NXP Semiconductors PCA9512D,112

Overview

The PCA9512D,112 from NXP Semiconductors (formerly Philips) is a hot-swappable, bi-directional I²C and SMBus buffer IC designed for multi-point backplane systems requiring live card insertion/removal without bus corruption. It provides 3.3 V ↔ 5 V level shifting via dual supply pins (VCC/VCC2), supports 0–400 kHz operation, features ∆V/∆t rise-time accelerators with hardware disable (ACC pin), and maintains isolation between backplane and card bus capacitances.

For engineers reviewing the PCA9512D,112 datasheet, PCA9512D,112 pinout, PCA9512D,112 application, or PCA9512D,112 equivalent, key selection criteria include hot-swap sequencing logic, dynamic offset voltage (<150 mV), 1 V precharge on all SDA/SCL lines, under-voltage lockout behavior, and compatibility with I²C fast-mode and SMBus standards in cPCI/VME/AdvancedTCA architectures.

Technical Context

The PCA9512D,112 implements a stop-bit-and-bus-idle detection circuit that delays connection until both SDAIN and SCLIN are HIGH for ≥50 µs or a STOP condition is detected-preventing contention during hot insertion. Its dynamic offset driver architecture enables series/parallel cascading with other PCA9510/11/12/13/14 devices but excludes static-offset parts like PCA9515/16/17 B-side or PCA9518.

Connection logic uses 100 kΩ internal precharge resistors to pull SDA/SCL lines to 1 V at power-up; once enabled, it isolates input/output capacitance while performing level translation. The ACC pin disables all four rise-time accelerators (2 mA transient pull-up) when driven to GND, allowing optimization for lightly loaded buses.

Key Specifications

Pinout & Package

Package: SO8 (SOT96-1), 3.9 mm body width, plastic small outline - industry-standard footprint compatible with automated assembly and thermal management in dense backplane cards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9512D,112, PCA9517DP,118 offers superior multi-drop scalability but sacrifices hot-swap-specific precharge and ACC flexibility, while TCA9517PWR delivers identical functional behavior with improved ruggedness-making it ideal for harsh-environment upgrades without layout changes.

Availability

The PCA9512D,112 is available at Aetrix Electronics and suitable for cPCI, VME, and AdvancedTCA systems requiring stable component supply, hot-swap reliability, and mixed-voltage I²C interoperability.

Supply support for PCA9512D,112 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 leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep heritage in I²C protocol development and system-level interface ICs.

The PCA9512D,112 belongs to NXP's I²C bus buffer product line, engineered specifically for high-reliability hot-swap backplane architectures in telecom and industrial computing platforms.

FAQ

What is the minimum bus capacitance required for reliable PCA9512D,112 operation?

The PCA9512D,112 requires ≥47 pF for 5 V systems and ≥22 pF for 3.3 V systems to ensure proper start-up and idle detection. This minimum capacitance stabilizes the 1 V precharge circuit and prevents oscillation during initialization. If measured bus capacitance falls below these thresholds, a discrete capacitor to ground must be added per bus line-verified via signal integrity testing before deployment.

How does the ACC pin affect PCA9512D,112 rise-time acceleration behavior?

When ACC is driven to GND, the PCA9512D,112 disables all four ∆V/∆t rise-time accelerators (2 mA pull-up current), reverting to standard open-drain drive strength. When ACC is pulled to VCC2, accelerators activate automatically upon detecting >0.6 V on any SDA/SCL line. This hardware-selectable mode allows optimization for heavily loaded (enable) or lightly loaded (disable) buses without firmware intervention.

Can PCA9512D,112 be used in series with other I²C buffers?

Yes-the PCA9512D,112's dynamic offset driver architecture permits series connection with other PCA9510/11/12/13/14 devices, with maximum recommended cascade depth of two units. Each adds ≤150 mV offset; beyond two stages, cumulative offset risks violating I²C VOL specifications. It cannot interface with static-offset devices like PCA9515/16/17 B-side due to incompatible driver topology.

What happens if only one supply (VCC or VCC2) is powered on the PCA9512D,112?

If either VCC or VCC2 drops below 2.0 V, the PCA9512D,112 enters under-voltage lockout (UVLO): connection circuitry disables, rise-time accelerators turn off, and 1 V precharge deactivates. Both supplies must exceed 2.5 V to exit UVLO and begin initialization. During UVLO, SDA/SCL pins enter high-impedance state-ensuring no unintended bus loading or contention.

Does PCA9512D,112 support clock stretching and multi-master arbitration?

Yes-the PCA9512D,112 transparently passes clock stretching and multi-master arbitration signals between backplane and card buses. Its bidirectional buffering preserves SCL hold-time and SDA sampling windows per I²C specification, and its dynamic offset design accommodates bidirectional LOW-level propagation required for arbitration resolution without introducing timing skew.