Datasheet

1
2
3
4
5
6
7
8
SW
SW
V = 1.8 V
REF1
V = 3.3 V
DPU
I C Bus
Master
2
I C Bus
Device
2
V
REF1
V
REF2
EN
V
CC
V
CC
PCA9306
GND
GND
GND
SDA
SDA1
SDA2
200 kΩ
SCL1
SCL
SCL
SDA
SCL2
R
PU
R
PU
R
PU
R
PU
PCA9306
www.ti.com SCPS113J –OCTOBER 2004–REVISED OCTOBER 2010
APPLICATION INFORMATION
General Applications of I
2
C
In I
2
C applications, the bus capacitance limit of 400 pF restricts the number of devices and bus length. Using the
PCA9306 enables the system designer to isolate two halves of a bus; thus, more I
2
C devices or longer trace
length can be accommodated.
The PCA9306 also can be used to run two buses, one at 400-kHz operating frequency and the other at 100-kHz
operating frequency. If the two buses are operating at different frequencies, the 100-kHz bus must be isolated
when the 400-kHz operation of the other bus is required. If the master is running at 400 kHz, the maximum
system operating frequency may be less than 400 kHz because of the delays added by the repeater.
As with the standard I
2
C system, pullup resistors are required to provide the logic high levels on the translator's
bus. The PCA9306 has a standard open-collector configuration of the I
2
C bus. The size of these pullup resistors
depends on the system, but each side of the repeater must have a pullup resistor. The device is designed to
work with standard-mode and fast-mode I
2
C devices, in addition to SMBus devices. Standard-mode I
2
C devices
only specify 3 mA in a generic I
2
C system where standard-mode devices and multiple masters are possible.
Under certain conditions, high termination currents can be used.
Figure 2. Typical Application Circuit (Switch Always Enabled)
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