PCA9518D,112

Specialized Overview

The PCA9518D,112 is a BiCMOS expandable five-channel I2C-bus hub manufactured by NXP Semiconductors. It operates within a supply voltage range of 3.0 V to 3.6 V and supports clock frequencies up to 400 kHz. The device provides five bidirectional open-drain buffers for SDA and SCL lines, enabling the expansion of I2C systems beyond the standard 400 pF capacitance limit. It features active HIGH enable inputs (EN1-EN4) for individual channel control and four expansion pins (EXPSCL1, EXPSCL2, EXPSDA1, EXPSDA2) for clustering multiple units. The component is housed in an SO20 plastic small outline package with a body width of 7.5 mm.

Specialized Feature Summary

• Expandable architecture allowing unlimited bus segmentation via dedicated expansion pins
• Lock-up free operation ensuring stable arbitration and clock stretching across repeaters
• 5 V tolerant I/O pins compatible with mixed voltage environments
• Powered-off high-impedance state preventing leakage when VDD is below operating thresholds

Specialized Applications

• I2C-bus system expansion where total capacitance exceeds 400 pF limits
• Multi-master configurations requiring segment isolation
• SMBus applications needing buffered signal integrity
• Systems integrating devices with different voltage levels (e.g., 3.3 V and 5 V)

Specialized Procurement Notes

Verify the ordering suffix '112' against current NXP documentation to confirm specific tape-and-reel packaging or moisture sensitivity level requirements. Ensure the selected variant matches the required SO20 package dimensions and lead pitch specifications for PCB footprint compatibility.

Specialized Selection Notes

Select this component when designing systems that require more than five isolated I2C segments or need to overcome strict capacitance constraints. Consider the 3.0 V to 3.6 V supply requirement and ensure the design accommodates the necessary pull-up resistors on all enabled ports and expansion lines.

Specialized Part Context

This part belongs to the PCA9518 series of expandable I2C hubs. It serves as a bridge between master controllers and multiple slave subsystems, effectively multiplying the number of available I2C addresses while maintaining signal integrity through buffering.

Specialized Replacement Considerations

PCA9518D: Direct equivalent from NXP with identical electrical characteristics and pinout.

Specialized FAQ

Can unused channels be left floating?

No, unused channels must have pull-up resistors unless their respective enable pins (ENn) are permanently held LOW.

Is it possible to chain PCA9518 clusters in series?

No, PCA9518 clusters cannot be put in series with other PCA9515/16 or separate PCA9518 clusters; they must be grouped using the EXPxxxn pins.

What happens if VDD drops below 2.0 V?

The I2C-bus I/O pins enter a high-impedance state to prevent unintended bus activity during power-down conditions.