TCA9617B Datasheet, PDF (10/24 Pages) Texas Instruments – Level-Translating FM+ I2C Bus Repeater

TCA9617B
SCPS259A – DECEMBER 2014 – REVISED DECEMBER 2014
9.2 Functional Block Diagram
V_CCA
1
V_CCB
8
3
SDAA
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6
SDAB
2
SCLA
7
SCLB
5
EN
V_CCB
Pullup
Resistor
4
GND
9.3 Feature Description
9.3.1 Bidirectional Level Translation
The TCA9617B can provide bidirectional voltage level translation (up-translation and down-translation) between
low voltages (down to 0.8 V) and higher voltages (2.2 V to 5.5 V) in mixed-mode applications.
9.3.2 Low to High Transition Characteristics
Figure 8 depicts the offset voltage on the B side of the device. As shown in Figure 8 the slave releases and the
B-side rises, and it will rise to 0.5 V and stay there until the A-side rises above 0.3 V_CCA. This effect can cause
the low level signal to have a "pedestal." Once the voltage on the A-side crosses 0.3 V_CCA, the B-side will
continue to rise to V_CCB.
Due to nature of the B-side pedestal and the static offset voltage, there will be a slight overshoot as the B-side
rises from being externally driven low to the 0.5 V offset. The TCA9617B is designed to control this behavior
provided the system is designed with rise times greater than 20 ns. Therefore, care should be taken to limit the
pull-up strength when devices with rise time accelerators are present on the B side. Excessive overshoot on the
B-side pedestal may cause devices with rise time accelerators to trip prematurely if the overshoot is more than
accelerator thresholds. Since the A-side does not have a static offset low voltage, no pedestal is seen on the A-
side as shown in Figure 7.
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