PCA9849是NXP公司的一款I2C增强快速模式产品，PCA9849是4-channel ultra-low voltage, Fm+ I2C-bus multiplexer with reset，本站介绍了PCA9849的封装应用图解、特点和优点、功能等，并给出了与PCA9849相关的NXP元器件型号供参考。
PCA9849 - 4-channel ultra-low voltage, Fm+ I2C-bus multiplexer with reset - I2C增强快速模式 - I2C - 恩智浦, LLC
The PCA9849 is an ultra-low voltage, quad bidirectional translating multiplexercontrolled via the I2C-bus. The SCL/SDA upstream pair fans out to fourdownstream pairs, or channels. A single SCx/SDx channel can be selected, determined bythe programmable control register. This feature allows multiple devices with the sameI2C-bus address to reside on the same bus. The multiplexer device canalso separate a heavily loaded I2C-bus into separate bus segments,eliminating the need for a bus buffer.
An active LOW reset input allows the PCA9849 to recover from a situation where one of thedownstream I2C-buses is stuck in a LOW state. Pulling the RESET pin LOW resets the I2C-bus state machineand deselects all the channels, as does the internal Power-On Reset (POR) function.
The pass gates of the switches are constructed such that the VDD1 pin is usedto limit the maximum high voltage which is passed by the PCA9849. This allows the use ofdifferent bus voltages on each channel, so that 0.8 V, 1.8 V, 2.5 V or 3.3 V parts cancommunicate without any additional protection. External pull-up resistors pull the busup to the desired voltage level for each channel. All I/O pins are 3.6 V tolerant.
