TCA9539PWR 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	Interrupt open-drain output. Asserted low whenever an input port pin changes state. Connect to VCC through a pull-up resistor. IOL up to 6 mA (Tj <= 85 C).
2	A1	input	I2C hardware address input bit 1. Tie directly to VCC or GND to select one of four I2C addresses. VIH >= 0.7VCC; VIL <= 0.3VCC.
3	RESET	input	Active-low hardware reset input. Drive low to reset device to default register state. Tie to VCC through a pull-up resistor if unused.
4	P00	bidirectional	Port 0 GPIO bit 0. Push-pull I/O; configured as input at power-on. Latched high-current drive suitable for driving LEDs directly (IOL up to 25 mA at Tj <= 65 C).
5	P01	bidirectional	Port 0 GPIO bit 1. Push-pull I/O; input at power-on.
6	P02	bidirectional	Port 0 GPIO bit 2. Push-pull I/O; input at power-on.
7	P03	bidirectional	Port 0 GPIO bit 3. Push-pull I/O; input at power-on.
8	P04	bidirectional	Port 0 GPIO bit 4. Push-pull I/O; input at power-on.
9	P05	bidirectional	Port 0 GPIO bit 5. Push-pull I/O; input at power-on.
10	P06	bidirectional	Port 0 GPIO bit 6. Push-pull I/O; input at power-on.
11	P07	bidirectional	Port 0 GPIO bit 7. Push-pull I/O; input at power-on.
12	GND	power_in	Ground reference / device return.
13	P10	bidirectional	Port 1 GPIO bit 0. Push-pull I/O; input at power-on.
14	P11	bidirectional	Port 1 GPIO bit 1. Push-pull I/O; input at power-on.
15	P12	bidirectional	Port 1 GPIO bit 2. Push-pull I/O; input at power-on.
16	P13	bidirectional	Port 1 GPIO bit 3. Push-pull I/O; input at power-on.
17	P14	bidirectional	Port 1 GPIO bit 4. Push-pull I/O; input at power-on.
18	P15	bidirectional	Port 1 GPIO bit 5. Push-pull I/O; input at power-on.
19	P16	bidirectional	Port 1 GPIO bit 6. Push-pull I/O; input at power-on.
20	P17	bidirectional	Port 1 GPIO bit 7. Push-pull I/O; input at power-on.
21	A0	input	I2C hardware address input bit 0. Tie directly to VCC or GND to select I2C address.
22	SCL	input	I2C/SMBus serial clock input. Requires an external pull-up to VCC. Supports 100 kHz and 400 kHz operation; 5 V tolerant.
23	SDA	bidirectional	I2C/SMBus serial data line (open-drain). Requires an external pull-up to VCC. IOL up to 6 mA (Tj <= 85 C); 5 V tolerant.
24	VCC	power_in	Supply voltage input, 1.65 V to 5.5 V. Bypass locally with a decoupling capacitor to GND.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	TSSOP-24
Category	Interface
Pins	24

Ordering variants

Same part, different packaging or reel option.

TCA9539PWR
TCA9539PWRRTW
TCA9539PWRRTWR
TCA9539PWRRGE
TCA9539PWRRGER

CAD (KiCad official)

Symbol: TCA9539PWR
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
`tca9539pwr.step`	315 KB	You want the bare part, or you mark your own boards.
`tca9539pwr-etched.step`	3.0 MB	You want the part with `TCA9539PWR` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 754 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 dbd074d61fa90111, 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