NXP Semiconductors PCU9661B,118

Overview

PCU9661B,118 from NXP Semiconductors is an 8-bit parallel-bus–to–Ultra Fast-mode I²C-bus protocol converter and single-channel master controller. It delivers unidirectional data transfer up to 5 Mbit/s using push-pull UFm topology, features a 4352-byte serial buffer, supports up to 64 slave devices per sequence, and operates with 3.3 V parallel interface and configurable 3.0–5.5 V I/O supply (VDD(IO)). It is used in LED matrix control and entertainment systems requiring high-throughput, low-CPU-overhead I²C expansion.

For engineers reviewing the PCU9661B,118 datasheet, PCU9661B,118 pinout, PCU9661B,118 application, or PCU9661B,118 equivalent, key selection considerations include UFm channel timing control via REFRATE/SCLPER registers, trigger-synchronized frame looping, interrupt masking granularity (SDMSK/FLDMSK/FEMSK), and hardware reset behavior across CE/WR/RD timing sequences.

Technical Context

The PCU9661B,118 implements a dedicated UFm master channel with internal 12 MHz oscillator and 156 MHz PLL for precise clock generation-enabling programmable SCL period (SCLPER register) and frame refresh rate (REFRATE register). Its transaction execution model relies on auto-increment DATA/SLATABLE registers and pointer control via TRANSEL/TRANOFS, with status reporting at three levels: transaction (STATUS2_[n]), channel (CHSTATUS), and controller (CTRLSTATUS).

Error handling is deterministic: frame errors (FE) occur when sequence duration exceeds REFRATE or inter-trigger interval; sequence done (SD) and frame loop done (FLD) are latched status bits cleared only by reading CHSTATUS; buffer overflow (BE) triggers controller-level interrupt and requires channel reset. JTAG boundary scan (TCK/TMS/TDO/TDI/TRST) supports manufacturing test without functional impact.

Key Specifications

Pinout & Package

PCU9661B,118 is housed in a plastic LQFP48 package (7 × 7 × 1.4 mm, SOT313-2) with 48 leads. Power and ground pins are distributed across multiple locations for noise reduction and thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9665 and TCA9548A, PCU9661B,118 uniquely combines parallel-bus host interface, 5 Mbit/s UFm master capability, and 4352-byte buffering-making it the sole option for CPU-offloaded, high-throughput, event-triggered I²C expansion where timing determinism and slave scalability are critical.

Availability

PCU9661B,118 is available at Aetrix Electronics and suitable for LED matrix control, entertainment systems, and data-intensive I²C-bus transfers requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCU9661B,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 PCU9661B,118 belongs to NXP's advanced I²C-bus controller product line, designed specifically to offload high-volume serial communication from host processors in bandwidth-constrained embedded systems.

FAQ

What is the maximum UFm data rate supported by the PCU9661B,118?

The PCU9661B,118 supports a maximum unidirectional Ultra Fast-mode (UFm) data rate of 5 Mbit/s using its push-pull output drivers on USDA2 and USCL2. This rate is achieved without external pull-up resistors and is maintained across the full VDD(IO) range of 3.0 V to 5.5 V. The internal PLL ensures stable clock generation independent of host bus timing, making PCU9661B,118 suitable for time-critical LED and display applications where standard I²C modes fall short.

How does the PCU9661B,118 handle buffer overflow during sequence loading?

When the PCU9661B,118 buffer overflows during sequence loading, the BE (Buffer Error) bit in the CTRLSTATUS register is set to logic 1. If the BEMSK bit in CTRLINTMSK is cleared (0), the INT pin asserts active-low to signal the error. Recovery requires a channel reset-either via software (writing to CONTROL register) or hardware (RESET pin assertion). After reset, all configuration registers (SLATABLE, TRANCONFIG, DATA) and buffer contents must be reloaded before resuming operation. PCU9661B,118 does not auto-recover or truncate sequences on overflow.

Can the PCU9661B,118 operate with different supply voltages for core logic and I²C I/O?

Yes, the PCU9661B,118 uses separate supply domains: core logic and parallel interface operate from VDD (3.0–3.6 V), while I²C-bus I/O levels are referenced to VDD(IO) (3.0–5.5 V). This decoupling allows PCU9661B,118 to interface directly with 3.3 V microcontrollers and 5 V legacy I²C peripherals without external level shifters. VSS(IO) must be tied to system ground, and all VDD pins must be externally connected together per the layout guidelines in the datasheet.

What role does the TRIG input play in PCU9661B,118 frame synchronization?

The TRIG input on the PCU9661B,118 provides hardware-level synchronization for frame-based I²C transfers. When TE (Trigger Enable) is set in the CONTROL register, each valid edge (configurable via TP bit) on TRIG initiates a new sequence transmission-overriding the REFRATE timer. This enables precise alignment of I²C data bursts with external events such as video frame starts, encoder zero-crossings, or sensor sampling clocks. PCU9661B,118 guarantees deterministic latency between TRIG assertion and START condition generation.

Does the PCU9661B,118 support JTAG boundary scan, and how is it used?

Yes, the PCU9661B,118 includes a full IEEE 1149.1-compliant JTAG port (TCK, TMS, TDI, TDO, TRST) for boundary scan testing during PCB manufacturing. In normal operation, TMS must be held HIGH, TCK and TDI HIGH, and TRST LOW; TDO is left unconnected. During test, JTAG enables verification of solder joints, trace continuity, and interconnect integrity without powering the device functionally-critical for high-reliability industrial and automotive assemblies using PCU9661B,118.