MX8771

IXYS

The MX8771 responds to two different slave addresses. The first address can be set from 20h to 27h by

connecting pins A2, A1, A0 according to the table below and is used to write and read from the 16-bit

data register. The second address is fixed at 28h and facilitates the simultaneous update of outputs from

multiple bytes and multiple MX8771's. The contents of the data register are transferred to the buffer

register when the i2c master issues a read command to address 28h. The data byte that is read from 28h

is a dummy byte whose value is undefined. Optionally the master can terminate the read command after

issuing the address and the read bit without actually reading a byte.

A2

A1

A0

i2c slave address

0

0

0

20 (hex)

0

0

1

21

0

1

0

22

0

1

1

23

1

0

0

24

1

0

1

25

1

1

0

26

1

1

1

27

RSTN OE

All Outputs

0

0

Hi-Z

1

0

Hi-Z

0

1

GND

1

1

i2c control

For the following timing examples, pin A2 = high, A1 = high, A0 = low

Write two bytes to the MX8771 data register and then update the MX8771 buffer register:

address 26h, W

byte 1

byte 2

address 28h, R

stop here

-or-

stop

dummy read

SDA

7 6 5 4 3 2 1 0

7 6 5 4 3 2 1 0

SCL

OUT

ack (slave)

start

no ack (master)

start

ack (slave)

ack (slave)

stop

ack (slave)

Read two bytes from the MX8771 data register:

address 26h + R

byte 1

byte 2

no ack (master)

SDA

7 6 5 4 3 2 1 0

7 6 5 4 3 2 1 0

SCL

start

ack (slave)

ack (master)

stop

MX8771

4

3/6/08

Drawing No. 877109

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