This dual bidirectional I2C and SMBus voltage-level
translator, with an enable (EN) input, is operational from 1.2-V to 3.3-V
VREF1 and 1.8-V to 5.5-V VREF2.
The PCA9306-Q1 allows bidirectional voltage translations between 1.2 V and 5 V, without
the use of a direction pin. The low ON-state resistance (ron) of the switch
allows connections to be made with minimal propagation delay. When EN is high, the translator
switch is ON, and the SCL1 and SDA1 I/O are connected to the SCL2 and SDA2 I/O, respectively,
allowing bidirectional data flow between ports. When EN is low, the translator switch is off, and a
high-impedance state exists between ports.
In I2C applications, the bus capacitance limit of 400 pF
restricts the number of devices and bus length. Using the PCA9306-Q1 enables the system designer to
isolate two halves of a bus; thus, more I2C devices or longer trace
length can be accommodated.
The PCA9306-Q1 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.
All channels have the same electrical characteristics, and there is minimal deviation
from one output to another in voltage or propagation delay. This is a benefit over discrete
transistor voltage translation solutions, because the fabrication of the switch is symmetrical. The
translator provides excellent ESD protection to lower-voltage devices and at the same time protects
less ESD-resistant devices.