PCA9641BSHP datasheet(36/55 Pages) NXP

36 / 55 page

PCA9641

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Product data sheet

Rev. 2.1 — 27 October 2015

36 of 55

NXP Semiconductors

PCA9641

2-channel I2C-bus master arbiter

16.4 Gatekeeper multiplexer

The PCA9641 can act as a gatekeeper multiplexer in applications where there are

multiple I2C-bus devices with the same fixed address (for example, EEPROMs with

address of ‘Z’ as shown in Figure 25) connected in a multipoint arrangement to the same

I2C-bus. Up to 112 hot-swappable cards/devices can be multiplexed to the same bus

master by using one PCA9641 per card/device. Since each PCA9641 has its own unique

address (for example, ‘A’, ‘B’, ‘C’, and so on), the EEPROMs can be connected to the

master, one at a time, by connecting one PCA9641 (Master 0 position) while keeping the

rest of the cards/devices isolated (off position).

The alternative, shown with dashed lines, is to use a PCA9548A 1-to-8 channel switch on

the master card and run eight I2C-bus devices, one to each EEPROM card, to multiplex

the master to each card. The number of card pins used is the same in either case, but

there are seven fewer pairs of SDA/SCL traces on the printed-circuit board if the

PCA9641 is used.

Fig 25. Gatekeeper multiplexer application

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PCA9641BSHP Datasheet(PDF) 36 Page - NXP Semiconductors