<s>
The	O
Power	B-Algorithm
Management	I-Algorithm
Bus	I-Algorithm
(	O
PMBus	B-Algorithm
)	O
is	O
a	O
variant	O
of	O
the	O
System	B-Algorithm
Management	I-Algorithm
Bus	I-Algorithm
(	O
SMBus	B-Algorithm
)	O
which	O
is	O
targeted	O
at	O
digital	O
management	O
of	O
power	O
supplies	O
.	O
</s>
<s>
Like	O
SMBus	B-Algorithm
,	O
it	O
is	O
a	O
relatively	O
slow	O
speed	O
two	O
wire	O
communications	O
protocol	O
based	O
on	O
I²C	O
.	O
</s>
<s>
The	O
first	O
part	O
gives	O
an	O
overview	O
with	O
particular	O
reference	O
to	O
SMBus	B-Algorithm
,	O
while	O
the	O
second	O
part	O
goes	O
into	O
detail	O
about	O
all	O
the	O
commands	O
defined	O
for	O
PMBus	B-Algorithm
devices	O
.	O
</s>
<s>
Conformance	O
requirements	O
for	O
PMBus	B-Algorithm
are	O
minimal	O
,	O
and	O
are	O
described	O
in	O
Part	O
I	O
of	O
the	O
specification	O
.	O
</s>
<s>
See	O
the	O
PMBus	B-Algorithm
1.1	O
specification	O
for	O
full	O
details	O
.	O
</s>
<s>
At	O
the	O
lowest	O
level	O
,	O
PMBus	B-Algorithm
follows	O
SMBus	B-Algorithm
1.1	O
with	O
a	O
few	O
differences	O
.	O
</s>
<s>
This	O
information	O
is	O
presented	O
in	O
more	O
detail	O
in	O
Part	O
I	O
of	O
the	O
PMBus	B-Algorithm
specification	O
:	O
</s>
<s>
In	O
PMBus	B-Algorithm
,	O
blocks	O
may	O
include	O
up	O
to	O
255	O
bytes	O
(	O
vs	O
.	O
the	O
32	O
byte	O
limit	O
of	O
SMbus	B-Algorithm
)	O
.	O
</s>
<s>
As	O
in	O
SMBus	B-Algorithm
2.0	O
,	O
only	O
seven	O
bit	O
addressing	O
is	O
used	O
.	O
</s>
<s>
Some	O
commands	O
use	O
the	O
SMBus	B-Algorithm
2.0	O
block	O
process	O
calls	O
.	O
</s>
<s>
Either	O
the	O
SMBALERT#	O
mechanism	O
or	O
the	O
SMBus	B-Algorithm
2.0	O
host	O
notify	O
protocol	O
may	O
be	O
used	O
to	O
notify	O
the	O
host	O
about	O
faults	O
.	O
</s>
<s>
PMBus	B-Algorithm
devices	O
are	O
required	O
to	O
support	O
a	O
Group	O
Protocol	O
,	O
where	O
devices	O
defer	O
acting	O
on	O
commands	O
until	O
they	O
receive	O
a	O
terminating	O
STOP	O
.	O
</s>
<s>
Since	O
commands	O
can	O
be	O
issued	O
to	O
many	O
different	O
devices	O
before	O
that	O
STOP	O
,	O
this	O
lets	O
the	O
PMBus	B-Algorithm
master	O
synchronize	O
their	O
actions	O
.	O
</s>
<s>
The	O
PMBus	B-Algorithm
command	O
space	O
can	O
be	O
seen	O
as	O
exposing	O
a	O
variety	O
of	O
readable	O
,	O
and	O
often	O
writable	O
,	O
device	O
attributes	O
such	O
as	O
measured	O
voltage	O
and	O
current	O
levels	O
,	O
temperatures	O
,	O
fan	O
speeds	O
,	O
and	O
more	O
.	O
</s>
<s>
The	O
ability	O
to	O
query	O
a	O
PMBus	B-Algorithm
1.1	O
device	O
about	O
its	O
capabilities	O
may	O
be	O
particularly	O
useful	O
when	O
building	O
tools	O
,	O
especially	O
in	O
conjunction	O
with	O
the	O
ability	O
to	O
store	O
user	O
data	O
in	O
the	O
devices	O
(	O
e.g.	O
</s>
<s>
in	O
EEPROM	B-General_Concept
)	O
.	O
</s>
<s>
Part	O
II	O
of	O
the	O
PMBus	B-Algorithm
specification	O
covers	O
every	O
standard	O
PMBus	B-Algorithm
command	O
.	O
</s>
<s>
PMBus	B-Algorithm
defines	O
its	O
own	O
16-bit	O
floating	O
point	O
format	O
,	O
termed	O
"	O
Linear11	O
"	O
.	O
</s>
<s>
Because	O
the	O
mantissa	O
is	O
a	O
signed	O
number	O
,	O
Linear11	O
does	O
not	O
have	O
a	O
representation	O
for	O
negative	O
zero	O
,	O
and	O
it	O
requires	O
an	O
11-bit	O
Two	B-General_Concept
's	I-General_Concept
complement	I-General_Concept
operation	O
to	O
invert	O
the	O
sign	O
.	O
</s>
<s>
In	O
January	O
2008	O
,	O
Power-One	O
was	O
awarded	O
a	O
win	O
in	O
a	O
patent	O
infringement	O
suit	O
between	O
them	O
and	O
Artesyn	O
Technologies	O
for	O
the	O
latter	O
's	O
PMBus	B-Algorithm
enabled	O
converters	O
.	O
</s>
<s>
Power-One	O
claims	O
that	O
PMBus	B-Algorithm
applications	O
need	O
a	O
license	O
from	O
them	O
.	O
</s>
<s>
Potential	O
PMBus	B-Algorithm
users	O
should	O
investigate	O
the	O
issue	O
for	O
themselves	O
.	O
</s>
