English
Language : 

TCA9802 Datasheet, PDF (18/36 Pages) Texas Instruments – Level-Translating I2C Bus Buffer/Repeater
◁
TCA9802
SCPS266 – MARCH 2017
www.ti.com
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.
1.65 V
3.3 V
1.65 V
5k
5k
5k
5k
SDA
VCCA VCCB
TCA980x
SDAA SDAB
VCCB VCCA
T/PCA9517
SDAB SDAA
SDA
SCL
BUS
MASTER
400 kHz
SCLA SCLB
EN
SCLB SCLA
SCL
SLAVE
400 kHz
Copyright © 2017, Texas Instruments Incorporated
Figure 17. Incorrect B-Side Static Voltage Offset Buffer Connection
1.65 V
3.3 V
5V
5k
BUS
MASTER
400 kHz
SDA
SCL
5k
VCCA VCCB
TCA980x
SDAA SDAB
SCLA SCLB
5k
VCCA VCCB
T/PCA9517
SDAA SDAB
SCLA SCLB
5k
SDA
SCL
SLAVE
EN
400 kHz
Copyright © 2017, Texas Instruments Incorporated
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.
18
Submit Documentation Feedback
Product Folder Links: TCA9802
Copyright © 2017, Texas Instruments Incorporated
 ▷