Diodes Incorporated PI6ULS5V9511AUEX

Overview

PI6ULS5V9511A from Diodes Incorporated is a hot-swappable bidirectional I²C/SMBus buffer IC designed for live insertion into powered backplanes. It isolates SDA/SCL bus capacitance between card and backplane sides, supports clock stretching and multi-master arbitration, operates from 2.7V to 5.5V, and delivers up to 400kHz data rates with built-in 1.1V pre-charge and rise-time acceleration on all I²C lines.

For engineers reviewing the PI6ULS5V9511A datasheet, PI6ULS5V9511A pinout, PI6ULS5V9511A application, or PI6ULS5V9511A equivalent, this device addresses critical timing integrity, bus contention avoidance, and ESD-hardened hot-swap reliability in modular server, telecom line-card, and industrial rack-mount systems requiring live field-replaceable unit (FRU) support.

Technical Context

The PI6ULS5V9511A implements dual-channel bidirectional buffering with independent SDA and SCL paths, each featuring active pre-charge (1.1V), dynamic offset voltage control (110–175mV), and transient pullup current (≥2mA) triggered at 0.6V input threshold. Its startup logic enforces bus-idle or STOP-condition detection before connection, preventing corruption during hot insertion.

It integrates an open-drain READY output synchronized to internal connection state, an active-HIGH ENABLE with 110µs enable time, and high-impedance SDA/SCL pins at VCC = 0V. The device fully complies with I²C Standard Mode (100kHz), Fast Mode (400kHz), and SMBus specifications while supporting clock stretching and arbitration synchronization without protocol modification.

Key Specifications

Pinout & Package

PI6ULS5V9511A is available in MSOP-8 (U), UDFN-8 (ZW), and SOIC-8 (W) packages. All variants share identical pinout and functionality.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C hot-swap buffer applications.

Compared with TCA9517PWR and PCA9515DP, the PI6ULS5V9511A uniquely combines 400kHz timing compliance, integrated READY signaling, and hardware-enforced hot-swap safety-making it the only option that eliminates software coordination overhead for live FRU replacement in mission-critical infrastructure.

Availability

PI6ULS5V9511A is available at Aetrix Electronics and suitable for telecom line cards, industrial rack-mount controllers, server FRU management, and medical equipment hot-swap modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for PI6ULS5V9511A 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability interface, power management, and signal integrity solutions for industrial, computing, and communications markets.

The PI6ULS5V9511A belongs to Diodes' Ultra-Low Skew (ULS) I²C buffer product line, engineered specifically for hot-pluggable modular systems where bus integrity during live insertion is non-negotiable.

FAQ

What is the purpose of the READY pin, and how should it be used in system design?

The READY pin is an open-drain output indicating whether the internal SDA/SCL channels are electrically connected (READY HIGH) or isolated (READY LOW). It goes HIGH only after ENABLE is asserted HIGH and the bus has been idle or issued a STOP condition. System designers must tie READY to a microcontroller GPIO with a 10kΩ pullup to VCC and gate downstream I²C transactions until READY asserts-ensuring no data is sent before the buffer completes its safe connection sequence.

Can PI6ULS5V9511A operate with different supply voltages on the backplane and card sides?

No-the PI6ULS5V9511A requires a single VCC supply (2.7V–5.5V) that powers both sides of the buffer. Its rise-time accelerators depend on VCC matching the external pullup voltage, and its pre-charge circuit references VCC. Using separate supplies would violate the 0.6V activation threshold and disable acceleration, leading to non-compliant rise times and potential I²C timeouts.

How does the 1.1V pre-charge function prevent bus corruption during hot insertion?

During insertion, the backplane SDA/SCL lines may be at logic HIGH (e.g., 3.3V) while the card-side lines float near 0V. Without pre-charge, connecting them causes large transient currents that distort bus waveforms and trigger false START/STOP conditions. The 1.1V pre-charge pulls both sides to a common intermediate voltage before connection, reducing peak current to <100µA and eliminating glitches that could halt I²C arbitration or corrupt EEPROM writes.

What is the maximum number of PI6ULS5V9511A buffers that can be cascaded in series on one I²C bus?

Diodes recommends no more than two PI6ULS5V9511A buffers in series. Each adds ~110–175mV dynamic offset voltage, and after three buffers, the cumulative offset risks exceeding the 0.6V rising-edge accelerator threshold-causing false clock edges during clock stretching. With light loading and VOL ≤ 0.1V at the master, four buffers may function marginally, but reliability degrades significantly above two due to timing uncertainty and noise susceptibility.