BUS

MASTER

400 kHz

SDA

SCL

1.65 V

5 k

5 k

EN

SDAA

SCLA

SDAB

SCLB

VCCA

VCCB

TCA980x

SDA

SCL

SLAVE

400 kHz

3.3 V

VCCA

VCCB

T/PCA9517

5 V

5 k

5 k

SDAA

SCLA

SDAB

SCLB

Copyright © 2017, Texas Instruments Incorporated

BUS

MASTER

400 kHz

SDA

SCL

1.65 V

5 k

5 k

EN

SDAA

SCLA

SDAB

SCLB

VCCA

VCCB

TCA980x

SDA

SCL

SLAVE

400 kHz

3.3 V

VCCB

VCCA

T/PCA9517

1.65 V

5 k

5 k

SDAB

SCLB

SDAA

SCLA

Copyright © 2017, Texas Instruments Incorporated

18

TCA9803

SCPS267B – MARCH 2017 – REVISED FEBRUARY 2020

www.ti.com

Product Folder Links: TCA9803

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Copyright © 2017–2020, Texas Instruments Incorporated

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.

10.2 Typical Application

10.2.1 Single Device

The typical application for the TCA980x family is to be used as a buffering translator, where the VCCA and VCCB

are at different values in order to level-shift the I2C bus voltages.