基于ISL3300x设计的I2C总线扩展方案

ISL3300x系列(ISL33001, ISL33002, ISL33003)是2路I2C总线双相缓冲器,可以扩展总线的电容超过400pF,工作电压2.3V到5.5V,工作温度-40℃ 到+85℃.,工作频率大于400kHz,具有热插拔功能,主要用在I2C总线扩展器和电容缓冲器,通信,数据通信的服务机架和计算机服务器,台式计算机,板卡热拔和总线隔离.本文介绍ISL3300x系列主要特性, 电路方框图, 典型应用电路框图和ISL3300x评估板主要特性,电路图和元件清单(BOM).

The ISL33001, ISL33002, ISL33003 2-Channel Bus Buffers provide the necessary buffering for extending the bus capacitance beyond the 400pF maximum specified by the I2C specification. In addition, the ISL33001, ISL33002, ISL33003 feature rise time accelerator circuitry to reduce power consumption from passive bus pull-up resistors and improve data-rate performance. All devices also include hot swap circuitry to prevent corruption of the data and clock lines when I2C devices are plugged into a live backplane and level translation for mixed supply voltage applications.

The ISL33001, ISL33002, ISL33003 operates at supply voltages from +2.3V to +5.5V at a temperature range of -40℃ to +85℃.

ISL3300x系列主要特性:

• 2 Channel I2C Compatible Bi-Directional Buffer

• +2.3VDC to +5.5VDC Supply Range

• >400kHz Operation

• Bus Capacitance Buffering

• Rise Time Accelerators

• Hot-Swapping Capability

• ±6kV Class 3 HBM ESD Protection On All Pins

• ±12kV HBM ESD Protection on SDA/SCL Pins

• Enable Pin (ISL33001 and ISL33003)

• Logic Level Translation (ISL33002 and ISL33003)

• READY Logic Pin (ISL33001)

• Accelerator Disable Pin (ISL33002)

• Pb-Free (RoHS Compliant) 8 Ld TDFN (3mmx3mm) and 8 Ld MSOP packages

• Low Quiescent Current . . . . . . . . . . . . . 2.2mA typ

• Low Shutdown Current . . . . . . . . . . . . .  0.5μA typ

ISL3300x 系列应用:

• I2C Bus Extender and Capacitance Buffering

• Server Racks for Telecom, Datacom, and Computer Servers

• Desktop Computers

• Hot-Swap Board Insertion and Bus Isolation

图1.ISL3300x电路方框图

图2.ISL3300x典型应用电路框图

ISL3300x评估板

ISL33001MSOPEVAL1Z, ISL33002MSOPEVAL1Z, ISL33003MSOPEVAL1Z Evaluation Board

The ISL33001MSOPEVAL1Z, ISL33002MSOPEVAL1Z, and ISL33003MSOPEVAL1Z evaluation board is designed to provide a quick and easy method for evaluating the ISL33001, ISL33002, ISL33003 2-Channel Bus Buffer. It is recommended to understand the operation of the IC for a complete utilization of the evaluation board.

The evaluation board is developed to evaluate the performance of the buffer used in a typical application.

The ISL3300x MSOP package IC is soldered onto the evaluation board and is designated as U1. A typical application of the ISL3300x is an I2C bus buffer. The evaluation board contains all the necessary components to interface the buffer to an I2C bus.

Discrete NMOS transistors are used to produce the pull-down functions of a wired-AND bus. Each SDA/SCL pin on the buffer is connected to an external open-drain NMOS transistor. The evaluation board also contains connections for the bus pull-up resistor and load capacitance. The logic input pins on the ISL3300x IC can be held logic High by a pull-up resistor or driven dynamically with an external logic source.

ISL3300x评估板主要特性:

• Evaluation Board for ISL33001IUZ, ISL33002IUZ, and ISL33003IUZ IC in MSOP Package

• +2.3V to +5.5V Supply Operation

• Configured to operate in I2C environment

• Two Channel Supply for Level Shifting Applications (ISL33002 and ISL33003)

• On-Board Discrete NMOS Open-Drain Transistors Connected to SDA/SCL Pins

• 3V Logic for NMOS Transistor Gate

• On-Board Discrete Bus Pull-Up Resistors and Load Capacitance on SDA/SCL Pins

• Convenient Test Points on SDA/SCL pins


图3. ISL3300x评估板外形图

图4. ISL3300x评估板电路图

ISL3300x评估板材料清单(BOM):