PCA9525

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© NXP B.V. 2011. All rights reserved.

Product data sheet

Rev. 1 — 25 February 2011

12 of 22

NXP Semiconductors

PCA9525

Simple 2-wire bus buffer

Multiplexers such as the PCA9544A are simple analog switches which provide no

capacitive load isolation between connected branches. Figure 16 shows the PCA9525

branch. Figure 17 and Figure 18 show alternate forms of bus multiplexing, with the latter

being an excellent way to eliminate the requirement for a master to dedicate pins to

enabling multiple PCA9525 devices.

Fig 15. PCA9525 with masters on both sides of buffer

Alternately, using the PCA9546A, (which allows multiple outputs to be selected) you would simply

place a PCA9525 on each output on the right hand side, rather than a single PCA9525 on the

left hand side.

Fig 16. PCA9525 multiplexer isolation application

002aaf343

BUS MASTER

U2

SCL

SDA

R1

R2

R3

R4

SCL

SDA

SCL_IN

SDA_IN

PCA9525

SCL_OUT

SDA_OUT

U1

EN

DIR

5 V

IRQ

MASTER/

SLAVE

U3

MASTER

U4

SLAVE

U5

master U4 requests SCL

direction change from

master U2 using IRQ

002aaf344

BUS MASTER

U1

SCL

SDA

R1

1.5 k

Ω

R2

1.5 k

Ω

R3

1.1 k

Ω

R4

1.1 k

Ω

3.3 V

SCL

SDA

PCA9544A

SC0

SD0

U3

INT[3:0]

A0

A1

A2

SC1

SD1

SC2

SD2

SC3

SD3

Using the PCA9525,

up to 400 pF may be

connected to each

and every bus 0

through bus 3.

SCL_IN

SDA_IN

PCA9525

SCL_OUT

SDA_OUT

U2

EN

DIR