NXP Semiconductors PCA9551BSHP

Overview

PCA9551BSHP from NXP Semiconductors is an 8-bit I²C-bus LED blinker with dual programmable blink rates (0.148–38 Hz), internal oscillator, and open-drain outputs capable of sinking 25 mA per channel and 100 mA total. It offloads LED timing from the host MCU in embedded control panels, status indicators, and industrial HMIs where bus traffic reduction and timer conservation are critical.

For engineers reviewing the PCA9551BSHP datasheet, PCA9551BSHP pinout, PCA9551BSHP application, or PCA9551BSHP equivalent, key selection criteria include its dual independent PWM blink rates, GPIO reuse capability for unused LED pins, HVQFN16 thermal-enhanced package, I²C Fast-mode support (400 kHz), and hardware reset with Power-On Reset (POR) functionality.

Technical Context

The PCA9551BSHP integrates a dedicated internal oscillator-requiring no external components-to generate two independent blink frequencies via prescaler registers PSC0/PSC1 and PWM registers PWM0/PWM1. Its 8-bit output architecture supports per-pin configuration (ON/OFF/BLINK0/BLINK1) through LED selector registers LS0/LS1.

It operates across 2.3 V to 5.5 V, features noise-filtered SCL/SDA inputs, edge-rate-controlled outputs, and supports hot insertion. The device implements Auto-Increment register addressing and includes input filtering, ESD protection (>2000 V HBM), and latch-up immunity per JEDEC JESD78.

Key Specifications

Pinout & Package

HVQFN16 package: plastic thermal-enhanced very thin quad flat package, 4 × 4 × 0.85 mm body, 16-terminal no-lead construction with exposed thermal pad requiring PCB soldering for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9551BSHP, PCA9634PW adds per-channel PWM dimming and higher current capacity but lacks identical blink register compatibility, while PCA9554APW provides basic I/O expansion without autonomous blink functionality-making PCA9551BSHP the optimal choice for applications prioritizing low-overhead, dual-rate LED timing.

Availability

PCA9551BSHP is available at Aetrix Electronics and suitable for industrial control panels, consumer appliance UIs, and network equipment status indicators requiring stable component supply, long-term lifecycle support, and thermal-enhanced packaging.

Supply support for PCA9551BSHP 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 power-efficient mixed-signal design.

The PCA9551BSHP belongs to NXP's I²C-bus LED driver family, engineered to reduce MCU resource load in embedded systems by integrating autonomous blink logic, robust bus interface, and flexible GPIO reuse-all within compact, thermally optimized packages.

FAQ

What is the primary function of the PCA9551BSHP?

The PCA9551BSHP is an 8-bit I²C-bus LED blinker that autonomously controls up to eight LEDs using two independently programmable blink rates (BLINK0 and BLINK1). It eliminates the need for continuous MCU intervention by executing blink timing internally via its integrated oscillator and prescaler/PWM registers-reducing I²C bus traffic and freeing MCU timers. The PCA9551BSHP also supports GPIO reuse for unused LED pins.

Does the PCA9551BSHP require external components to generate blink signals?

No-the PCA9551BSHP contains a fully integrated internal oscillator that requires no external crystal, resonator, or capacitors to generate its dual blink rates. This simplifies BOM, reduces PCB footprint, and improves system reliability. All timing parameters (frequency and duty cycle) are configured via I²C-accessible registers PSC0/PSC1 and PWM0/PWM1. The PCA9551BSHP operates immediately after power-up or reset with default settings.

How does the PCA9551BSHP handle power-up and reset conditions?

The PCA9551BSHP incorporates both Power-On Reset (POR) and an active-low hardware RESET pin. During power-up, POR holds the device in reset until VDD reaches VPOR (1.7–2.2 V), then initializes all registers to default states-setting all outputs HIGH (LEDs OFF). Asserting RESET LOW for ≥8 ns forces the same initialization. Both mechanisms ensure deterministic, glitch-free startup. The PCA9551BSHP guarantees no unintended LED activation at power-on.

Can unused LED pins on the PCA9551BSHP be used as general-purpose I/Os?

Yes-any LEDn pin not configured for blink or static LED control can be repurposed as a bidirectional GPIO. To use as input, configure the pin to high-impedance (01) via the LS0/LS1 registers and read its state from the INPUT register. To use as output, connect an external pull-up resistor and program the pin LOW (00) or HIGH-Z (01); pulse-width control remains available via BLINK0/BLINK1. This flexibility extends the PCA9551BSHP's utility beyond LED driving.

What are the thermal and packaging advantages of the PCA9551BSHP's HVQFN16 variant?

The PCA9551BSHP in HVQFN16 (SOT629-1) features a 4 × 4 × 0.85 mm thermally enhanced no-lead package with an exposed center pad. When soldered to a PCB thermal pad with vias, it achieves significantly better thermal dissipation than SO16 or TSSOP16 variants-critical for sustained 100 mA total sink current operation. This makes the PCA9551BSHP ideal for space-constrained, high-density, or thermally demanding applications like network equipment front panels.