Ltpowerplay: An Interactive Gui For Digital Power; Pmbus Communication And Command Processing - Analog Devices LTM4683 Manual

APPLICATIONS INFORMATION
final configuration can be quickly developed and stored
in the LTM4683 EEPROM. Figure 30 illustrates the appli-
cation schematic for powering, programming and com-
munication with one or more LTM4683s via the ADI I
SMBus/PMBus adapter regardless of whether or not sys-
tem power is present. If system power is not present, the
dongle will power the LTM4683 through the V
supply pin. To initialize the part when V
and the V pin is powered, use global address 0x5B
DD33_nn
command 0xBD data 0x2B followed by address 0x5B
command 0xBD data 0xC4. The LTM4683 can now com-
municate with the internal EEPROM and read the project
file. To write the updated project file to the NVM, issue a
STORE_USER_ALL command. When V
MFR_RESET must be issued to allow the PWM POWER
to be enabled and valid ADCs to be read.
Because of the adapter's limited current sourcing capabil-
ity, only the LTM4683s, their associated pull-up resistors,
2
and the I C pull-up resistors should be powered from the
V 3.3V supply. In addition, any device sharing the I
DD33
bus connections with the LTM4683 should not have body
diodes between the SDA/SCL pins and their respective
V node because this will interfere with bus communica-
DD
tion without system power. If V
will not supply the power to the LTM4683s on the board.
It is recommended that the RUNn pins be held low or no
voltage configuration resistors inserted to avoid providing
power to the load until the part is fully configured.
The LTM4683 is fully isolated from the host PC's ground
by the DC1613A. The 3.3V from the adapter and the
LTM4683 V pin must be driven to each LTM4683
DD33_nn
internal controller with a separate PFET. If both V
V are not on, the V
BIAS DD33_nn
because the on-chip LDO is off. The controller's 3.3V
current limit is 100mA, but typical V
under 15mA. The V
DD33_nn
V pin. Normally, this is not an issue if V
BIAS
LTpowerPlay: AN INTERACTIVE GUI FOR
DIGITAL POWER
The LTpowerPlay (see Figure 31) is a powerful Windows-
based development environment that supports Analog
DD33_nn
is not applied,
INnn
is applied, an
IN
is applied, the DC1613A
IN
and
IN
pins can be in parallel
currents are
DD33_nn
does back drive the INTV
is open.
IN
For more information
Devices, Inc's digital power system management ICs,
including the LTM4683. The software supports a vari-
ety of different tasks. LTpowerPlay can evaluate Analog
2
C/
Devices, Inc's ICs by connecting to a demo board or the
user application. LTpowerPlay can also be used in an
offline mode (with no hardware present) to build mul-
tiple IC configuration files that can be saved and reloaded
later. LTpowerPlay provides unprecedented diagnostic and
debug features. It becomes a valuable diagnostic tool
during board bring-up to program or tweak the power
system or to diagnose power issues when bring up rails.
LTpowerPlay utilizes Analog Devices, Inc's USB-to-I
SMBus/PMBus adapter to communicate with one of the
many potential targets, including the DC2924A,
demo boards, or a customer target system. The software
also provides an automatic update feature to keep the
revisions current with the latest set of device drivers
and documentation.
A great deal of context-sensitive help is available with
2
C
LTpowerPlay, along with several tutorial demos.
PMBus COMMUNICATION AND COMMAND
PROCESSING
The LTM4683 internal controllers have a one-deep buf-
fer to hold the last data written for each supported com-
mand before processing, as shown in Figure 32, write
command data processing. When the part receives a new
command from the bus, it copies the data into the write
command data buffer, indicates to the internal processor
that this command data needs to be fetched, and con-
verts the command to its internal format so that it can be
executed. Two distinct parallel blocks manage command
buffering and command processing (fetch, convert, and
execute) to ensure the last data written to any command
is never lost. Command data buffering handles incoming
/
CC
PMBus writes by storing the command data in the write
command data buffer and marking these commands for
future processing. The internal processor runs in parallel
and handles the sometimes slower task of fetching, con-
verting and executing commands marked for processing.
Some computationally intensive commands (e.g., timing
parameters, temperatures, voltages and currents) have
internal processor execution times that may be long
www.analog.com
LTM4683
2
C/
DC3082A
Rev. 0
65