Translates the two lines of an I2C or SMBus bus between a lower and a higher voltage domain, so a controller at 1.2 or 1.8 V talks to 3.3 or 5 V devices on the same open-drain bus. Each channel handles the bidirectional traffic automatically, VCCA and VCCB set the two sides, and an OE pin isolates the buses when low. It is the level-shifter to reach for when a modern low-voltage SoC must share an I2C bus with higher-voltage peripherals.

Pinout

Pin	Name	Type	Function
1	SDA_B	bidirectional	I²C/SMBus data line on the B-port side. Referenced to VCCB (2.3 V to 5.5 V). Open-drain with an internal 10-kΩ pullup to VCCB.
2	GND	power_in	Device ground reference (0 V).
3	VCCA	power_in	A-port supply voltage. Operating range 1.65 V ≤ VCCA ≤ 3.6 V and VCCA ≤ VCCB. Sets the logic reference level for the A-side I/Os and OE.
4	SDA_A	bidirectional	I²C/SMBus data line on the A-port side. Referenced to VCCA (1.65 V to 3.6 V). Open-drain with an internal 10-kΩ pullup to VCCA.
5	SCL_A	bidirectional	I²C/SMBus clock line on the A-port side. Referenced to VCCA (1.65 V to 3.6 V). Open-drain with an internal 10-kΩ pullup to VCCA.
6	OE	input	Output enable, active High. Pull OE low to place all SDA/SCL outputs in the high-impedance (3-state) mode. Referenced to VCCA; VCCA-tolerant and also 5.5-V tolerant. May be tied directly to VCCA.
7	VCCB	power_in	B-port supply voltage. Operating range 2.3 V ≤ VCCB ≤ 5.5 V. Sets the logic reference level for the B-side I/Os. Either VCCA or VCCB may be ramped first (no supply sequencing required).
8	SCL_B	bidirectional	I²C/SMBus clock line on the B-port side. Referenced to VCCB (2.3 V to 5.5 V). Open-drain with an internal 10-kΩ pullup to VCCB.

Key specifications

Parameter	Value
Type	Dual bidirectional I2C/SMBus level translator
A side	1.1-3.6 V
B side	1.65-5.5 V
Channels	2 (SDA, SCL)
Direction control	None (auto, open-drain)
Enable	OE isolates buses
Package	VSSOP-8

Ordering variants

Same part, different packaging or reel option.

TCA9406DCUR (VSSOP-8)
TCA9406YZPR (DSBGA-8)

CAD (KiCad official)

Symbol: Interface:TCA9406DC (KiCad official)
Footprint: Package_SO:VSSOP-8_2.3x2mm_P0.5mm
3D model: VSSOP-8 (KiCad packages3D, STEP)

Provenance

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

Datasheet: Texas Instruments datasheet (38 pp, sha256 fdb80d682fbacd5e, 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