TCA9800 Datasheet, PDF (27/36 Pages) Texas Instruments – Level-Translating I2C Bus Buffer/Repeater

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TCA9800
SCPS264 – MARCH 2017
NOTE: The B-side may not be connected to another translator if it uses a static-voltage offset. The R_ILC spec is
violated since the static voltage offset adjusts the output resistance to ground to be outside of the R_ILC spec
requirement, causing the TCA980x to be unable to recognize a low.
1.65 V
3.3 V
1.65 V
5k
SDA
BUS
SCL
MASTER
400 kHz
5k
VCCA VCCB
TCA980x
SDAA SDAB
SCLA SCLB
EN
VCCA VCCB
TCA980x
SDAA SDAB
SCLA SCLB
EN
SDA
SCL
SLAVE
400 kHz
BUS A
BUS B
Figure 34. Series Use Case
BUS C
Copyright © 2017, Texas Instruments Incorporated
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.
10.2.4.1 Design Requirements
The system designer must first select the correct variant of the TCA980x family for the load. In order to do this,
the information in Table 10 and Table 11 must be known. The setup in Figure 34 is used for these example
design requirements.
Parameter
C_L
t_r
V_CCA
V_CCB
f_SCL
Table 10. Design Requirements for Bus B / 1^st TCA980x
Description
Load capacitance (bus capacitance) on B-
side
Rise time
VCCA supply voltage
VCCB supply voltage
I²C clock frequency
Acceptable Range
up to 400 pF
up to 300 ns
0.8 V-3.6 V
1.65 V-3.6 V
Example Value/Target
300 pF
≤ 200 ns
1.65 V
3.3 V
400 kHz
Parameter
C_L
t_r
V_CCA
V_CCB
f_SCL
Table 11. Design Requirements for Bus C / 2^nd TCA980x
Description
Load capacitance (bus capacitance) on B-
side
Rise time
VCCA supply voltage
VCCB supply voltage
I²C clock frequency
Acceptable Range
up to 400 pF
up to 300 ns
0.8 V-3.6 V
1.65 V-3.6 V
Example Value/Target
100 pF
≤ 250 ns
3.3 V
1.65 V
400 kHz
Copyright © 2017, Texas Instruments Incorporated
Product Folder Links: TCA9800
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