NCP4200 Datasheet, PDF (18/32 Pages) ON Semiconductor – Programmable Multi-Phase Synchronous Buck Converter with PMBus

NCP4200
1
9
1
9
SCL
SDA
1
START BY
MASTER
1
0
0
0 _{A1 A0} R/W
D7 D6 D5 D4 D3 D2 D1 D0
ACK. BY
NCP4200
ACK. BY STOP BY
NCP4200 MASTER
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
COMMAND CODE
Figure 11. Send Byte
1
9
1
9
SCL
SDA
1
START BY
MASTER
1
0
0
0 _{A1 A0} R/W
D7 D6 D5 D4 D3 D2 D1 D0
ACK. BY
NCP4200
ACK. BY
NCP4200
FRAME 1
SERIAL BUS ADDRESS BYTE
FRAME 2
COMMAND CODE
1
9
SCL (CONTINUED)
1
SCL
SDA (CONTINUED)
D7 D6 D5 D4 D3 D2 D1 D0
FRAME 3
DATA BYTE
ACK. BY STOP BY
NCP4200 MASTER
Figure 12. Write Byte
9
1
9
SDA
1
START BY
MASTER
1
SCL
1
0
0
0 _{A1 A0} R/W
D7
ACK. BY
NCP4200
FRAME 1
SERIAL BUS ADDRESS BYTE
9
1
D6 D5
D4 D3 D2 D1
FRAME 2
COMMAND CODE
D0
ACK. BY
NCP4200
9
SDA
REPEATED
START BY
MASTER
11
0
0
0
A1 A0 R/W
ACK. BY
NCP4200
FRAME 1
SERIAL BUS ADDRESS BYTE
D7 D6 D5 D4 D3 D2 D1 D0
NO ACK. BY STOP BY
MASTER MASTER
FRAME 2
DATA BYTE FROM NCP4200
Figure 13. Read Byte
Write Operations
The PMBus specification defines several protocols for
different types of read and writes operations. The ones used
in the NCP4200 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 NCP4200 uses the following PMBus write protocols.
Send Byte
In this operation, the master device sends a single
command byte to a slave device as follows:
1. The master device asserts a start condition on
SDA.
2. The master sends the 7−bit slave address followed
by the write bit (low).
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
the transaction ends.
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