PCA9540B是一款二选一双向变换多路复用器，通过I²C总线进行控制。SCL/SDA上游对会扇出两个SCx/SDx下游对或通道。一次只选择一条SCx/SDx通道，由可编程控制寄存器的内容决定。
上电复位功能会将寄存器设为其默认状态并初始化I²C总线状态机而不选择任何通道。
多路复用器的传递门如此构造，使得VDD引脚可用于限制PCA9540B所传递的最高电压。这允许在各SCx/SDx对上使用不同的总线电压，在没有任何额外保护的情况下使1.8 V、2.5 V或3.3 V部件能够与5 V部件通信。外部上拉电阻可将总线上拉至该通道想要的电压电平。所有I/O引脚均为5 V耐受。
| 型号 | 可订购的器件编号 | 订购码 (12NC) | 产品状态 | 封装 |
| PCA9540BDP | 9352 760 36118 | PCA9540BDP,118 | 量产 | TSSOP8 (SOT505-1) |
| PCA9540BDP/DG | 9352 933 84118 | PCA9540BDP/DG,118 | 量产 | TSSOP8 (SOT505-1) |
| 型号 | 订购码 (12NC) | 可订购的器件编号 | 化学成分 |
| PCA9540BDP | 9352 760 36118 | PCA9540BDP,118 | PCA9540BDP |
| PCA9540BDP/DG | 9352 933 84118 | PCA9540BDP/DG,118 | PCA9540BDP/DG |
| 档案名称 | 标题 | 类型 | 格式 |
| PCA9540BDP | 2-channel I2C-bus multiplexer | Data sheet | |
| AN10441 | Level shifting techniques in I2C-bus design | Application note | |
| AN255 | I2C / SMBus Repeaters, Hubs and Expanders | Application note | |
| AN10710 | Features and applications of the PCA9540B I2C-bus extender | Application note | |
| 75016527 | Extend standard I2C-bus devices without worrying about offset voltages; NXP I2C-bus extender PCA9540B in a proven application | Brochure | |
| 75016532 | Extend the I2C-bus with advanced repeaters and hubs; NXP 2-channel I2C-bus repeaters PCA9540Bx and 5-channel I2C-bus hubs PCA9516x | Leaflet | |
| 75016080 | Extend the reach of any I2C-bus system without special offset voltage levels; NXP I2C-bus extender PCA9540B | Leaflet | |
| 75017424 | NXP I2C-bus solutions 2013: Smart, simple solutions for the 12 most common design concerns | Leaflet | |
| UM10204 | I2C-bus specification and user manual | User manual | |
| UM10206 | I2C Demonstration Board 2005-1 Quick Start Guide | User manual | |
| UM10323 | PCA9600 demonstration board OM6293 | User manual |
