The LTC2874 from Linear Technology is an IO-Link master IC that combines a power and communications interface to four remote IO-Link devices (slaves). A rugged interface and rich feature set make the devices suitable for larger systems implementing IO-Link (IEC61131-9) in harsh, industrial environments. Managing four slaves per master IC, the LTC2874 reduces board space, design complexity and costs while increasing levels of reliability.
The LTC2874 provides automatic Wake-Up Request (WURQ) generation and an output supply current-boosting capability for slave start-up. The WURQ generator produces self-timed wake-up pulses of correct polarity, reducing demands on the microcontroller. Safety mechanisms manage multiport and repeat WURQs to prevent thermal overload and maintain error-free communication. The current-boosting pulse generator fully implements the start-up current pulse requirements added to the IO-Link v1.1.1 specification.
The LTC2874 has been designed to add robustness and reliability to the physical interface specified in the IO-Link standard. For example the onboard Hot Swap controller and external N-channel MOSFET in the power interface protect connected devices from inrush currents during start-up and fault conditions. Integrated ±50V blocking diodes in the data line interface protect against faults and high voltage excursions, making it well-suited for the harsh PLC environment driving cables up to 20m long. The data lines can withstand ±8kV HBM ESD without latchup or damage, while all other pins are protected to ±6kV HBM.
A SPI interface allows host configuration and monitoring of multiple parameters including input supply voltage, output power good status, and fault events. Programmable controls for Hot Swap current limit foldback, circuit breaker timers, noise suppression filters and current sinking add flexibility for communication and fault handling in various systems.
Other capabilities make the LTC2874 suitable for a variety of applications. An 8V to 30V operating range supports the legacy Standard I/O (SIO) mode and other industrial applications. Driver outputs can be paralleled to achieve 4× the drive capability required by IO-Link. Signaling pins are compatible with IEC 61131-2 type 2 and type 3 digital I/O. A cable-sensing feature ensures that power supply outputs turn on only after cables are connected, allowing hot-plugging without sparking, which might otherwise reduce connector lifetime.