TCA4311D - 2.7-5.5V Hot-Swappable I2C Buffer | TI
MPN: TCA4311D ✓ ActiveTCA4311D Overview
An I2C bus buffer is a signal-conditioning interface IC used to isolate two bus segments, extend usable topology, and support controlled card insertion or removal. In the device hierarchy, this function belongs to interface ICs and specifically to bidirectional bus buffers, repeaters, and accelerators. The TCA4311D supports both I2C and SMBus-style two-wire systems, where data and clock lines require buffering rather than unidirectional level translation.
Verified headline features include a 2.7 V to 5.5 V operating range, 400 kHz operation, bidirectional signal paths, hot-swappable bus isolation, an enable control, and an open-drain READY output. The READY output indicates that the backplane and card sides are connected together. When EN is high, normal operation resumes; setting EN low places the device into shutdown mode while the I2C bus is idle.
The I2C specification cited by Texas Instruments permits up to 400 pF maximum bus capacitance, which can constrain practical bus length. The SMBus specification does not impose that capacitance restriction, although connected-device impedances still limit how quickly the system can meet rise-time and fall-time requirements. Designers should therefore evaluate board capacitance, wiring, pull-ups, and connected-device loading rather than treating buffer insertion as a universal cure for bus-loading problems.
Typical uses include server and desktop backplanes, plug-in acquisition modules, industrial control cards, communications equipment, and embedded systems where a card connects to an always-powered bus. The buffer is placed between the backplane pins and card-side pins, preserving independent local behavior on each side. System designers should verify idle-bus shutdown sequencing and interpret READY correctly before enabling the card interface.
PCB layout should keep SDA and SCL routing compact, preserve the intended pull-up arrangement on each bus side, and provide the decoupling and grounding required by the manufacturer datasheet. Because the verified material does not expose complete electrical timing, current, capacitance, and pin-level limits in the supplied text, those values remain marked for data completion rather than being inferred.
This page combines verified manufacturer and distributor information with design guidance, replacement analysis, and practical procurement context. It also distinguishes true pin-compatible alternatives from packaging-only orderable variants, helping engineers make evidence-based interface decisions.
Drop-in alternatives for TCA4311D — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
No drop-in alternatives available for this product.
Request AlternativesTCA4311D Specifications
| Product Type | 2-bit bidirectional I2C/SMBus buffer |
| Supply Voltage Range | 2.7 V to 5.5 V |
| Maximum Bus Frequency | 400 kHz |
| Number of Buffered Bits | 2 bits |
| Signal Direction | Bidirectional |
| Supported Buses | I2C and SMBus |
| Hot-Swap Support | Yes, hot-swappable |
| Enable Control | EN pin; low enables shutdown mode |
| Connection Status Output | Open-drain READY output |
| Connected Buses When READY Is High | SDAIN to SDAOUT and SCLIN to SCLOUT |
| I2C Maximum Bus Capacitance | 400 pF |
| SMBus Capacitance Restriction | None specified by SMBus, subject to rise-time and fall-time limits |
| Package | 8-pin SOIC, 0.154 inch wide, 3.90 mm |
| Mounting Type | Surface mount |
TCA4311D 8-pin soic, 0.154 inch wide, 3.90 mm Pin Configuration Guide
Pin configuration for TCA4311D (8-pin soic, 0.154 inch wide, 3.90 mm package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for TCA4311D.
Refer to the datasheet for full pin configuration.
Typical Applications
TCA4311D is suitable for 6 applications: Server Backplane Card Isolation, Industrial Data-Acquisition Card, Hot-Pluggable Communication Module, Embedded System Expansion Backplane, Test and Measurement Instrumentation, Serviceable Consumer Electronics Module.
Server Backplane Card Isolation
The Texas Instruments TCA4311D fits between a server backplane and a pluggable card because it buffers the SDA and SCL paths at up to 400 kHz while supporting a controlled connection sequence. Its 2.7 V to 5.5 V operating range covers common server interface levels, and the open-drain READY output can report whether the card side is connected. Designers should use READY, EN, address isolation, and power-good sequencing together; the verified material does not claim that the buffer alone provides complete electrostatic protection or unlimited hot-plug safety.
Recommended
Industrial Data-Acquisition Card
TCA4311D is useful when an industrial acquisition module connects to a live controller through a two-wire bus. The 400 kHz capability provides a defined operating ceiling, while EN permits shutdown when the bus is idle and READY provides a connection-status indication. The system designer should preserve separate pull-up networks, minimize trace capacitance, and sequence card power before enabling communications. Because the I2C specification cited by TI limits bus capacitance to 400 pF, long harnesses require careful electrical validation.
Recommended
Hot-Pluggable Communication Module
The TCA4311D supports communication modules that must be inserted into or removed from an operating system. Its bidirectional buffering isolates the backplane-side and card-side connections, while EN and READY help the host determine when normal bus communication is permitted. The implementation must also address device addresses, power rails, pull-up ownership, and connector sequencing so that unpowered or newly inserted cards do not disturb the active bus. The verified manufacturer page specifically confirms hot-swappable operation and open-drain READY reporting.
Recommended
Embedded System Expansion Backplane
TCA4311D can divide an embedded two-wire bus into a controller-side segment and an expansion-card segment, helping each side retain its intended loading and pull-up arrangement. The 2.7 V to 5.5 V supply range supports common 3.3 V and 5 V logic environments, and the 400 kHz rating aligns with standard fast-mode I2C operation. Engineers should compare propagation delay and timing margins using the complete datasheet, and should avoid treating this interface buffer as a substitute for proper level shifting between incompatible voltage domains.
Recommended
Test and Measurement Instrumentation
TCA4311D can separate an instrument's persistent controller bus from the connection to a replaceable sensor or frontend card. The READY output supports connection-state supervision, while EN allows the buffer to enter shutdown mode while the bus is idle. At up to 400 kHz, the device is appropriate for control and configuration traffic rather than high-bandwidth streaming. Layout review should include pull-up placement, connector return paths, ground continuity, and capacitance to prevent slow edges or unintended bus loading.
Recommended
Serviceable Consumer Electronics Module
The TCA4311D suits a serviceable consumer product where an internal module must connect to a main board through I2C or SMBus without continuously tying both bus segments together. Bidirectional operation supports normal clock and data transfer, while hot-swap, EN, and READY features help organize insertion and shutdown. The system must still control power and address isolation. Any claim of in-stock availability or unit price should be checked on 2026-10-23 because the verified search results did not provide numeric XAIPART pricing.
Recommended
Recommended Products Summary
Engineering reference data for TCA4311D — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product |
|---|---|
| Package | 8-pin SOIC, 0.154 inch wide, 3.90 mm |
| Brand | Texas Instruments |
| Function | 2-bit bidirectional I2C/SMBus buffer |
| Supply Voltage Range | 2.7 V to 5.5 V |
| Maximum Bus Frequency | 400 kHz |
| Hot-Swap Support | Yes |
| Enable Control | EN pin |
| Status Indication | Open-drain READY output |
Key Differentiators
- Explicit hot-swap control (vs Generic fixed-bus I2C repeater)
- Two-wire bidirectional isolation (vs Single-direction logic level shifter)
- Common interface-voltage coverage (vs Fixed 3.3 V-only bus buffer)
Design Notes
Implement card insertion as an explicit state machine rather than enabling the buffer automatically. Use EN to request shutdown while the I2C bus is idle, wait for the system-defined settling interval, check READY, and only then permit normal communication. Power sequencing, address isolation, and pull-up ownership remain separate controls; the verified Texas Instruments material confirms EN and READY behavior but does not establish a universal connector-level hot-plug procedure.
Route SDA and SCL on the backplane and card sides as short, matched routes with a continuous ground reference. Keep pull-up networks close to the nodes they serve and avoid sharing them across disconnected bus segments. The I2C specification cited by Texas Instruments allows up to 400 pF bus capacitance, so trace, connector, device, and cable capacitance should be budgeted before adding cable length or a large adapter card.
Evaluate rise and fall times at every connector and powered-device boundary rather than relying only on the nominal 400 kHz capability. Determine pull-up values from the actual bus capacitance, leakage, sink-current limits, and required edge rate, then confirm that propagation delay and timing margins satisfy the slowest connected peripheral. The supplied data does not include the numerical propagation-delay limits, so those values must come from the manufacturer datasheet before timing sign-off.
Do not treat READY high as proof that every electrical hot-plug hazard has been solved. A correct design also coordinates power state, logic levels, connector polarity, device addressing, and bus recovery after incomplete insertion. Because READY is open drain, provide the required pull-up and account for its effect on system timing. Avoid placing the TCA4311D where downstream devices can back-power an unpowered card segment.
Compliance Information
The verified material does not explicitly state RoHS, REACH, lead-free, halogen-free, or conflict-mineral status for TCA4311D. AEC-Q100 is not applicable to this general-purpose interface IC because no automotive qualification was provided.
