PCA9551PW,118

Overview

The PCA9551PW,118 is an 8-bit I²C-bus LED driver featuring programmable blink rates. It operates within a voltage range of 2.3 V to 5.5 V and supports clock frequencies from 0 Hz to 400 kHz. The device provides eight open-drain outputs capable of sourcing up to 25 mA per bit and 100 mA per package. It includes two fully programmable blink rates with internal oscillators, eliminating the need for external components. Unused bits function as general-purpose I/O.

Feature Summary

• Integrates an internal oscillator to provide two independently programmable blink rates without external components.
• Supports I²C bus and SMBus interfaces with noise filters on SCL and SDA inputs.
• Features low-active hardware reset and power-on reset to initialize registers to default states.
• Allows unused output bits to operate as general-purpose parallel input/output expansion.

Applications

• I²C bus applications requiring limited bus communication traffic
• SMBus applications needing LED status indication
• Systems requiring release of MCU timers for LED blinking control

Procurement Notes

Verify the suffix '118' corresponds to the TSSOP16 tape and reel packaging configuration. Confirm the manufacturer is NXP Semiconductors. Ensure the part number matches the specific ordering code for this variant. Check datasheet revisions for any updates regarding electrical characteristics or pin assignments before finalizing procurement.

Selection Notes

Select this component when independent software control of LED blinking is required via I²C. It is suitable for designs needing to offload timer resources from the main microcontroller. Consider the 25 mA per-bit sink current capability for direct LED driving. Verify that the 2.3 V to 5.5 V supply range aligns with the system power architecture.

Part Context

This part belongs to the PCA955x series of I²C-bus LED drivers. It shares functional similarities with the PCA9550 but offers eight channels instead of two. It differs from GPIO expanders like the PCA9554 by providing dedicated hardware blink rate programming rather than simple on/off switching.

Replacement Considerations

PCA9550 (2-channel variant)

FAQ

How are the blink rates programmed?

The blink rates are programmed via initial setup commands to the BLINK RATE 1 and BLINK RATE 2 registers, defining frequency and duty cycle.

Can unused pins be used for other purposes?

Yes, any bits not configured for LED driving can be utilized as general-purpose parallel input/output (GPIO) expansion.