ADE7858A Просмотр технического описания (PDF) - Analog Devices
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ADE7858A Datasheet PDF : 96 Pages
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Data Sheet
ADE7854A/ADE7858A/ADE7868A/ADE7878A
POWER MANAGEMENT
The ADE7868A/ADE7878A have four modes of operation and
the ADE7854A/ADE7858A have two modes of operation; the
modes of operation are determined by the state of the PM0 and
PM1 pins (see Table 9).
Table 9. Power Supply Modes
Power Supply Mode
PSM0, Normal Power Mode
PSM1, Reduced Power Mode1
PSM2, Low Power Mode1
PSM3, Sleep Mode
PM1 Pin
0
0
1
1
PM0 Pin
1
0
0
1
1 Available in the ADE7868A and ADE7878A only.
The PM1 and PM0 pins control the operation of the ADE7854A/
ADE7858A/ADE7868A/ADE7878A. These pins are easily con-
nected to an external microprocessor input/output. The PM1
and PM0 pins include internal pull-up resistors; therefore, the
ADE7854A/ADE7858A/ADE7868A/ADE7878A are in sleep
mode by default. For recommended actions to take before and
after setting a new power mode, see Table 11 and Table 12.
PSM0 NORMAL POWER MODE (ALL DEVICES)
In PSM0 normal power mode (PSM0 mode), the ADE7854A/
ADE7858A/ADE7868A/ADE7878A are fully functional. To
enter PSM0 mode, the PM1 pin is set low and the PM0 pin is
set high. When a device is in PSM1, PSM2, or PSM3 mode
and switches to PSM0 mode, all control registers revert to their
default values, except for the threshold register, LPOILVL
(which is used in PSM2 mode), and the CONFIG2 register.
These registers maintain their programmed values.
The ADE7854A/ADE7858A/ADE7868A/ADE7878A signal
the completion of the power-up procedure by driving the IRQ1
interrupt pin low and setting Bit 15 (RSTDONE) in the STATUS1
register to 1. Bit 15 is cleared to 0 during the power-up
sequence and is set to 1 when the chip enters PSM0 mode.
Writing to the STATUS1 register with the RSTDONE bit set to 1
clears the status bit and returns the IRQ1 pin high.
The RSTDONE interrupt cannot be masked because Bit 15
(RSTDONE) in the interrupt mask register has no functionality.
PSM1 REDUCED POWER MODE (ADE7868A AND
ADE7878A ONLY)
The PSM1 reduced power mode (PSM1 mode) is available
on the ADE7868A and ADE7878A only. In PSM1 mode, the
ADE7868A/ADE7878A measure the mean absolute values
(MAV) of the 3-phase currents and store the results in the
20-bit AIMAV, BIMAV, and CIMAV registers. PSM1 mode is
useful in missing neutral cases where an external battery
provides the voltage supply for the ADE7868A or ADE7878A.
The I2C or SPI serial port is enabled in PSM1 mode and can be
used to read the AIMAV, BIMAV, and CIMAV registers. Do not
read any other registers because their values are not guaranteed
in PSM1 mode. Similarly, a write operation in PSM1 mode is
ignored by the ADE7868A/ADE7878A. In PSM1 mode, do not
access any registers other than AIMAV, BIMAV, and CIMAV.
For more information about the xIMAV registers, see the
Current Mean Absolute Value Calculation—ADE7868A and
ADE7878A Only section.
The circuit that measures the estimates of rms values is also
active during PSM0 mode; therefore, the calibration of this
circuit can be done in either PSM0 mode or PSM1 mode. Note
that the ADE7868A and ADE7878A do not provide registers to
store or process the corrections resulting from the calibration
process. The external microprocessor stores the gain values
from these measurements and uses them during PSM1 mode.
The 20-bit mean absolute value measurements that are completed
in PSM1 mode are available in PSM0 mode. However, the MAV
values are different from the rms measurements of phase currents
and voltages that are executed only in PSM0 mode and stored in
the xIRMS and xVRMS 24-bit registers. For more information,
see the Current Mean Absolute Value Calculation—ADE7868A
and ADE7878A Only section.
If the ADE7868A/ADE7878A are set to PSM1 mode while
configured for PSM0 mode, the devices immediately begin the
mean absolute value calculations. The xIMAV registers are
accessible at any time; however, if the ADE7878A or ADE7868A
is set to PSM1 mode while configured for PSM2 or PSM3 mode,
the ADE7868A/ADE7878A signal the start of the mean absolute
value computations by driving the IRQ1 pin low. The xIMAV
registers can be accessed only after the IRQ1 pin is low.
PSM2 LOW POWER MODE (ADE7868A AND
ADE7878A ONLY)
The PSM2 low power mode (PSM2 mode) is available on the
ADE7868A and ADE7878A only. PSM2 mode reduces the power
consumption required to monitor the currents when there is no
voltage input, and an external battery provides the voltage supply
for the ADE7868A/ADE7878A.
PSM2 mode detects a missing neutral tamper condition by
monitoring all phase currents and comparing them with a
programmable threshold. If any phase current rises above the
programmable threshold for a programmable period, the device
assumes that a tamper attack has occurred. If all currents remain
below the programmable threshold, no tamper attack has taken
place; instead, a simple power outage has occurred.
When a missing neutral tamper condition occurs, the external
microprocessor sets the ADE7868A/ADE7878A to PSM1 mode,
measures the mean absolute values of the phase currents, and
integrates the energy based on these values and the nominal
voltage. The I2C or SPI port is not functional during this mode.
Rev. C | Page 21 of 96
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