PCA9518AD,112

Specialized Overview

The PCA9518AD,112 is an expandable five-channel I2C-bus hub manufactured by NXP Semiconductors. It buffers both data (SDA) and clock (SCL) lines to extend the bus beyond the standard 400 pF capacitance limit. The device supports Standard-mode and Fast-mode I2C devices with a supply voltage range of 2.3 V to 3.6 V. It features open-drain inputs/outputs, active HIGH enable pins, and lock-up free operation. The component is housed in a 20-lead SO plastic small outline package (SO20).

Specialized Feature Summary

• Expandable 5-channel bidirectional buffer for I2C-bus and SMBus systems.
• Lock-up free operation with powered-off high-impedance I2C-bus pins.
• Supports arbitration and clock stretching across the repeater.

Specialized Applications

• I2C-bus system expansion using multiple hubs.
• Connecting multiple masters on each segment.
• Buffering SDA and SCL lines to increase bus length.

Specialized Procurement Notes

Verify the specific ordering suffix '112' against the manufacturer's current documentation to confirm packaging details. Ensure compatibility with the required operating temperature range of -40 °C to +85 °C. Confirm that the SO20 package variant matches the design constraints.

Specialized Selection Notes

Select this component when expanding I2C networks beyond standard capacitance limits. It allows unlimited bus segments with only one repeater delay. Use when 5V tolerance is required for I2C and enable pins while operating at lower supply voltages.

Specialized Part Context

This part belongs to the PCA9518A series, which is a wider voltage range version of the PCA9518. It improves partial power-down performance by keeping I2C-bus I/O pins in a high-impedance state when VDD is below 2.0 V.

Specialized Replacement Considerations

PCA9518APW is a TSSOP20 package alternative within the same family. Verify pinout and electrical characteristics before substitution.

Specialized FAQ

Can PCA9518 clusters be put in series with PCA9515 or PCA9516?

No, a PCA9518 cluster cannot be put in series with a PCA9515/16 or another PCA9518 cluster not connected via EXPxxxn pins.

What is the function of the expansion pins?

The four open-drain I/O pins (EXPSDA1, EXPSDA2, EXPSCL1, EXPSCL2) are used to communicate the internal state of the serial data within each hub to other hubs, allowing expansion in increments of five.

How does the device handle low voltage conditions?

It keeps I2C-bus I/O pins in a high-impedance state when VDD is below 2.0 V, improving partial power-down performance.