TCA9406DCTR - 2-Bit Bidirectional I2C/SMBus Level Translator | TI
MPN: TCA9406DCTR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.24 | $1.24 |
| 10 | $1.11 | $11.10 |
| 100 | $0.98 | $98.00 |
| 500 | $0.86 | $430.00 |
| 1,000 | $0.74 | $740.00 |
TCA9406DCTR Overview
A voltage-level translator is an interface IC that bridges digital signal domains operating at different supply rails, allowing a microcontroller running at 1.8 V or 3.3 V to safely communicate with peripheral devices on a 5 V bus. Within the signal-chain hierarchy, level translators sit between logic ICs and physical bus lines and are essential members of the I2C/SMBus interface family, where open-drain bidirectional lines cannot be shifted with simple resistor dividers.
Key differentiating specifications include true bidirectional operation without a direction pin, support for the 1-MHz Fast-mode Plus I2C class of operation with data rates up to 24 Mbps in general-purpose push-pull use, and 8 kV human-body-model ESD robustness on the bus pins. The dedicated OE input lets the system place both channels in the high-impedance state during power sequencing or bus reconfiguration, preventing bus contention and back-powering through partial-rail conditions.
Architecturally, the TCA9406 integrates an internal boost/reference generator on the B side so that only two supply pins (VCCA and VCCB) and a minimal external component count are required - no external pull-up resistors to a reference rail are needed, unlike pass-gate translators such as the TI PCA9306. This integrated drive makes rise and fall times far less dependent on bus loading, which matters when the bus runs at 400 kHz or 1 MHz with cable or connector capacitance.
Typical applications include I2C sensor interfacing in battery-powered products, SMBus communication between 3.3 V management controllers and 5 V power-supply modules, and level shifting between low-voltage MCUs and 5 V EEPROMs or RTCs. It fits anywhere a 1.8 V, 2.5 V, or 3.3 V host must drive a 5 V peripheral bus reliably.
A key design consideration: the OE pin should be driven by a supply-rail supervisor or held low until both VCCA and VCCB are stable, since enabling the translator before the higher rail is up can momentarily clamp the bus.
This page synthesizes distributor pricing and stock, drop-in alternative analysis against the NXP PCA9306, pinout data, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for TCA9406DCTR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
TCA9406DCTG4
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PCA9306DC
✅ Drop-In📋 Reference alternative (not in catalog)
TCA9406DCTR Maximum Ratings & Electrical Characteristics
| Function | 2-bit bidirectional voltage-level translator |
| Bus Interface | I2C bus and SMBus |
| Channels | 2 (bidirectional, 1 circuit) |
| VCCA Supply Range (A-side) | 1.65 V to 3.6 V |
| VCCB Supply Range (B-side) | 2.3 V to 5.5 V |
| Max Data Rate | 24 Mbps |
| I2C Speed Class | 1 MHz (Fast-mode Plus compatible) |
| Output Enable (OE) | Yes, high-impedance when disabled |
| ESD Protection | 8 kV HBM |
| Package | SM8 / SSOP-8 (DCT) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C |
| MSL Level | MSL 1 (260C unlimited) |
| RoHS Status | Compliant |
| Typical Rails Supported | 1.8 V, 2.5 V, 3.3 V, 5 V |
TCA9406DCTR Pin Configuration
| Pin 1 | VCCA — A-side supply voltage, 1.65 V to 3.6 V |
| Pin 2 | A1 — A-side bidirectional data channel 1 (referenced to VCCA) |
| Pin 3 | A2 — A-side bidirectional data channel 2 (referenced to VCCA) |
| Pin 4 | GND — Ground reference |
| Pin 5 | OE — Output enable; high = channels active, low = both channels high-impedance |
| Pin 6 | B2 — B-side bidirectional data channel 2 (referenced to VCCB) |
| Pin 7 | B1 — B-side bidirectional data channel 1 (referenced to VCCB) |
| Pin 8 | VCCB — B-side supply voltage, 2.3 V to 5.5 V |
Typical Applications
TCA9406DCTR is suitable for 6 applications: I2C Sensor Interfacing in Battery-Powered Products, SMBus Power-Supply Management, 5 V EEPROM and RTC interfacing for 3.3 V MCUs, Consumer Electronics Peripheral Ports, Automotive and Industrial Diagnostic Buses, Test and Measurement Instrument Motherboards.
I2C Sensor Interfacing in Battery-Powered Products
Battery-powered wearables and IoT nodes increasingly use 1.8 V MCUs for power savings, while many popular sensors (RTC, humidity, pressure) remain 3.3 V or 5 V devices. The TCA9406DCTR bridges the 1.8 V controller domain to a 3.3 V sensor bus using its 1.65-3.6 V VCCA and 2.3-5.5 V VCCB ranges, so a single translator covers any rail pairing. Because it integrates the reference generation, no external pull-ups to an intermediate rail are needed, saving BOM area on dense wearables. The OE input lets the MCU disconnect the bus entirely during sleep, and the translator's low standby behavior preserves battery life. At 400 kHz Fast-mode, the active drive keeps rise times well within the 300 ns I2C limit even with cable capacitance.
Recommended
SMBus Power-Supply Management
Server and telecom backplanes commonly run the PMBus/SMBus management link at 3.3 V while many hot-swap power modules and battery packs expose a 5 V SMBus port. The TCA9406DCTR handles this translation directly: its 8 kV HBM ESD rating on the bus pins provides robustness for hot-insert environments, and the OE pin lets the management controller isolate the bus during module insertion or power-sequence faults, preventing bus latch-up. The 1 MHz speed class exceeds the 100 kHz SMBus requirement with wide margin, so heavy backplane capacitance does not violate the 1 us SMBus rise-time limit. Active output drive means designers avoid the trial-and-error pull-up resistor tuning that pass-gate translators require on long backplane traces.
Recommended
5 V EEPROM and RTC interfacing for 3.3 V MCUs
Industrial control boards frequently retain 5 V EEPROMs, real-time clocks, and supervisory devices for legacy compatibility while the main MCU runs at 3.3 V. The TCA9406DCTR translates the two-wire bus between the 3.3 V VCCA domain and the 5 V VCCB domain transparently and bidirectionally - no direction pin is needed, which matters because I2C lines reverse direction every byte. Its 24 Mbps general-purpose capability also covers faster proprietary two-wire links if the board uses them. The high-impedance OE state allows in-system programming of the EEPROM without bus contention from the MCU. Designers should connect OE to a supervisor or MCU GPIO held low during power-up so the bus stays released until both rails are stable.
Recommended
Consumer Electronics Peripheral Ports
Set-top boxes, smart speakers, and TVs often use a 1.8 V or 3.3 V SoC while accessory connectors, touch controllers, or EDID EEPROMs on HDMI/VGA ports sit on 5 V rails. The TCA9406DCTR provides hot-plug-safe translation: the 8 kV HBM ESD rating withstands connector transients, and driving OE low during cable events isolates the SoC from undefined bus states. Because translation is fully bidirectional with no direction control, EDID reads over DDC (an I2C variant) work without firmware coordination. The small SM8/SSOP-8 footprint fits dense consumer layouts, and MSL 1 rating simplifies reflow handling in high-volume assembly. Active drive keeps DDC rise times compliant despite cable capacitance of 100 pF or more.
Recommended
Automotive and Industrial Diagnostic Buses
Automotive body controllers and industrial drives frequently mix a 3.3 V main MCU with 5 V sensors, actuators, and service-connector diagnostics. The TCA9406DCTR's -40C to +85C operating range covers most industrial and under-dash automotive ambient requirements, and its two channels suffice for standard two-wire diagnostic or sensor buses. The OE pin enables the service tool to take ownership of the bus: the module holds OE low by default and asserts it only when a diagnostic session starts, guaranteeing no contention. Its 1 MHz capability supports accelerated diagnostic protocols, and active drive maintains signal integrity across the wiring harness capacitance typical of vehicle and machine installations, which passive translators struggle to meet.
Recommended
Test and Measurement Instrument Motherboards
Bench instruments and data-acquisition systems combine low-voltage FPGA/DSP management logic with 5 V front-end modules, calibration EEPROMs, and fan controllers on shared two-wire buses. The TCA9406DCTR translates these domains while its high-impedance OE state lets the system segment the bus for isolated module calibration - a common requirement in production test. The 24 Mbps ceiling also supports general-purpose push-pull clock/data shifting where a front-end uses a two-wire synchronous link instead of open-drain I2C. With only two supply pins and no external reference components, the translator integrates cleanly into card-based architectures, and the SM8 package's straightforward two-row pinout eases automated optical inspection of solder joints across long production runs.
Recommended
Recommended Products Summary
Engineering reference data for TCA9406DCTR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TCA9406DCTG4 | PCA9306DC |
|---|---|---|---|
| Package | SM8 / SSOP-8 (DCT) | SM8 / SSOP-8 - same | SM8 / SSOP-8 - same |
| Brand | Texas Instruments | Texas Instruments | NXP Semiconductors |
| Channels / Bits | 2 bidirectional | 2 bidirectional | 2 bidirectional |
| VCCA Range | 1.65 V to 3.6 V | 1.65 V to 3.6 V | 1.0 V to 3.6 V (VREF1) |
| VCCB Range | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 1.8 V to 5.5 V (VREF2) |
| Output Enable (OE) | Dedicated OE pin | Dedicated OE pin | No OE; enable via VREF2/EN |
| Max Data Rate | 24 Mbps (1 MHz I2C class) | 24 Mbps (1 MHz I2C class) | Pass-gate; rise time set by external pull-ups |
| External Components | None (integrated reference) | None | External pull-up resistors to VREF2 required |
Key Differentiators
- Integrated reference generation - no external pull-ups (vs PCA9306DC)
- Dedicated OE pin for bus isolation (vs PCA9306DC)
- 8 kV HBM ESD robustness on bus pins (vs PCA9306DC)
- Trade-off: active drive consumes more supply current (vs PCA9306DC)
Design Notes
Power sequencing is the dominant failure mode for this translator. Hold OE low until both VCCA (1.65-3.6 V) and VCCB (2.3-5.5 V) are within regulation; otherwise the device can clamp the I2C lines low while either rail ramps, stalling other masters on a shared bus. Implement OE with an MCU GPIO or a small voltage supervisor on the lower rail. Note the datasheet constraint that VCCA must be at or below the referenced B-side level per the device's rail-order requirements - check the VCCA/VCCB relationship section before applying rails in arbitrary order.
Place 0.1 uF ceramic decoupling capacitors within 2 mm of both VCCA (pin 1) and VCCB (pin 8) to their respective grounds. Keep the A-side and B-side traces short and route them away from switching-regulator nodes; although the translator's active drive is more tolerant of capacitance than pass-gate parts, excessive stub length still degrades edge rates at 1 MHz. Because the OE pin is a control input, give it a defined pull-down (10k to GND) so the bus defaults to isolated during MCU reset or connector hot-plug.
Do not substitute the NXP PCA9306DC without a schematic change: its pin 5 is not an OE and it requires external 4.7k-10k pull-up resistors to a VREF2 rail, so a footprint-compatible swap will not function. Also avoid connecting push-pull 5 V logic directly to the A pins - the A side is specified only up to 3.6 V. Estimated worst-case dissipation is negligible (sub-10 mW), so thermal design is not a concern; focus engineering effort on rail sequencing and bus loading instead.
Compliance Information
RoHS Compliant and MSL Level 1 (260C unlimited) per PartGenie distributor parametric data. REACH, halogen-free, and conflict-minerals status not stated in provided data - confirm via TI compliance portal.
