Analog Devices LTM4683 Manual page 45

OPERATION
SDA
t
t
f
LOW
SCL
t
HD(STA)
START
CONDITION
Table 6. Abbreviations of Supported Data Formats
PMBus
SPECIFICATION
TERMINOLOGY REFERENCE
L11 Linear Part II ¶7.1
L16 Linear Part II ¶8.2
VOUT_MODE
CF DIRECT Part II ¶7.2
Reg Register Bits Part II ¶10.3
ASC Text Characters Part II ¶22.2.1
The following data formats are implemented by PMBus.
The main transmitter transmits to a subordinate
n
receiver. The transfer direction, in this case is
not changed.
The main transmitter reads the subordinate receiver
n
immediately after the first byte. At the moment of
the first acknowledgement (provided by the subor-
dinate receiver), the main transmitter becomes the
main receiver, and the subordinate receiver becomes
a subordinate transmitter.
Combined format. During a change of direction within
n
a transfer, the main device repeats both a start con-
dition and the subordinate device address but with
t
t
r
SU(DAT)
t
f
t
SU(STA)
t t
HD(DAT) HIGH
Figure 6. PMBus Timing Diagram
See Table 7 See Table 7 See Table 7
ADI
TERMINOLOGY DEFINITION
Linear_5s_1s Floating point 16-bit data: value = Y • 2
where N = b[15:11] and Y = b[10:0], both
two's compliment binary integers
Linear_16u Floating point 16-bit data: value = Y • 2
where Y = b[15:0], an unsigned integer
Varies 16-bit data with a custom format defined in
the detailed PMBus command description
Reg Per-bit meaning defined in detailed PMBus
command description
ASCII ISO/IEC 8859-1 [A05]
For more information
t t
HD(SDA) SP
t
REPEATED START
CONDITION
EXAMPLE
N
, b[15:0] = 0x9807 = 10011_000_0000_0111
value = 7 • 2
–12
, b[15:0] = 0x4C00 = 0100_1100_0000_0000
value = 19456 • 2
Often an unsigned or two's compliment
integer
PMBus STATUS_BYTE command
LTC (0x4C5443)
the R/W bit reversed. In this case, the main receiver
terminates the transfer by generating a NACK on the
last byte of the transfer and a STOP condition.
See Figure 7 for a legend.
Handshaking features are included to ensure robust sys-
tem communication. See the PMBus Communication and
Command Processing subsection of the Applications
Information section for further details.
FIGURE 7—FIGURE 24 PMBus PROTOCOLS
www.analog.com
LTM4683
t
r
t
BUF
SU(STO)
4683 F06
STOP START
CONDITION CONDITION
–13
= 854E-6
–12
= 4.75
Rev. 0
45