Rev 1.6

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09/2016

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PI3749-x0

three level inputs, providing nine possible combination pairs, although only eight of these combinations are unique, as shown in table 3.

Considering only the 7 bit address sub-field, the high-order address bits <6> through <4> are hardcoded to 4’b1001, while the lower order

address bits <3> through <0> are modified by the ADRx pins.

Note that the state of the ADRx pins is resolved on each I2C address transfer. Therefore the PI3749-20 address can be changed while the

regulator is powered up and in operation.

Depending on the state of the read/write bit, two types of transfers are possible:

a. Write: Data transferred from the I2C master to the PI3749-20 slave

The first byte is transmitted by the master and includes the slave address and the R/W bit set to write (as shown in the last column of table 3.)

The second byte is also transmitted by the master and is the write data.

The slave responds between each byte with an acknowledge bit.

b. Read: Data returned from the PI3749-20 slave to the master

The first byte is transmitted by the master and includes the slave address but the R/W bit is set to read. The slave responds to the first

byte (the address transmitted by the master) with an acknowledge bit.

The second byte is transmitted by the slave back to the master and is the read data. The master responds after the read data byte

with a not-acknowledge bit (since the PI3749-20 read data are all single byte registers).

ADDRx state

Sub-field bit positions <7.1>

Fully formed address write word

(including lsb of the transfer set for a write)

ADR1

ADR0

Hexadecimal

Decimal

Binary

Binary

L

L

7’h48

72

7’b100_1000

8’b1001_0001

L

M

7’h49

73

7’b100_1001

8’b1001_0011

L

H

7’h4A

74

7’b100_1010

8’b1001_0101

M

L

7’h4B

75

7’b100_1011

8’b1001_0111

M

M

7’h4C

76

7’b100_1100

8’b1001_1001

M

H

7’h4D

77

7’b100_1101

8’b1001_1011

H

L

7’h4E

78

7’b100_1110

8’b1001_1101

H

M

7’h4F

79

7’b100_1111

8’b1001_1111

H

H

7’h4F

79

7’b100_1111

8’b1001_1111