PCA9555PWR from Texas Instruments, in a TSSOP-24. 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	INT	output	Active-low, open-drain interrupt output. Asserted on any input-port state change; connect to VCC through a pull-up resistor.
2	A1	input	I2C hardware address input bit 1. Tie directly to VCC or GND to set the device's I2C slave address.
3	A2	input	I2C hardware address input bit 2. Tie directly to VCC or GND to set the device's I2C slave address.
4	P00	bidirectional	Port 0 bit 0, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
5	P01	bidirectional	Port 0 bit 1, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
6	P02	bidirectional	Port 0 bit 2, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
7	P03	bidirectional	Port 0 bit 3, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
8	P04	bidirectional	Port 0 bit 4, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
9	P05	bidirectional	Port 0 bit 5, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
10	P06	bidirectional	Port 0 bit 6, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
11	P07	bidirectional	Port 0 bit 7, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
12	GND	power_in	Device ground return.
13	P10	bidirectional	Port 1 bit 0, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
14	P11	bidirectional	Port 1 bit 1, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
15	P12	bidirectional	Port 1 bit 2, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
16	P13	bidirectional	Port 1 bit 3, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
17	P14	bidirectional	Port 1 bit 4, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
18	P15	bidirectional	Port 1 bit 5, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
19	P16	bidirectional	Port 1 bit 6, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
20	P17	bidirectional	Port 1 bit 7, push-pull general-purpose I/O. IOL = 25 mA max sink, IOH = -10 mA max source. Defaults to input at power-on.
21	A0	input	I2C hardware address input bit 0. Tie directly to VCC or GND to set the device's I2C slave address.
22	SCL	input	I2C serial clock (400 kHz Fast-mode). Open-drain bus line; connect to VCC through a pull-up resistor.
23	SDA	bidirectional	I2C serial data (400 kHz Fast-mode). Open-drain bus line; connect to VCC through a pull-up resistor.
24	VCC	power_in	Supply voltage, 2.3 V to 5.5 V. Decouple to GND with a local bypass capacitor.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	TSSOP-24
Category	Comm/UART
Pins	24

Ordering variants

Same part, different packaging or reel option.

PCA9555PWR
PCA9555PWRDB
PCA9555PWRDBR
PCA9555PWRDBQ
PCA9555PWRDBQR
PCA9555PWRDGV
PCA9555PWRDGVR
PCA9555PWRDW
PCA9555PWRDWR
PCA9555PWRRGE
PCA9555PWRRGER

CAD (KiCad official)

Symbol: PCA9555PWR
Footprint: Package_SO:TSSOP-24_4.4x7.8mm_P0.65mm
3D model: TSSOP-24 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`pca9555pwr.step`	315 KB	You want the bare part, or you mark your own boards.
`pca9555pwr-etched.step`	3.0 MB	You want the part with `PCA9555PWR` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 750 faces against 387 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: Texas Instruments datasheet (49 pp, sha256 9b5cc24c3c9e286a, 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