Datasheet

ADP5520
Rev. A | Page 20 of 40
COMMUNICATION INTERFACE
Communication to the ADP5520 is done via its I
2
C-compatible
serial interface. Figure 48 shows a typical write sequence for
programming an internal register.
1.
The cycle begins with a start condition, followed by the
chip write address (0x64).
2.
The ADP5520 acknowledges the chip write address byte by
pulling the data line low.
3.
The address of the register to which data is to be written is
sent next.
4.
The ADP5520 acknowledges the register address byte by
pulling the data line low.
5.
The data byte to be written is sent next.
6.
The ADP5520 acknowledges the data byte by pulling the
data line low.
7.
A stop condition completes the sequence.
Figure 49 shows a typical read sequence for reading back an
internal register.
1.
The cycle begins with a start condition, followed by the
chip write address (0x64).
2.
The ADP5520 acknowledges the chip write address byte by
pulling the data line low.
3.
The address of the register from which data is to be read is
sent next.
4.
The ADP5520 acknowledges the register address byte by
pulling the data line low.
5.
The cycle continues with a repeat start, followed by the
chip read address (0x65).
6.
The ADP5520 acknowledges the chip read address byte by
pulling the data line low.
7.
The ADP5520 places the contents of the previously
addressed register on the bus for readback.
8.
There is a no acknowledge following the readback data
byte, and the cycle is completed with a stop condition.
07445-037
10101000 000
CHIP ADDRESS
REGISTER ADDRESS ADP5520 RECEIVES DATA
0 = WRITE
ST SP
ADP5520 ACK ADP5520 ACK ADP5520 ACK
Figure 48. I
2
C Write Sequence
07445-038
10101000 1 010100000
CHIP ADDRESS REGISTER ADDRESS CHIP ADDRESS ADP5520 SENDS DATA
0 = WRITE
1 = READ
ST ST
1
SP
ADP5520 ACK ADP5520 ACK ADP5520 ACK
NO ACK
Figure 49. I
2
C Read Sequence