TCA9617B Datasheet, PDF (12/24 Pages) Texas Instruments – Level-Translating FM+ I2C Bus Repeater

TCA9617B
SCPS259A – DECEMBER 2014 – REVISED DECEMBER 2014
www.ti.com
10 Application and Implementation
10.1 Application Information
A typical application is shown in Figure 9. In this example, the system master is running on a 0.9-V I²C bus, and
the slave is connected to a 2.5-V bus. Both buses are running at 400 kHz. Decoupling capacitors are required
but are not shown in Figure 14 for simplicity.
The TCA9617B is 5-V tolerant so no additional circuits are required to translate between 0.8-V to 5.5-V bus
voltages and 2.7-V to 5.5-V bus voltages.
When the A side of the TCA9617B is pulled low by a driver on the I²C bus, a comparator detects the falling edge
when it goes below 0.7 V_CCA and cause the internal driver on the B side to turn on. The B-side will first pull down
to 0 V and then settle to 0.5 V. When the B side of the TCA9617B falls below 0.45 V, the TCA9617B will detect
the falling edge, turn on the internal driver on the A side and pull the A-side pin down to ground.
On the B-side bus of the TCA9617B, the clock and data lines will have a positive offset from ground equal to the
V_OL of the TCA9617B. After the eighth clock pulse, the data line is pulled to the V_OL of the slave device, which is
close to ground in this example. At the end of the acknowledge, the level rises only to the low level set by the
driver of the TCA9617B for a short delay (approximately 0.5 V), while the A-side bus rises above 0.3 V_CCA and
then continues high.
Although the TCA9617 has a single application, the device can exist in multiple configurations. Figure 9 shows
the standard configuration for the TCA9617. Multiple TCA9617s can be connected either in star configuration
(Figure 12) or in series configuration (Figure 13). The design requirements , detailed design procedure, and
application curves in Standard Application are valid for all three configurations.
10.2 Typical Application
10.2.1 Standard Application
0.9 V
2.5 V
240
240
820
820
VCCA VCCB
SDAA
SCLA
SDAB
SCLB
Master
1 MHz
TCA9617B
EN
BUS A
BUS B
Figure 9. Bidirectional Voltage Level Translator
10.2.1.1 Design Requirements
For the level-translating application, the following should be true:
• V_CCA = 0.8 V to 5.5 V
• V_CCB = 2.2 V to 5.5 V
• V_CCA < V_CCB
• I_OL > I_O
Slave
1 MHz
12
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