PCA9551D,112

Overview

The PCA9551D,112 is an 8-bit I²C-bus and SMBus LED driver manufactured by NXP Semiconductors. It features two fully programmable blink rates generated by an internal oscillator, eliminating the need for external components or continuous host controller intervention. The device provides open-drain outputs capable of sinking up to 25 mA per bit and 100 mA per package. It operates within a supply voltage range of 2.3 V to 5.5 V and supports clock frequencies from 0 Hz to 400 kHz. The component is housed in a SOIC-16 surface-mount package.

Feature Summary

• Integrates an internal oscillator with two independently programmable blink rates for frequency and duty cycle control
• Provides direct LED driving capability via open-drain outputs with specified current limits
• Supports hardware address selection through three pins to allow multiple devices on a single bus
• Includes low-active reset input and power-on reset functionality for reliable initialization

Applications

• LED blinking applications requiring reduced I²C bus communication traffic
• Systems needing to release microcontroller timers for other tasks
• General-purpose parallel input/output expansion where bits are unused for LED control
• ACPI power switch interfaces and sensor monitoring circuits

Procurement Notes

Verify the specific suffix '112' against the manufacturer's latest ordering information to confirm packaging orientation and reel specifications. Confirm that the SOIC-16 variant aligns with your PCB footprint requirements. Check current availability status as product lifecycles may change. Ensure design compatibility with the 2.3 V to 5.5 V operating range and 400 kHz interface speed before finalizing procurement.

Selection Notes

Select this component when application logic requires independent LED flashing without burdening the main processor. It serves as an alternative to standard GPIO expanders like the PCF8574 if timer resources are limited. Consider the 25 mA per-bit sink current for direct LED connection. Verify that the required number of addressable devices fits within the eight-device limit provided by the three hardware address pins.

Part Context

The PCA9551 belongs to NXP's family of I²C-bus LED drivers designed to offload timing-intensive tasks from system controllers. It complements other I/O expanders by offering dedicated hardware blink control. The device shares interface compatibility with SMBus standards, allowing integration into various industrial and consumer electronic systems requiring efficient bus management and peripheral control.

Replacement Considerations

Public confirmed substitute part numbers: PCA9551PW,118; PCA9551HP,118.