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Part Number Description Max frequency (kHz) Vcc Range(V) Chnnel width Interrupt Reset Simulta neously active channels 5V-to lerant I/O Push-pull Open-drain Cross Reference Pin/Package
AT9548A 8-channel I2C bus switch with reset 400 2.3~5.5 8 channel 1~8 PCA9548A SOP24 TSSOP24 QFN24


     TheAT9548A is an octal bidirectional translating switch controlled via the I2C-bus. The SCL/SDA upstream pair fans out to eight downstream pairs, or channels. Any individual SCx/SDx channel or combination of channels can be selected, determined by the contents of the programmable control register.

An active LOW reset input allows the AT9548A to recover from a situation where one of the downstream I2C-buses is stuck in a LOW state. Pulling the RESET pin LOW resets the I2C-bus state machine and causes all the channels to be deselected as does the internal Power-on reset function.

The pass gates of the switches are constructed such that the VDD pin can be used to limit the maximum high voltage which will be passed by the AT9548A. This allows the use of different bus voltages on each pair, so that 1.8 V or 2.5 V or 3.3 V parts can communicate with 5V parts 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 6V tolerant.


1-of-8 bidirectional translating switches

2C-bus interface logic; compatible with SMBus standards

Active LOW reset input

Three address pins allowing up to eight devices on the I2C-bus

Channel selection via I2C-bus, in any combination

Power-up with all switch channels deselected

Low Ron switches

Allows voltage level translation between 1.8 V, 2.5 V, 3.3 V and 5 V buses

No glitch on power-up

Supports hot insertion

Low standby current

Operating power supply voltage range of 2.3 V to 5.5 V

6 V tolerant inputs

0 Hz to 400 kHz clock frequency

ESD protection exceeds 2000 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

Three packages offered: SO24, TSSOP24, and HVQFN24

Typical Application


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