PCA9548 Philips Semiconductors, PCA9548 Datasheet - Page 6

• Manufacturer Part Number: PCA9548
• Description: 8-channel I2C switch with reset
• Manufacturer: Philips Semiconductors

Philips Semiconductors
VOLTAGE TRANSLATION
The pass gate transistors of the PCA9548 are constructed such that
the V
be passed from one I
2004 Sep 30
V
8-channel I
pass
DD
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
voltage can be used to limit the maximum voltage that will
2.0
2.5
Figure 5. V
2
TYPICAL
2
C-bus to another.
C switch with reset
3.0
pass
V
pass
MAXIMUM
3.5
vs. V
voltage vs. V
DD
V
4.0
DD
4.5
DD
MINIMUM
5.0
SW00820
5.5
6
Figure 5 shows the voltage characteristics of the pass gate
transistors (note that the PCA9548 is only tested at the points
specified in the DC Characteristics section of this datasheet). In
order for the PCA9548 to act as a voltage translator, the V
voltage should be equal to, or lower than the lowest bus voltage. For
example, if the main bus was running at 5 V, and the downstream
buses were 3.3 V and 2.7 V, then V
2.7 V to effectively clamp the downstream bus voltages. Looking at
Figure 5, we see that V
PCA9548 supply voltage is 3.5 V or lower so the PCA9548 supply
voltage could be set to 3.3 V. Pull-up resistors can then be used to
bring the bus voltages to their appropriate levels (see Figure 12).
More Information can be found in Application Note AN262 PCA954X
family of I
2
C/SMBus multiplexers and switches.
pass
(max.) will be at 2.7 V when the
pass
should be equal to or below
PCA9548
Product data sheet
pass