clock output), CCL LUT0/LUT1/LUT2 OUT, TCB0 XDIR (alt), SPI0 SS (alt), TCD0 WOD, EVSYS EVOUTA (alt). Supports asynchronous external interrupt detection.
2	PC0	bidirectional	General-purpose I/O port C pin 0 in the VDDIO2 power domain (MVIO). Alternate functions: USART1 TxD, SPI1 MOSI, TCA0 WO0 (alt), TCB2 WO, CCL LUT1 IN0.
3	PC1	bidirectional	General-purpose I/O port C pin 1 in the VDDIO2 power domain (MVIO). Alternate functions: USART1 RxD, SPI1 MISO, TCA0 WO1 (alt), TCB3 WO (alt), CCL LUT1 IN1.
4	PC2	bidirectional	General-purpose I/O port C pin 2 in the VDDIO2 power domain (MVIO). Alternate functions: TWI Fm+ capable, USART1 XCK, SPI1 SCK, TWI0 SDA (host/client, alt position), TCA0 WO2 (alt), EVSYS EVOUTC, CCL LUT1 IN2.
5	PC3	bidirectional	General-purpose I/O port C pin 3 in the VDDIO2 power domain (MVIO). Alternate functions: TWI Fm+ capable, USART1 XDIR, SPI1 SS, TWI0 SCL (host/client, alt position), TCA0 WO3 (alt), CCL LUT1 OUT.
6	VDDIO2	power_in	Multi-Voltage I/O (MVIO) supply input for PORTC. Independent 1.8-5.5 V supply that sets the digital I/O levels for PC0-PC3 on this device. Requires local decoupling (typ. 1 µF + 100 nF) referenced to the nearest GND pin.
7	PD1	bidirectional	General-purpose I/O port D pin 1 in the AVDD power domain. Analog function: ADC0 AIN1, OPAMP0 INP, ZCD0 ZCIN. Alternate digital functions: TCA0 WO1 (alt), CCL LUT2 IN1.
8	PD2	bidirectional	General-purpose I/O port D pin 2 in the AVDD power domain. Analog function: ADC0 AIN2, AC0/AC1/AC2 AINP0, OPAMP0 OUT (op-amp 0 output). Alternate digital functions: TCA0 WO2 (alt), EVSYS EVOUTD, CCL LUT2 IN2.
9	PD3	bidirectional	General-purpose I/O port D pin 3 in the AVDD power domain. Analog function: ADC0 AIN3, AC0 AINN0, AC1 AINP1, OPAMP0 INN. Alternate digital functions: TCA0 WO3 (alt), CCL LUT2 OUT.
10	PD4	bidirectional	General-purpose I/O port D pin 4 in the AVDD power domain. Analog function: ADC0 AIN4, AC1 AINP2, AC2 AINP1, OPAMP1 INP. Alternate digital functions: TCA0 WO4 (alt).
11	PD5	bidirectional	General-purpose I/O port D pin 5 in the AVDD power domain. Analog function: ADC0 AIN5, AC1 AINN0, OPAMP1 OUT (op-amp 1 output). Alternate digital functions: TCA0 WO5 (alt).
12	PD6	bidirectional	General-purpose I/O port D pin 6 in the AVDD power domain. Analog function: ADC0 AIN6, AC0/AC1/AC2 AINP3, DAC0 OUT (10-bit DAC output). Alternate digital function: CCL LUT2 OUT (alt).
13	PD7	bidirectional	General-purpose I/O port D pin 7 in the AVDD power domain. Analog function: VREFA (external analog reference input for ADC/DAC), ADC0 AIN7, AC0/AC1 AINN2, AC2 AINN0/AINN2, OPAMP1 INN. Alternate digital function: EVSYS EVOUTD (alt).
14	AVDD	power_in	Analog supply pin (1.8-5.5 V). Internally connected to VDD on this device family, but must be externally tied to the same supply as VDD with a dedicated local decoupling capacitor (typ. 1 µF + 100 nF) to the nearest AGND pin.
15	GND	power_in	Analog ground return (AGND) for the AVDD domain. Must be tied to the board ground plane; provides the return path for the analog decoupling capacitor on AVDD.
16	PF0	bidirectional	General-purpose I/O port F pin 0 in the VDD power domain. Special function: XTAL32K1 (input for external 32.768 kHz crystal oscillator). Alternate functions: USART2 TxD, TCA0 WO0 (alt), TCD0 WOA (alt), CCL LUT3 IN0.
17	PF1	bidirectional	General-purpose I/O port F pin 1 in the VDD power domain. Special function: XTAL32K2 (feedback/output for external 32.768 kHz crystal oscillator). Alternate functions: USART2 RxD, TCA0 WO1 (alt), TCD0 WOB (alt), CCL LUT3 IN1.
18	PF6	input	External RESET input (active-low). Configurable via RSTPINCFG in the System Configuration fuses to act as either the dedicated RESET pin or an input-only PORTF pin. Internal pull-up is present; external pull-up not normally required. A logic-low level triggers a device Reset.
19	UPDI	bidirectional	Unified Program and Debug Interface - dedicated single-wire pin for programming and debugging the device. Half-duplex UART-like protocol; connect through a series resistor to the programmer's UPDI line. Also usable as GPIO after configuring the UPDI pin function.
20	VDD	power_in	Main digital supply input (1.8-5.5 V). Provides power to the CPU core, digital peripherals, and PORTA/PORTD/PORTF I/O. Requires local decoupling (typ. 1 µF + 100 nF) referenced to the adjacent GND pin.
21	GND	power_in	Digital ground return for VDD. Must be tied to the board ground plane; carries the return current for the VDD decoupling capacitor.
22	PA0	bidirectional	General-purpose I/O port A pin 0. Special functions: XTALHF1 (input for external high-frequency crystal oscillator), EXTCLK (external clock input). Alternate functions: USART0 TxD, TCA0 WO0, CCL LUT0 IN0.
23	PA1	bidirectional	General-purpose I/O port A pin 1. Special function: XTALHF2 (feedback/output for external high-frequency crystal oscillator). Alternate functions: USART0 RxD, TCA0 WO1, CCL LUT0 IN1.
24	PA2	bidirectional	General-purpose I/O port A pin 2. Fm+ (1 MHz) TWI capable. Alternate functions: USART0 XCK, TWI0 SDA (host/client), TCA0 WO2, TCB0 WO, EVSYS EVOUTA, CCL LUT0 IN2.
25	PA3	bidirectional	General-purpose I/O port A pin 3. Fm+ (1 MHz) TWI capable. Alternate functions: USART0 XDIR, TWI0 SCL (host/client), TCA0 WO3, TCB1 WO, CCL LUT0 OUT.
26	PA4	bidirectional	General-purpose I/O port A pin 4. Alternate functions: USART0 TxD (alt), SPI0 MOSI, TCA0 WO4, TCD0 WOA.
27	PA5	bidirectional	General-purpose I/O port A pin 5. Alternate functions: USART0 RxD (alt), SPI0 MISO, TCA0 WO5, TCD0 WOB.
28	PA6	bidirectional	General-purpose I/O port A pin 6. Alternate functions: USART0 XCK (alt), SPI0 SCK, TCD0 WOC, CCL LUT0 OUT (alt).

Key specifications

Parameter	Value
Manufacturer	Microchip Tech
Package	SSOP-28
Category	Embedded Processors & Controllers
Pins	28

Ordering variants

Same part, different packaging or reel option.

AVR32DB28-II/SO
AVR32DB28-IT-I/SO
AVR32DB28-IE/SO
AVR32DB28-IT-E/SO
AVR32DB28-II/SS
AVR32DB28-IT-I/SS
AVR32DB28-IE/SS
AVR32DB28-IT-E/SS
AVR32DB28-II/SP
AVR32DB28-IE/SP

CAD (KiCad official)

Symbol: AVR32DB28-I
Footprint: Package_SO:SSOP-28_5.3x10.2mm_P0.65mm
3D model: SSOP-28 (KiCad packages3D, STEP)

Provenance

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

Datasheet: Microchip Tech datasheet (None pp, sha256 adfeb5005d481e53, retrieved 2026-08-17, tier: lcsc)
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