NXP Semiconductors PCA9522DP,118

Overview

PCA9522DP,118 from NXP Semiconductors is a fast dual bidirectional I²C/SMBus bus buffer with hot insertion logic, designed for live backplane interconnect. It provides level translation between 1.8 V and 10 V bus domains, supports up to 400 kHz operation, features open-collector RDY signaling, and delivers 6 mA static pull-down capability on SCL/SDA lines.

For engineers reviewing the PCA9522DP,118 datasheet, PCA9522DP,118 pinout, PCA9522DP,118 application, or PCA9522DP,118 equivalent, this device is selected for high-reliability hot-plug I²C isolation in telecom backplanes, ATCA systems, and multi-voltage RAID controllers where bus corruption during live insertion must be prevented and voltage domain bridging is required.

Technical Context

The PCA9522DP,118 implements symmetrical bidirectional buffering using open-collector outputs with dynamic control-side arbitration based on real-time voltage comparison between card-side (SCLC/SDAC) and backplane-side (SCLB/SDAB) ports. Its hot insertion logic monitors under-voltage lockout (UVLO), precharges backplane ports to 0.92 V, and waits for STOP or IDLE conditions before enabling signal pass-through.

Enable (EN) operates as a level-shifted control input supporting 1.8 V–12 V drive voltages independent of VCC (2.7 V–5.5 V), while RDY provides open-collector ready indication with 1.1 µs disable-to-ready delay. Offset voltage remains tightly controlled at ≤200 mV (typ.) under 4 mA sink load, ensuring glitch-free transitions even during bus control handover.

Key Specifications

Pinout & Package

TSSOP8 package (SOT505-1): plastic thin shrink small outline, 8 leads, 3 mm body width, 0.65 mm pitch, lead-free and RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9515DP,118 and TCA9517DGKR, the PCA9522DP,118 uniquely supports 10 V bus translation and integrates full hot-insertion sequencing-including precharge, UVLO, and STOP/IDLE validation-making it the only option qualified for AdvancedTCA-compliant live FRU insertion where bus voltage exceeds 5.5 V.

Availability

PCA9522DP,118 is available at Aetrix Electronics and suitable for backplane interconnect, ATCA systems, RAID controller architectures, and desktop/portable system management requiring stable component supply and long-term industrial availability.

Supply support for PCA9522DP,118 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The PCA9522DP,118 belongs to NXP's I²C-bus interface portfolio, engineered specifically for robust hot-plug-capable bus extension in carrier-grade telecom and high-availability computing platforms.

FAQ

What is the maximum bus voltage supported by the PCA9522DP,118?

The PCA9522DP,118 supports a maximum bus voltage of 10 V on SCLB, SCLC, SDAB, and SDAC pins. This is explicitly specified in Table 4 (Characteristics) and Table 3 (Limiting Values) of the official NXP datasheet Rev. 1. The device is rated for 12 V absolute maximum on these pins, but operational bus voltage is limited to 10 V to ensure I²C-bus specification compliance and long-term reliability. This 10 V capability distinguishes it from alternatives like the TCA9517DGKR (5.5 V max).

Does the PCA9522DP,118 require external pull-up resistors on the I²C bus lines?

Yes, the PCA9522DP,118 requires external pull-up resistors on all four buffered lines (SCLC, SDAC, SCLB, SDAB), as it uses open-collector outputs. The datasheet specifies a 6 mA static pull-down capability, which determines minimum pull-up values-for example, a 1 kΩ resistor yields ~1 V drop at 1 mA, suitable for 3.3 V buses. RDY also requires an external pull-up. No internal pull-ups are present; omission results in non-functional bus operation.

How does the hot insertion logic in the PCA9522DP,118 prevent bus corruption?

The PCA9522DP,118 prevents bus corruption during hot insertion through three coordinated actions: (1) Under-Voltage Lockout (UVLO) holds all ports inactive until VCC exceeds 2.2 V; (2) Precharge circuitry raises SCLB/SDAB voltages to ~0.92 V before enable; (3) After power stabilization, it waits for a STOP or full bus IDLE condition (≥75 µs) before connecting card and backplane sides. This sequence eliminates voltage transients and ensures no partial transactions propagate across the buffer.

Can the PCA9522DP,118 translate between 1.8 V and 5 V I²C domains?

Yes, the PCA9522DP,118 is explicitly designed for bidirectional level translation between 1.8 V and 5 V I²C domains-and beyond, up to 10 V. Its architecture allows SCLC/SDAC to operate at 1.8 V (card side) while SCLB/SDAB interface a 5 V backplane, with no external components required. This is confirmed in Section 1 (General description), Figure 8 (backplane application), and Table 4 (Vbus = 10 V). The enable pin (EN) further supports level-shifted control, e.g., a 1.8 V microcontroller enabling a 5 V-buffered bus.

What is the function of the RDY pin on the PCA9522DP,118?

The RDY pin on the PCA9522DP,118 is an open-collector ready indicator that signals when the buffer has completed its start-up sequence and is safely connected. It is internally switched OFF (high-impedance) once UVLO exits, precharge completes, and a valid STOP or IDLE condition is detected-allowing an external pull-up resistor to pull RDY HIGH. The datasheet specifies a 95 µs delay from EN HIGH to RDY deactivation, providing a deterministic hardware handshake for system controllers to synchronize with buffer readiness.