Datasheet

PCA9541A All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 5 — 24 April 2014 25 of 45
NXP Semiconductors
PCA9541A
2-to-1 I
2
C-bus master selector with interrupt logic and reset
9.2 High reliability systems
In a typical multipoint application, shown in Figure 18, the two masters (for example,
primary and back-up) are located on separate I
2
C-buses that connect to multiple
downstream I
2
C-bus slave cards/devices via a PCA9541A/01 for non-hot swap
applications to provide high reliability of the I
2
C-bus.
I
2
C-bus commands are sent via the primary or back-up master and either master can take
command of the I
2
C-bus. Either master at any time can gain control of the slave devices if
the other master is disabled or removed from the system. The failed master is isolated
from the system and does not affect communication between the on-line master and the
slave devices located on the cards.
For even higher reliability in multipoint backplane applications, two dedicated masters can
be used for every card as shown in Figure 19
.
Fig 18. High reliability backplane application
Fig 19. Very high reliability backplane application
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MASTER 1
SCL1
SDA1
MASTER 0
PCA9541A PCA9541A PCA9541A PCA9541A PCA9541A PCA9541A PCA9541A PCA9541A
SCL0
SDA0
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SCL1
SDA1
MASTER 0
PCA9541A
SCL0
SDA0
MASTER 0MASTER 0MASTER 0
SCL0
SDA0
SCL0
SDA0
SCL0
SDA0
MASTER 1MASTER 1MASTER 1MASTER 1
SCL1
SDA1
SCL1
SDA1
SCL1
SDA1
PCA9541A
PCA9541A
PCA9541A