Datasheet
The Snapshot feature enables the user to read the parameters via
the PMBus interface during normal operation, although it should be
noted that reading the 22 bytes will occupy the bus for some time.
The Snapshot enables the user to store the snapshot parameters to
Flash memory in response to a pending fault as well as to read the
stored data from Flash memory after a fault has occurred. Automatic
store to Flash memory following a fault is triggered when any fault
threshold level is exceeded, provided that the specifi c fault response
is to shut down. Writing to Flash memory is not allowed if the device
is confi gured to restart following the specifi c fault condition. It should
also be noted that the device supply voltage must be maintained
during the time the device is writing data to Flash memory; a process
that requires between 700-1400 s depending on whether the data
is set up for a block write. Undesirable results may be observed if the
input voltage of the product drops below 3.0 V during this process.
Non-Volatile Memory (NVM)
The product incorporates two Non-Volatile Memory areas for storage of
the supported PMBus commands; the Default NVM and the User NVM.
The Default NVM is pre-loaded with Murata factory default
values. The Default NVM is write-protected and can be used to
restore the Murata factory default values through the command
RESTORE_DEFAULT_ALL.
The User NVM is pre-loaded with Murata factory default values. The
User NVM is writable and open for customization. The values in NVM
are loaded into operational RAM during initialization according to sec-
tion “Initialization Procedure”, where after commands can be changed
through the PMBus Interface. The STORE_USER_ALL command will
store the changed parameters to the User NVM.
Software tools for design and production
Murata provides software tools for confi guration and monitoring of
this product via the PMBus interface. For more information please
contact your local Murata sales representative.
PMBus addressing
The PMBus address should be confi gured with resistors connected
between the SA0/SA1 pins and the PREF pin, as shown in the
PMBus interface
This product provides a PMBus digital interface that enables the user
to confi gure many aspects of the device operation as well as to moni-
tor the input and output voltages, output current and device tem-
perature. The product can be used with any standard two-wire I
2
C or
SMBus host device. In addition, the product is compatible with PMBus
version 1.1 and includes an SALERT line to help mitigate bandwidth
limitations related to continuous fault monitoring. The product sup-
ports 100 kHz bus clock frequency only. The PMBus signals, SCL, SDA
and SALERT require passive pull-up resistors as stated in the SMBus
Specifi cation. Pull-up resistors are required to guarantee the rise time
as follows:
Eq. 6. = R
p
C
p
≤ 1µs,
where R
p
is the pull-up resistor value and C
p
is the bus loading, the
maximum allowed bus load is 400 pF. The pull-up resistor should be
tied to an external supply voltage in range from 2.7 to 5.5 V, which
should be present prior to or during power-up. If the proper power
supply is not available, voltage dividers may be applied. Note that in
this case, the resistance in the equation above corresponds to parallel
connection of the resistors forming the voltage divider.
Monitoring via PMBus
It is possible to monitor a wide variety of parameters through the
PMBus interface. Fault conditions can be monitored using the SALERT
pin, which will be asserted when any number of pre-confi gured fault
or warning conditions occurs. It is also possible to continuously moni-
tor one or more of the power conversion parameters including but not
limited to the following:
Input voltage (READ_VIN)
Output voltage (READ_VOUT)
Output current (READ_IOUT)
Internal junction temperature (READ_TEMPERATURE_1)
Switching frequency (READ_FREQUENCY)
Duty cycle (READ_DUTY_CYCLE)
In the default confi guration monitoring is enabled also when the
output voltage is disabled. This can be changed in order to reduce
standby power consumption.
Snap shot parameter capture
This product offers a special feature that enables the user to capture
parametric data during normal operation or following a fault. The fol-
lowing parameters are stored:
Input voltage
Output voltage
Output current
Internal junction temperature
Switching frequency
Duty cycle
Status registers
User NVM
Factory default
Customizable
RAM
RESTORE_DEFAULT_ALL
Default NVM
Factory default
Write-protected
READ
WRITE
PMBus interface
STORE_USER_ALL
INITIALIZATION
INITIALIZATION
RESTORE USER ALL
OKDx-T/50-W12-C
50A Digital PoL DC-DC Converter Series
MDC_OKDx-T/50-W12-C.A04 Page 32 of 41
www.murata-ps.com/support