SCPS267B March 2017 – February 2020 TCA9803
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:
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.
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.