NXP Semiconductors PCA9661B,118

Overview

PCA9661B,118 from NXP Semiconductors is an 8-bit parallel-bus–to–I²C-bus protocol converter and single-channel Fast-mode Plus (Fm+) I²C master controller. It operates at up to 1 Mbit/s, features a 4352-byte data buffer, supports up to 64 slave devices per sequence, and integrates an internal 12 MHz oscillator with ±1 % accuracy. It serves as a high-throughput serial interface bridge for microcontrollers lacking native I²C capability in LED matrix control and entertainment systems.

For engineers reviewing the PCA9661B,118 datasheet, PCA9661B,118 pinout, PCA9661B,118 application, or PCA9661B,118 equivalent, key selection considerations include its 48-pin LQFP package, Fm+ open-drain I²C I/O voltage range (3.0 V to 5.5 V), 3.3 V parallel bus interface, sequence looping with external trigger synchronization, and three-level reset architecture (hardware, global software, channel software).

Technical Context

The PCA9661B,118 implements a dedicated parallel-to-serial conversion engine with autonomous sequence execution: it loads transaction sets (reads/writes to up to 64 slaves) into its 4352-byte buffer, then executes them without CPU intervention using RESTART/STOP framing. Its internal 12 MHz oscillator and 156 MHz PLL generate all timing signals-including SCL clock, interval timer for looped refresh, and JTAG test clocks-eliminating external timing components.

Error handling occurs at three layers: transaction-level (via STATUS0_[n] registers reporting RSN/WSN/WDN), channel-level (CHSTATUS flags like DAE, CLE), and controller-level (CTRLSTATUS). Interrupts are maskable per level, and the INT pin is open-drain active-low with configurable polarity and trigger enable via CONTROL register bits TE and TP.

Key Specifications

Pinout & Package

PCA9661B,118 is housed in a plastic low-profile quad flat package (LQFP48) measuring 7 mm × 7 mm × 1.4 mm, with exposed thermal pad (SOT313-2). All VDD pins (7, 30, 40, 44, 48) must be tied together externally; all VSS pins (8, 29, 35, 39, 43, 47) require common ground connection. VDD(IO) (pin 24) and VSS(IO) (pin 23) supply I²C-bus logic levels independently.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9665,118, the PCA9661B,118 offers lower cost and power for single-bus systems but lacks channel redundancy; versus PCA9685PW,118, it provides true parallel-to-I²C protocol conversion with Fm+ speed and large buffering-making it suitable for data-intensive bridging rather than fixed-function PWM output.

Availability

PCA9661B,118 is available at Aetrix Electronics and suitable for LED matrix control, entertainment systems, and data-intensive sensor aggregation requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCA9661B,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 PCA9661B,118 belongs to NXP's I²C-bus controller product line, engineered to offload high-volume serial communication from resource-constrained hosts-enabling deterministic, low-CPU-overhead peripheral interfacing in timing-critical embedded systems.

FAQ

What is the maximum I²C-bus data rate supported by the PCA9661B,118?

The PCA9661B,118 supports Fast-mode Plus (Fm+) operation at up to 1 Mbit/s. This is achieved using open-drain I²C I/Os (SCL0/SDA0) rated for 30 mA sink current, enabling robust high-speed communication with standard Fm+ slaves. The internal PLL ensures precise clock generation without external components, maintaining timing integrity across temperature and voltage variations within the 3.0 V to 5.5 V VDD(IO) range.

How does the PCA9661B,118 handle I²C transaction errors such as slave NACK?

The PCA9661B,118 reports slave NACK conditions at three levels: RSN (Read Slave NACK) and WSN (Write Slave NACK) bits in STATUS0_[n] registers flag per-transaction failures; CHSTATUS indicates channel-level bus errors (e.g., DAE for SDA stuck low); and CTRLSTATUS captures controller-wide issues. When unmasked, these trigger the open-drain INT pin. The host can configure error handling via INTMSK and REMSK/WEMSK bits to either halt the sequence or skip the failed transaction and continue.

Can the PCA9661B,118 operate with different voltage domains for its parallel interface and I²C-bus I/Os?

Yes. The PCA9661B,118 separates power domains: its parallel bus interface (A0–A7, D0–D7, CE, WR, RD) operates at 3.3 V (VDD = 3.0–3.6 V), while its I²C-bus I/Os (SCL0/SDA0) are referenced to VDD(IO), which accepts 3.0 V to 5.5 V. This allows direct interfacing with 3.3 V microcontrollers and 5 V I²C peripherals without external level shifters-reducing component count and signal integrity risks in mixed-voltage designs.

What is the purpose of the TRIG input on the PCA9661B,118 and how is it configured?

The TRIG input on the PCA9661B,118 provides hardware-synchronized frame initiation: when enabled (TE = 1 in CONTROL register), each valid edge (rising or falling, set by TP bit) on TRIG starts a new I²C sequence from the buffer. This enables precise alignment of I²C data transfers with external events-such as video frame sync pulses or motor encoder zero-crossings-ensuring deterministic timing critical for real-time control loops and display updates.

Does the PCA9661B,118 require an external crystal or oscillator?

No. The PCA9661B,118 integrates a factory-trimmed 12 MHz internal oscillator with ±1 % accuracy and a 156 MHz PLL, generating all required clocks for I²C timing, interval timers, and JTAG testing. This eliminates the need for external crystals, capacitors, or clock sources-reducing BOM cost, PCB area, and design validation effort while improving reliability in vibration-prone or space-constrained applications.