ncp4201 ON Semiconductor, ncp4201 Datasheet - Page 18

• Manufacturer Part Number: ncp4201
• Description: Ncp4201 Programmable Multi-phase Synchronous Buck Converter With Pmbus
• Manufacturer: ON Semiconductor

Write Operations
different types of read and writes operations. The ones used
in the NCP4201 are discussed in this section. The following
abbreviations are used in the diagrams:
S—START
P—STOP
R—READ
W—WRITE
A—ACKNOWLEDGE
A—NO ACKNOWLEDGE
The NCP4201 uses the following PMBus write protocols.
The PMBus specification defines several protocols for
REPEATED
START BY
SDA
MASTER
SCL
SDA
SCL
START BY
MASTER
SDA
SCL
SDA
SCL
1
1
START BY
1
1
MASTER
START BY
MASTER
SERIAL BUS ADDRESS BYTE
1
1
1
1
SERIAL BUS ADDRESS BYTE
0
0
1
1
FRAME 1
1
SERIAL BUS ADDRESS BYTE
0
FRAME 1
1
0
SERIAL BUS ADDRESS BYTE
0
0
0
0
FRAME 1
0
Figure 12. Write Byte
Figure 13. Read Byte
Figure 11. Send Byte
FRAME 1
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0
A1
A1
SDA (CONTINUED)
0
SCL (CONTINUED)
0
A0
A0
A1
18
A1
NCP4201
ACK. BY
R/W
R/W
A0
Send Byte
command byte to a slave device as follows:
NCP4201
ACK. BY
A0
R/W
In this operation, the master device sends a single
9
9
R/W
NCP4201
ACK. BY
1. The master device asserts a start condition on
2. The master sends the 7−bit slave address followed
3. The addressed slave device asserts ACK on SDA.
4. The master sends a command code.
5. The slave asserts ACK on SDA.
6. The master asserts a stop condition on SDA and
NCP4201
ACK. BY
SDA.
by the write bit (low).
the transaction ends.
9
D7
D7
1
1
D7
1
9
D7
1
D6
D6
D7
D6
1
D6
DATA BYTE FROM NCP4201
D5
D5
D6
D5
D5
D5
D4
D4
D4
FRAME 2
COMMAND CODE
COMMAND CODE
DATA BYTE
D4
FRAME 2
FRAME 3
COMMAND CODE
D4
FRAME 2
D3
D3
D3
D3
FRAME 2
D3
D2
D2
D2
D2
D2
D1
D1
D1
D1
D0
D1
NCP4201
ACK. BY
D0
D0
NO ACK. BY
D0
MASTER
D0
9
NCP4201
NCP4201
ACK. BY
ACK. BY
NCP4201
9
ACK. BY
9
9
9
STOP BY
MASTER
STOP BY
MASTER
STOP BY
MASTER