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4-Channel I2C/SMBus Bus Switch with Interrupt

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The PI4MSD5V9545A is a quad 1-of-4 bidirectional translating switch, controlled via the I2C/SMBus. The SCL/SDA upstream pair fans out to four SCx/SDx 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. Four interrupt inputs, INT0 to INT3, one for each of the downstream pairs, are provided. One interrupt output, INT, acts as an AND of the four interrupt inputs. An active LOW reset input allows the PI4MSD5V- 9545A/45B/45C to recover from a situation where one of the downstream buses is stuck in a LOW state. Pulling the RESET pin LOW resets the I2C/SMBus 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 VCC pin can be used to limit the maximum high voltage which will be passed by the PI4MSD5V9545A/45B/45C. This allows the use of different bus voltages on each pair, so that 1.2V, 1.8V or 2.5V or 3.3V 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 5V tolerant. The PI4MSD5V9545A , PI4MSD5V9545B and PI4MSD5V9545C are identical except for the fixed portion of the slave address.


  • 1-of-4 bidirectional translating multiplexer
  • I2C-bus interface logic; compatible with SMBus standards
  • Operating power supply voltage range of 1.65V to 5.5V
  • Allows voltage level translation between 1.2V, 1.8V, 2.5V, 3.3V and 5V buses
  • Low standby current
  • Low Ron switches
  • Channel selection via I2C-bus
  • Power-up with all multiplexer channels deselected
  • No glitch on power-up
  • Supports hot insertion
  • 5V tolerant inputs
  • 0 Hz to 400 kHz clock frequency
  • ESD protection exceeds 2000V HBM per JESD22-A114, and 1000V CDM per JESD22-C101
  • Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
  • Packages offered: SOIC (S20), TSSOP (L20)

Product Specifications

Product Parameters

Ambient or Junction Temperature (°C) -40 to 85
Analog or Digital? Digital
Voltage 1.65V/5.5V
Single Ended Channels 4
Signal Type Single Ended
Configuration Switch, 4-channel, 2:1
RailToRail 0
HotInsertion 1

Technical Documents

Design tool model software

Recommended Soldering Techniques


Additional Technical Documents are available upon request:
Application information, Evaluation board, and Other technical documents

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Orderable Part Number Status Package Environmental Compliance Packing Buy from Distributor /
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Qty. Carrier
PI4MSD5V9545ALE Active TSSOP-20 GREEN 74 TUBE Contact Sales Request Sample
PI4MSD5V9545ALEX Active TSSOP-20 TPGP 3000 T&R


Authorized Distributor Quantity Inventory Date Countries/Regions Buy Online
Digi-Key Electronics 2703 12/3/2022 Europe, Asia, North America Buy Now
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Environmental Compliance Legend:
LFF: Pb-Free Finish and RoHS 5/6
TLFP: Totally Pb-Free Product and RoHS 6/6
LFGP: Pb-free Finish and Green Product, RoHS 5/6 and Halogen Free
TPGP: Totally Pb-Free and Green Product, RoHS 6/6 and Halogen Free
GREEN: Halogen-free and RoHS compliant
RoHS: RoHS compliant but NOT halogen-free