NXP Semiconductors PCA9550D,118

Overview

The PCA9550D,118 from NXP Semiconductors is a 2-bit I²C-bus LED blinker IC with dual programmable blink rates (0.172 Hz to 44 Hz), 25 mA per output sink capability, and integrated oscillator-designed to offload LED timing control from the host MCU in embedded status-indication systems such as industrial HMIs, network equipment front panels, and USB peripheral power indicators.

For engineers reviewing the PCA9550D,118 datasheet, PCA9550D,118 pinout, PCA9550D,118 application, or PCA9550D,118 equivalent, this device delivers deterministic LED blinking with minimal I²C bus traffic, supports GPIO reuse of unused LED pins, operates across 2.3 V–5.5 V, and integrates noise filtering on SCL/SDA for robust SMBus compatibility in noisy industrial environments.

Technical Context

The PCA9550D,118 implements an internal oscillator driving two independent PWM channels (BLINK0 and BLINK1), each configurable via dedicated prescaler (PSC0/PSC1) and duty-cycle (PWM0/PWM1) registers. Its I²C slave address is fixed at 0xC0 (with A0 pin selecting LSB), and register access uses auto-increment mode for sequential writes.

Each open-drain LED output supports high-impedance, static ON/OFF, or blink-mode selection via the LED selector (LS0) register. The device includes Power-On Reset (VPOR = 1.4–2.2 V) and active-low hardware RESET with 6 ns minimum pulse width, ensuring reliable initialization in power-cycled systems.

Key Specifications

Pinout & Package

PCA9550D,118 is packaged in SO8 (SOT96-1), 8-pin plastic small outline package with 3.9 mm body width and standard 1.27 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED blinker applications.

Compared with PCA9552DP,118 and TLC59108IPWR, the PCA9550D,118 uniquely delivers dual autonomous blink rates in a minimal 2-output SO8 package-making it optimal for cost- and space-constrained designs where exactly two deterministic LED signals are required without MCU overhead.

Availability

PCA9550D,118 is available at Aetrix Electronics and suitable for industrial HMIs, network equipment front panels, and USB peripheral power indicators requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for PCA9550D,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 deep expertise in I²C peripheral integration and low-power mixed-signal design.

The PCA9550D,118 belongs to NXP's I²C-bus peripheral family designed specifically to reduce MCU firmware burden in human-interface and status-indication subsystems-emphasizing autonomous operation, robust bus immunity, and industrial-grade reliability.

FAQ

What is the primary function of the PCA9550D,118 in an embedded system?

The PCA9550D,118 serves as an autonomous 2-bit I²C LED blinker that relieves the host MCU from managing LED timing. It executes pre-programmed blink patterns (BLINK0 and BLINK1) independently using its internal oscillator, reducing I²C bus traffic and freeing MCU timer resources. This makes PCA9550D,118 ideal for status indication where deterministic, low-overhead visual feedback is required without firmware involvement.

How does the PCA9550D,118 handle power-on and hardware reset conditions?

Upon power application, PCA9550D,118 performs Power-On Reset (POR) when VDD reaches 1.4–2.2 V, initializing all registers to default values (outputs HIGH, LED off). An active-low RESET pin provides asynchronous reset with ≥6 ns pulse width; holding RESET LOW forces all outputs to their default high-impedance (LED off) state until RESET returns HIGH. Both mechanisms ensure predictable startup behavior critical for safety-aware applications.

Can unused LED pins on the PCA9550D,118 be repurposed as general-purpose I/Os?

Yes-LED0 and LED1 pins on PCA9550D,118 can function as bidirectional GPIOs when not assigned to blink modes. Set the LS0 register to '01' for high-impedance input (readable via INPUT register) or '00' for active-low output (driven LOW when selected). External pull-up resistors are required for output use, and DC current must remain within 25 mA per pin and 50 mA total package limits-exactly as specified for PCA9550D,118 operation.

What I²C address does the PCA9550D,118 use, and how is it configured?

The PCA9550D,118 uses a fixed 7-bit I²C slave address of 0x60 (0xC0 write, 0xC1 read), with the LSB determined by the A0 pin state. When A0 is tied LOW, the address is 0xC0; when A0 is HIGH, it becomes 0xC1. No internal pull-up exists on A0, so an external resistor must bias it definitively-enabling two PCA9550D,118 devices on the same I²C bus without address collision.

Does the PCA9550D,118 require external components to generate its blink timing?

No-the PCA9550D,118 contains a fully integrated oscillator with no external components required. Blink periods are set by writing values to PSC0/PSC1 registers (period = (PSCn + 1)/44 Hz), and duty cycles are controlled via PWM0/PWM1 registers (duty = (256 − PWMn)/256). This self-contained timing architecture eliminates crystals, capacitors, or resistors-reducing BOM cost and improving timing stability over temperature and voltage for PCA9550D,118 deployments.