1 General description

The PCA9847 is an ultra-low voltage, octal bidirectional translating multiplexer controlled via the I2C-bus. The SCL/SDA upstream pair fans out to eight downstream pairs, or channels. Any single SCx/SDx channel can be selected, determined by the programmable control register. This feature allows multiple devices with the same I2C-bus address to reside on the same bus. The multiplexer device can also separate a heavily loaded I2C-bus into separate bus segments, eliminating the need for a bus buffer. An active LOW reset input allows the PCA9847 to recover from a situation where one of the downstream I2Cbuses is stuck in a LOW state. Pulling the RESET pin LOW resets the I2C-bus state machine and deselects all the channels, as does the internal Power-On Reset (POR) function. The pass gates of the multiplexers are constructed such that the VDD1 or VDD2 pin is used to limit the maximum high voltage which is passed by the PCA9847. This allows the use of different bus voltages on each channel, so that 0.8 V, 1.8 V, 2.5 V or 3.3 V parts can communicate without any additional protection. External pull-up resistors pull the bus up to the desired voltage level for each channel. All I/O pins are 3.6 V tolerant.

2 Features and benefits

• Ultra-low voltage operation, down to 0.8 V to interface with next-generation CPUs

• 1-of-8 bidirectional translating multiplexer

• Fm+ I2C-bus interface logic; compatible with SMBus standards

• Active LOW reset input

• 2 address pins allowing up to 16 devices on the I2C-bus

• Channel selection via I2C-bus

• Power-up with all multiplexer channels deselected

• Low Ron switches

• Allows voltage level translation between 0.8 V, 1.8 V, 2.5 V and 3.3 V buses

• Reset via I2C-bus software command

• I2C Device ID function

• No glitch on power-up

• Supports hot insertion since all channels are deselected at power-on

• Low standby current

• 3.6 V tolerant inputs

• 0 Hz to 1 MHz clock frequency

• ESD protection exceeds 6000 V HBM per JESD22-A114 and 1000 V CDM per JESD22-C101

• Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA

• Two packages offered: TSSOP24 and HVQFN24