Analog Devices Inc. LTC4310CDD-2#PBF

Overview

LTC4310CDD-2#PBF from Analog Devices (formerly Linear Technology) is a bidirectional I²C isolator IC designed to enable robust, hot-swappable communication across galvanically isolated I²C buses. It supports 400kHz operation, provides ±5kV HBM ESD protection, integrates rise time accelerators for heavily loaded buses, and features stuck bus recovery with automatic clock generation and STOP bit insertion. It is used in isolated power supply monitoring and PoE-powered device management.

For engineers reviewing the LTC4310CDD-2#PBF datasheet, LTC4310CDD-2#PBF pinout, LTC4310CDD-2#PBF application, or LTC4310CDD-2#PBF equivalent, key selection criteria include maximum SCL frequency (400kHz), isolation barrier interface (transformer or capacitor-coupled), thermal shutdown threshold (150°C), EN-controlled shutdown current (≤0.1µA), and READY open-drain status signaling.

Technical Context

The LTC4310CDD-2#PBF implements event-driven differential pulse transmission over TXP/TXN and RXP/RXN pins, using 1.25V pseudo-differential pulses with ≤35ns width and ≤3ns rise/fall times. Its logic detection circuitry distinguishes local bus activity from self-driven outputs, enabling seamless arbitration, clock stretching, and ACK/NACK propagation across isolation barriers.

It enforces controlled SDA/SCL rising edge rates of 2–6.9 V/µs (depending on VCC) and activates IBOOST (2–6mA) above 0.45•VCC to meet I²C rise time specs under high bus capacitance (up to 800pF). Stuck bus recovery initiates after 37ms low state, issuing up to sixteen SCL clocks and a STOP bit before releasing drivers.

Key Specifications

Pinout & Package

Package: 10-lead (3mm × 3mm) plastic DFN with exposed pad (Pin 11), rated for 0°C to 70°C ambient operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C isolation applications.

Compared with ISO1540DR and ADUM1250ARZ, the LTC4310CDD-2#PBF delivers full I²C protocol transparency at 400kHz, eliminates external buffer components, and embeds critical system-level functions-stuck bus recovery, READY handshake, and rise time acceleration-reducing BOM count and firmware overhead.

Availability

LTC4310CDD-2#PBF is available at Aetrix Electronics and suitable for isolated power management, hot-swappable server infrastructure, and Power-over-Ethernet endpoint design requiring stable component supply and long-term industrial lifecycle support.

Supply support for LTC4310CDD-2#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.

The LTC4310CDD-2#PBF belongs to Linear's Hot Swap™ and I²C isolation product line, engineered specifically for robust, protocol-transparent galvanic isolation in mission-critical power and communications infrastructure.

FAQ

What is the maximum I²C clock frequency supported by the LTC4310CDD-2#PBF?

The LTC4310CDD-2#PBF supports a maximum SCL clock frequency of 400kHz, as specified in its Electrical Characteristics table. This distinguishes it from the LTC4310-1 variant (100kHz) and enables compatibility with Fast-mode Plus I²C systems. The device maintains full protocol compliance-including clock stretching and arbitration-at this speed, provided bus rise times are maintained via proper pull-up resistor selection and rise time accelerator activation.

Does the LTC4310CDD-2#PBF require external pull-up resistors on SDA and SCL lines?

Yes, the LTC4310CDD-2#PBF requires external pull-up resistors on both SDA and SCL lines-typically connected to the local bus supply (≥VCC). The maximum allowable resistance depends on bus capacitance and target frequency: for 400kHz operation, Figure 3 in the datasheet specifies RBUS(MAX) ≈ 4.3kΩ at 3.3V with 40pF load. The device's rise time accelerators activate above 0.45•VCC to assist these resistors, but they do not eliminate the need for them.

How does the LTC4310CDD-2#PBF handle a stuck I²C bus condition?

The LTC4310CDD-2#PBF monitors SDA and SCL for low-state duration; if both remain low for 37ms, it disables its drivers, transmits a stuck-bus alert across the isolation barrier, then issues up to sixteen SCL clock pulses followed by a STOP bit. This autonomous recovery sequence occurs without host intervention and resets all connected slaves. The READY pin releases high during stuck-bus mode and reasserts low only after both buses achieve simultaneous STOP/idle.

Can the LTC4310CDD-2#PBF be used with capacitive isolation instead of transformers?

Yes, the LTC4310CDD-2#PBF supports capacitive isolation using ceramic coupling capacitors on TXP/TXN and RXP/RXN. The datasheet recommends CRXP/CRXN ≥ 47pF and ≥10× board trace parasitic capacitance (CPAR). Capacitive coupling is suitable for lower-voltage isolation (e.g., <500V) and simplifies layout versus transformer-based solutions, though transformer coupling remains preferred for >1500V applications like PoE or industrial AC/DC supplies.

What is the function of the READY pin on the LTC4310CDD-2#PBF?

The READY pin on the LTC4310CDD-2#PBF is an open-drain output that pulls low only when the device has successfully synchronized the local and remote I²C buses-i.e., after detecting simultaneous STOP bits or bus idle states on both sides. It signals to the host system that bidirectional communication is active and stable. During startup, thermal shutdown, EN-driven shutdown, or stuck-bus recovery, READY floats high, providing unambiguous link status without polling.