EVAL-ADM1276EBZ Analog Devices, EVAL-ADM1276EBZ Datasheet - Page 23

• 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
VOUT MEASUREMENT
The VOUT pin on the ADM1276 can be used to provide an
alternate voltage for the power monitor to measure. The user
can choose to measure the voltage at the SENSE+ pin or the
voltage at the VOUT pin, using either the low or high input
voltage range.
If the VOUT pin is to be used to measure the output voltage after
the FET, insert a 1 kΩ resistor in series between the source of
the FET and the VOUT pin. This resistor provides some separa-
tion between the ADM1276 and the FET source during a fault
condition; thus, ADM1276 operation is not affected.
FET HEALTH
The ADM1276 provides a method of detecting a shorted pass
FET. The FET health status can be used to generate an alert on
the GPO2/ ALERT2 pin. By default at power-up, an alert is gener-
ated on the GPO2/ ALERT2 pin of the ADM1276 when the FET
health status indicates that a bad FET is present. FET health is
considered bad if all of the following conditions are true:
•
•
•
POWER MONITOR
The ADM1276 features an integrated ADC that accurately meas-
ures the current sense voltage, the input voltage, and (optionally)
the output voltage. The measured input voltage and current being
delivered to the load are multiplied to give a power value that can
be read back. Each power value is also added to an accumulator
that can be read back to allow an external device to calculate the
energy consumption of the load.
The ADM1276 can report the measured current, input voltage,
and the output voltage. The PEAK_IOUT, PEAK_VIN, and
PEAK_VOUT commands can be used to read the highest peak
current or voltage since the value was last cleared.
An averaging function is provided for voltage and current that
allows a number of samples to be averaged by the ADM1276.
This function reduces the need for postprocessing of sampled
data by the host processor. The number of samples that can be
averaged is 2
The ADM1276 is holding the FET off, for example, during
the initial power-on cycle time.
V
V
SENSE
GATE
< ~1 V, that is, less than the FET gate threshold.
> 2 mV.
N
, where N is in the range of 0 to 7.
Rev. B | Page 23 of 48
The power monitor current sense amplifier is bipolar and can
measure both positive and negative currents. The power monitor
amplifier has an input range of ±25 mV.
Two input voltage ranges are available and can be selected using
the PMBus interface: 0 V to 6 V (low input range) and 0 V to
20 V (high input range).
The two basic modes of operation for the power monitor are
single shot and continuous. In single shot mode, the power
monitor samples the input voltage and current a number of
times, depending on the averaging value selected by the user.
The ADM1276 returns a single value corresponding to the
average voltage and current measured. When configured for
continuous mode, the power monitor continuously samples
voltage and current, making the most recent sample available
to be read.
The single shot mode can be triggered in a number of ways.
The simplest is by selecting the single shot mode using the
PMON_CONFIG command and writing to the convert bit
using the PMON_CONTROL command. The convert bit can
also be written as part of a PMBus group command. Using a
group command allows multiple devices to be written to as part
of the same I
command when the stop condition appears on the bus. In this
way, several devices can be triggered to sample at the same time.
Each time a current sense and input voltage measurements are
taken, a power calculation is performed, multiplying the two
measurements together. This can be read from the device using
the READ_PIN command, returning the input power.
At the same time, the calculated power value is added to a
power accumulator register, that may increment a rollover
counter if the value exceeds the maximum accumulator value,
and that also increments a power sample counter.
The power accumulator and power sample counter are read
using the same READ_EIN command to ensure that the
accumulated value and sample count are from the same point
in time. The bus host reading the data assigns a timestamp to
when the data is read. By calculating the time difference between
consecutive uses of READ_EIN, and determining the delta in
power consumed, it is possible for the host to determine the
total energy consumed over that period.
2
C bus transaction, with all devices executing the
ADM1276