PCA9547D,112

Specialized Overview

The PCA9547D,112 is an octal bidirectional translating multiplexer controlled by the I2C-bus. It fans out one upstream SCL/SDA pair to eight downstream pairs (SCx/SDx). The device operates within a supply voltage range of 2.3 V to 5.5 V and supports clock frequencies from 0 Hz to 400 kHz. It features low on-state resistance, with maximum values of 65 Ohms at 2.3 V–2.7 V and 54 Ohms at 4.5 V–5.5 V. The component includes an active LOW reset input and three hardware address pins (A0-A2), allowing up to eight devices on a single bus. It is housed in a SO24 package.

Specialized Feature Summary

• Provides voltage level translation between 1.8 V, 2.5 V, 3.3 V, and 5 V buses using the VDD pin to limit passed high voltage.
• Includes an active LOW reset input to recover from stuck bus conditions by deselecting all channels except Channel 0.
• Supports hot insertion and ensures no glitch occurs during power-up.
• Features low standby current consumption and robust ESD protection exceeding 2000 V HBM.

Specialized Applications

• Expanding I2C/SMBus slave device capacity beyond the standard addressing limits.
• Connecting multiple I2C peripherals operating at different voltage levels to a single master controller.
• Isolating downstream I2C buses to prevent faults on one channel from affecting others.

Specialized Procurement Notes

Verify the specific ordering suffix '112' corresponds to the SO24 tube packaging configuration as defined in the manufacturer's ordering information table. Confirm that the ambient temperature rating aligns with the -40 °C to +85 °C specification required for the target application environment before finalizing procurement orders.

Specialized Selection Notes

Select this component when an I2C master requires access to more than eight slaves or needs to interface with devices operating at varying logic voltages. Ensure the design accommodates the requirement for external pull-up resistors on both the upstream and downstream lines, as internal pull-ups are not provided for the address pins.

Specialized Part Context

This part belongs to the PCA954X family of I2C/SMBus multiplexers and switches. While other variants like the PCA9545 offer fewer channels, the PCA9547 specifically provides eight channels. The 'D' designation indicates the SO24 plastic small outline package, distinguishing it from TSSOP or HVQFN options available within the same functional family.

Specialized Replacement Considerations

PCA9547PW,112

Specialized FAQ

How does the PCA9547 handle voltage translation?

The pass gate transistors allow the VDD pin voltage to limit the maximum high voltage passed to the downstream channels. This enables communication between 5 V parts and lower voltage parts (e.g., 1.8 V, 2.5 V, or 3.3 V) without additional protection components.

What happens to the channel selection upon power-up?

Upon power-up, the device initializes with all channels deselected except Channel 0, which is connected. This allows immediate communication between the master and downstream devices on Channel 0.

Can multiple channels be selected simultaneously?

No, only one SCx/SDx channel can be selected at a time. Selection is determined by the contents of the programmable control register accessed via the I2C-bus.