LP39542 Datasheet, PDF (33/58 Pages) National Semiconductor (TI) – Advanced Lighting Management Unit

Register changes take an effect at the SCL rising edge during the last ACK from slave.
w = write (SDA = “0”)
r = read (SDA = “1”)
ack = acknowledge (SDA pulled down by either master or slave)
rs = repeated start
id = 7-bit chip address, 54H (ADDR_SEL=0) or 55H (ADDR_SEL=1) for LP39542.
I²C Write Cycle
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When a READ function is to be accomplished, a WRITE function must precede the READ function, as shown in the Read Cycle
waveform.
I²C Read Cycle
I²C Timing Diagram
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