NXP Semiconductors PCA9550D,112

Overview

PCA9550D,112 from NXP Semiconductors is a 2-bit I²C-bus LED blinker IC with dual programmable blink rates (0.172–44 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 power supply status modules.

For engineers reviewing the PCA9550D,112 datasheet, PCA9550D,112 pinout, PCA9550D,112 application, or PCA9550D,112 equivalent, this device delivers deterministic LED blinking with minimal I²C traffic, supports GPIO reuse of unused LED pins, operates across 2.3–5.5 V, and integrates noise filtering on SCL/SDA for robust bus communication in electrically noisy environments.

Technical Context

The PCA9550D,112 implements an internal RC oscillator driving two independent PWM channels (BLINK0 and BLINK1), each with dedicated prescaler (PSC0/PSC1) and duty-cycle (PWM0/PWM1) registers. Blink period resolution is defined by (PSCn + 1)/44 Hz, enabling precise timing without external components.

Its I²C interface complies with SMBus specifications, includes active-low RESET and Power-On Reset (POR), and features hardware address pin A0 for dual-device bus addressing. All registers-including INPUT, LS0 (LED selector), and control registers-are accessed via standard I²C write/read sequences with auto-increment support.

Key Specifications

Pinout & Package

PCA9550D,112 is supplied in SO8 (SOT96-1) package: plastic small outline, 8 leads, 3.9 mm body width, surface-mount compatible.

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,112 uniquely balances minimal pin count, zero-software blink autonomy, and industrial-grade robustness-making it optimal for cost-sensitive, resource-constrained dual-LED status systems where deterministic timing is mandatory.

Availability

PCA9550D,112 is available at Aetrix Electronics and suitable for industrial HMIs, network equipment front panels, and power supply monitoring units requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for PCA9550D,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 expertise in mixed-signal and interface IC design.

The PCA9550D,112 belongs to NXP's I²C-bus peripheral family, engineered specifically to reduce MCU firmware load in embedded status-indication subsystems through autonomous, low-power LED timing control.

FAQ

What is the primary function of the PCA9550D,112 in an embedded system?

The PCA9550D,112 serves as an autonomous I²C-controlled LED blinker that relieves the host MCU from managing LED timing. It executes two independent blink patterns (BLINK0 and BLINK1) using internal registers and an integrated oscillator-enabling consistent, low-overhead visual status indication without consuming MCU timer resources or generating excessive I²C traffic. This makes PCA9550D,112 ideal for resource-constrained designs.

Can unused LED outputs on the PCA9550D,112 be repurposed as general-purpose I/Os?

Yes. When configured via the LS0 (LED selector) register to high-impedance mode (01), LED0 or LED1 pins become readable inputs; when driven LOW via LS0 (00), they function as open-drain outputs usable with external pull-ups. The INPUT register reflects actual pin states, and the PCA9550D,112 supports full read-modify-write access-allowing true GPIO expansion without adding discrete buffers or shift registers.

How does the PCA9550D,112 handle power-on and hardware reset conditions?

The PCA9550D,112 incorporates both Power-On Reset (POR) and active-low hardware RESET. POR initializes all registers to default values (outputs HIGH/off) once VDD reaches VPOR (1.4–2.2 V). The RESET pin forces identical initialization when held LOW for ≥6 ns. Both mechanisms ensure predictable startup and recovery-critical for fail-safe LED behavior in industrial systems. PCA9550D,112 requires no external reset circuitry.

What are the I²C address options for the PCA9550D,112?

The PCA9550D,112 uses a fixed 7-bit base address of 0x60, with the LSB determined by the A0 pin state: A0 = LOW → 0x60, A0 = HIGH → 0x61. No internal pull-up exists on A0, so it must be externally biased. This allows two PCA9550D,112 devices on the same I²C bus without address conflict-supporting compact multi-node indicator systems without address translation logic.

Does the PCA9550D,112 require external components to generate its blink timing?

No. The PCA9550D,112 contains a fully integrated RC oscillator that drives both BLINK0 and BLINK1 PWM channels. Timing is set solely by writing values to the PSC0/PSC1 (prescaler) and PWM0/PWM1 (duty cycle) registers-no crystals, capacitors, or resistors are needed. This simplifies layout, reduces BOM cost, and improves reliability versus discrete timing solutions. The PCA9550D,112 oscillator operates across the full 2.3–5.5 V supply range.