ZHCSG40B March 2017 – February 2020 TCA9801
PRODUCTION DATA.
- 1 特性
- 2 應用
- 3 說明
- 4 修訂歷史記錄
- 5 Device Comparison Table
- 6 Pin Configuration and Functions
- 7 Specifications
- 8 Parameter Measurement Information
-
9 Detailed Description
- 9.1 Overview
- 9.2 Functional Block Diagram
- 9.3
Feature Description
- 9.3.1 Integrated Current Source
- 9.3.2 Ultra-Low Power Consumption
- 9.3.3 No Static-Voltage Offset
- 9.3.4 Active-High Repeater Enable Input
- 9.3.5 Powered Off High Impedance I2C Bus Pins on A-Side
- 9.3.6 Powered-Off Back-Power Protection for I2C Bus Pins
- 9.3.7 Clock Stretching and Multiple Master Arbitration Support
- 9.4 Device Functional Modes
- 10Application and Implementation
- 11Power Supply Recommendations
- 12Layout
- 13器件和文檔支持
- 14機械、封裝和可訂購信息
10.1.2.2 Buffered Translators/Level-shifters
The TCA980x family supports connections with buffered translators, but care must be taken to ensure that no operating conditions be violated. In a general sense, the following must be avoided on the B-side ports of the TCA980x:
- Sources of current other than the individual TCA980x (B-side of the other TCA980x, external pull-up resistors, current sources, rise time accelerators, etc)
- Static-voltage offset buffer outputs (B-side of the TCA9517, etc)
- Outputs with RILC (equivalent pull-down resistance) > 150 Ω
It is important to note that these special operating requirements apply only to the B-side ports of the TCA980x. For example, the TCA9517 B-side can be safely connected to the A-side of the TCA980x, but not to the B-side of the TCA980x. However, it is OK to connect the A-side of the TCA9517 to the B-side (or A-side) of the TCA980x, because the A-side does not have a static voltage offset based output.
Figure 17 shows an example of the incorrect connection on the B-side to a buffer with a static voltage offset output. The reason this is unacceptable is because the equivalent output resistance of the output buffer is greater than the maximum RILC allowed. See the RILC section for more information.
Figure 17. Incorrect B-Side Static Voltage Offset Buffer Connection 
Figure 18. Correct Connection With Other Buffers NOTE
Decoupling capacitors are not shown to keep the illustration simple. Decoupling capacitors (1 µF and 0.1 µF) must be placed close to each power supply pin.
As shown in Figure 18, this connection is acceptable for use on the B-side ports of the TCA980x, because the equivalent RILC of the A-side of this example buffer is less than 150 Ω.