pca9306 datasheet

PCA9306
Vref2
Switch Configuration: Vref1 = Vref2 and
Enable is controlled by a GPIO
200 k
VCC1
EN
GPIO: high logic does not
exceed Vref2 + Vth
SCL1
VCC2
SDA1
R
VCC2
SCL2
SDA2
Vref1
VCC2
RR
Where Vcc2 = Vcc1
VCC1 VCC1
Main Board
3.3 V I
2
C bus PCA9306
3.3 V I
2
C bus
EN
GPIO
Note: GPIO logic high must not
exceed 3.3 V +Vth in this example
Remote Board
11
PCA9306
www.ti.com SCPS113M –OCTOBER 2004–REVISED APRIL 2019
Product Folder Links: PCA9306
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Overview (continued)
8.1.4 Supporting Remote Board Insertion to Backplane with PCA9306
Another situation where PCA9306 is advantageous when using its enable feature is when a remote board with
I2C lines needs to be attached to a main board (backplane) with an I2C bus such as in Figure 9. If connecting a
remote board to a backplane is not done properly, the connection could result in data corruption during a
transaction or the insertion could generate an unintended pulse on the SCL line. Which could glitch an I2C
device state machine causing the I2C bus to get stuck.
Figure 9. An example of connecting a remote board to a main board (backplane)
PCA9306 can be used to support this application because it can be disabled while making the connection. Then
it is enabled once the remote board is powered on and the buses on both sides are IDLE.
8.1.5 Switch Configuration
PCA9306 has the capability of being used with its V
REF1
voltage equal to V
REF2
. This essentially turns the device
from a translator to a device which can be used as a switch, and in some situations this can be useful. The
switch configuration is shown in Figure 10 and translation mode is shown in Figure 11.
Figure 10. Switch Configuration