EVAL-ADM1276EBZ Analog Devices, EVAL-ADM1276EBZ Datasheet - Page 29

• Manufacturer Part Number: EVAL-ADM1276EBZ
• Description: Power Management IC Development Tools EVALUATION BOARD
• Manufacturer: Analog Devices
• Type: Hot Swap & Power Distributionr
• Series: ADM1276r

Specifications of EVAL-ADM1276EBZ

• Rohs: yes
• Tool Is For Evaluation Of: ADM1276
• Input Voltage: 20 V
• Factory Pack Quantity: 1

Data Sheet
The power monitor can measure the following quantities:
•
•
•
The following quantities are then calculated:
•
•
PMON_CONFIG Command
The power monitor can run in a number of different modes with
different input voltage range settings. The PMON_CONFIG
command is used to set up the power monitor.
The settings that can be configured are as follows:
•
•
•
•
Modifying the power monitor settings while the power monitor
is sampling is not recommended. To ensure correct operation of
the device and to avoid any potential spurious data or the
generation of status alerts, stop the power monitor before any of
these settings are changed.
PMON_CONTROL Command
Power monitor sampling can be initiated via hardware or via
software using the PMON_CONTROL command. This command
can be used with single shot or continuous mode.
READ_VIN, READ_VOUT, and READ_IOUT Commands
The ADM1276 power monitor measures the voltage developed
across the sense resistor to provide a current measurement. The
input voltage from the SENSE+ pin is always measured, and the
output voltage present on the VOUT pin is available if enabled
with the PMON_CONFIG command.
READ_PIN, READ_PIN_EXT, READ_EIN, and
READ_EIN_EXT Commands
The 12-bit VIN input voltage and 12-bit IOUT current measure-
ment values are multiplied by the ADM1276 to give the input
power value. This is accomplished by using fixed point
arithmetic, and produces a 24-bit value. It is assumed that the
numbers are in the 12.0 format, meaning that there is no
fractional part. Note that only positive IOUT values are used to
avoid returning a negative power.
This 24-bit value can be read from the ADM1276 using the
READ_PIN_EXT command, where the most significant bit
(MSB) is always a zero because PIN_EXT is a twos complement
binary value that is always positive.
The sixteen most significant bits of the 24-bit value are used as
the value for PIN. The MSB of the 16-bit PIN word is always
zero, as PIN is a twos complement binary value, that is always
positive.
Input voltage (VIN).
Output voltage (VOUT).
Output current (IOUT).
Input power (PIN).
Input energy (EIN).
Single shot or continuous sampling.
VOUT sampling enable/disable.
Voltage input range.
Current and voltage sample averaging.
Rev. B | Page 29 of 48
Each time a power calculation is done, the 24-bit power value is
added to a 24-bit energy accumulator register. This is a twos
complement representation as well, so the MSB is always zero.
Each time this energy accumulator register rolls over from
0x7FFFFF to 0x000000, a 16-bit rollover counter is
incremented. The rollover counter is straight binary, with a
maximum value of 0xFFFF before it rolls over.
A 24-bit straight binary power sample counter is also
incremented by 1 each time a power value is calculated and
added to the energy accumulator.
These registers can be read back using one of two commands,
depending on the level of accuracy required for the energy
accumulator and the desire to limit the frequency of reads from
the ADM1276.
A bus host can read these values, and by calculating the delta in
the energy accumulated, the delta in the number of samples,
and the time delta since the last read, the host can calculate the
average power since the last read, as well as the energy
consumed since then.
The time delta is calculated by the bus host based on when it
sends its commands to read from the device, and is not
provided by the ADM1276.
To avoid loss of data, the bus host must read at a rate that
ensures the rollover counter does not wrap around more than
once, and if the counter does wrap around that the next value
read for PIN is less than the previous one.
The READ_EIN command returns the top 16 bits of the energy
accumulator, the lower eight bits of the rollover counter, and the
full 24 bits of the sample counter.
The READ_EIN_EXT command returns the full 24 bits of the
energy accumulator, the full 16 bits of the rollover counter, and
the full 24 bits of the sample counter. The use of the longer
rollover counter means that the time interval between reads of
the part can be increased from seconds to minutes, without
losing any data.
PEAK_IOUT, PEAK_VIN, PEAK_VOUT, and PEAK_PIN
Commands
In addition to the standard PMBus commands for reading
voltage and current, the ADM1276 provides commands that
can report the maximum peak voltage, current, or power value
since the peak value was last cleared.
The peak values are updated only after the power monitor has
sampled and averaged the current and voltage measurements.
Individual peak values are cleared by writing a 0 value with the
corresponding command.
WARNING LIMIT SETUP COMMANDS
The ADM1276 power monitor can monitor a number of
different warning conditions simultaneously and report any
current or voltage values that exceed the user-defined
thresholds using the status commands.
ADM1276