NXP Semiconductors PCA9512ADP,118

Overview

PCA9512ADP,118 from NXP Semiconductors is a hot-swappable I²C-bus and SMBus bidirectional buffer with dual supply voltage support (2.7 V to 5.5 V), enabling 5 V ↔ 3.3 V level shifting while maintaining optimal noise margins. It features 1 V precharge on all SDA/SCL pins, hardware-controllable rise time accelerators (0.6 V threshold), and bus isolation for live card insertion in multipoint backplane systems such as cPCI and AdvancedTCA.

For engineers reviewing the PCA9512ADP,118 datasheet, PCA9512ADP,118 pinout, PCA9512ADP,118 application, or PCA9512ADP,118 equivalent, this device delivers verified hot-swap capability, deterministic stop-bit–triggered connection timing, bidirectional capacitance isolation, and ACC-pin–enabled rise time accelerator disable-critical for high-reliability embedded backplane designs requiring stable I²C signal integrity across voltage domains.

Technical Context

The PCA9512ADP,118 implements a dynamic offset-based bidirectional buffering architecture that isolates backplane and card-side bus capacitances while supporting clock stretching, multi-master arbitration, and full I²C Standard/Fast-mode (0–400 kHz) compliance. Its undervoltage lockout (UVLO) requires both VCC and VCC2 ≥ 2.5 V before initialization, and its 100 kΩ precharge resistors pull SDAn/SCLn to 1 V during power-up.

Connection activation is gated by detection of bus idle or STOP condition on SCLIN/SDAIN, preventing contention. The ACC pin directly controls all four rise time accelerators: logic HIGH (VCC2) enables 2 mA transient pull-up current per line; logic LOW disables acceleration and retains standard pull-down slew control-enabling optimization for lightly loaded buses without external resistor changes.

Key Specifications

Pinout & Package

TSSOP8 (SOT505-1) package: 3 mm body width, 0.65 mm pitch, 8-lead thin shrink small outline-optimized for space-constrained I/O card edge placement and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9511ADP,118 and PCA9517ADP,118, the PCA9512ADP,118 uniquely balances hardware-controllable acceleration, 1 V precharge, and TSSOP8 footprint-making it optimal for space-constrained, dynamically loaded industrial backplanes where deterministic hot-swap timing and voltage-domain interoperability are non-negotiable.

Availability

PCA9512ADP,118 is available at Aetrix Electronics and suitable for cPCI, AdvancedTCA, and VMEbus systems requiring stable component supply, long-term lifecycle continuity, and guaranteed hot-swap reliability in mission-critical embedded infrastructure.

Supply support for PCA9512ADP,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 leader specializing in secure connectivity solutions for automotive, industrial, and IoT applications-with over two decades of I²C interface IP development.

The PCA9512A family was designed specifically for high-availability modular computing architectures, addressing the signal integrity, level translation, and live-insertion challenges inherent in standards-based backplane systems like PICMG and AdvancedTCA.

FAQ

What is the purpose of the ACC pin on the PCA9512ADP,118?

The ACC pin on the PCA9512ADP,118 is a CMOS digital input that enables or disables the built-in 2 mA rise time accelerators on all four SDA/SCL lines. When driven to VCC2, it activates acceleration to meet 1.25 V/μs slew requirements; when pulled to GND, it disables acceleration-allowing use with weaker pull-ups in lightly loaded systems. This function is exclusive to the PCA9512ADP,118 and not present in PCA9511ADP,118.

Does the PCA9512ADP,118 support 5 V to 3.3 V level translation with bidirectional signal integrity?

Yes, the PCA9512ADP,118 supports true bidirectional 5 V ↔ 3.3 V level translation using separate VCC (backplane) and VCC2 (card) supplies. Its dynamic offset driver design ensures LOW-level propagation across domains while maintaining 0.7×VCC/VCC2 noise margins-verified to prevent false edge generation and support clock stretching without signal degradation.

How does the PCA9512ADP,118 prevent bus contention during hot insertion?

The PCA9512ADP,118 prevents bus contention by holding SDAOUT and SCLOUT in high-impedance state until a STOP condition or sustained bus idle is detected on SCLIN/SDAIN. During insertion, its 1 V precharge circuitry (via 100 kΩ resistors) minimizes inrush current, and connection only activates after valid bus quiescence-guaranteeing zero contention on live backplanes.

What is the maximum I²C clock frequency supported by the PCA9512ADP,118?

The PCA9512ADP,118 supports I²C clock frequencies up to 400 kHz, fully compliant with I²C Fast-mode and SMBus specifications. This rating holds across the full operating temperature range (−40 °C to +85 °C) and supply voltage range (2.7 V to 5.5 V), with rise/fall times maintained via integrated acceleration and controlled offset voltage.

Can the PCA9512ADP,118 be used in series with other PCA9512A devices?

Yes, the PCA9512ADP,118 can be connected in series with other PCA9512A devices due to its incremental offset driver design. However, total cumulative offset is limited to 0.150 V (at 10 kΩ pull-up), so NXP recommends no more than two buffers in series to avoid exceeding the 0.6 V rise-time accelerator threshold and causing false clock edges.