ADE7880 View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'ADE7880' PDF : 104 Pages View PDF
Data Sheet
ADE7880
POWER MANAGEMENT
The ADE7880 has four modes of operation, determined by the
state of the PM0 and PM1 pins (see Table 8). These pins provide
complete control of the ADE7880 operation and can easily be
connected to an external microprocessor I/O. The PM0 and
PM1 pins have internal pull-up resistors. See Table 10 and Table 11
for a list of actions that are recommended before and after setting
a new power mode.
during PSM1 (see the Current Mean Absolute Value Calculation
section for more details on the xIMAV registers).
The 20-bit mean absolute value measurements done in PSM1,
although also available in PSM0, are different from the rms meas-
urements of phase currents and voltages executed only in PSM0
and stored in the HxIRMS and HxVRMS 24-bit registers. See
the Current Mean Absolute Value Calculation section for details.
Table 8. Power Supply Modes
Power Supply Modes
PSM0, Normal Power Mode
PSM1, Reduced Power Mode
PSM2, Low Power Mode
PSM3, Sleep Mode
PM1
PM0
0
1
0
0
1
0
1
1
PSM0—NORMAL POWER MODE (ALL PARTS)
In PSM0 mode, the ADE7880 is fully functional. For the ADE7880
to enter this mode, the PM0 pin is set to high, and the PM1 pin
is set to low. If the ADE7880 is in PSM1, PSM2, or PSM3 mode
and is switched into PSM0 mode, then all control registers take
the default values with the exception of the threshold register,
LPOILVL, which is used in PSM2 mode, and the CONFIG2
register, both of which maintain their values.
The ADE7880 signals the end of the transition period by triggering
the IRQ1 interrupt pin low and setting Bit 15 (RSTDONE) in the
STATUS1 register to 1. This bit is 0 during the transition period
and becomes 1 when the transition is finished. The status bit is
cleared and the IRQ1 pin is set back to high by writing to the
STATUS1 register with the corresponding bit set to 1. Bit 15
(RSTDONE) in the interrupt mask register does not have any
functionality attached even if the IRQ1 pin goes low when Bit 15
(RSTDONE) in the STATUS1 register is set to 1. This makes the
RSTDONE interrupt unmaskable.
PSM1—REDUCED POWER MODE
In the reduced power mode, PSM1, the ADE7880 measures the
mean absolute values (mav) of the 3-phase currents and stores
the results in the AIMAV, BIMAV, and CIMAV 20-bit registers.
This mode is useful in missing neutral cases in which the voltage
supply of the ADE7880 is provided by an external battery. The
serial ports, I2C or SPI, are enabled in this mode; the active port
can be used to read the AIMAV, BIMAV, and CIMAV registers.
Do not read any of the other registers as their values are not
guaranteed in this mode. Similarly, the ADE7880 does not take a
write operation into account by in this mode.
If the ADE7880 is set in PSM1 mode after being in PSM0 mode,
the ADE7880 begins the mean absolute value calculations without
any delay. The xIMAV registers are accessible at any time; however,
if the ADE7880 is set in PSM1 mode after being in PSM2 or
PSM3 modes, the ADE7880 signals the start of the mean absolute
value computations by triggering the IRQ1 pin low. The xIMAV
registers can be accessed only after this moment.
PSM2—LOW POWER MODE
In the low power mode, PSM2, the ADE7880 compares all
phase currents against a threshold for a period of 0.02 ×
(LPLINE[4:0] + 1) seconds, independent of the line frequency.
LPLINE[4:0] are Bits[7:3] of the LPOILVL register (see Table 9).
Table 9. LPOILVL Register
Bit Mnemonic Default
[2:0] LPOIL[2:0] 111
[7:3] LPLINE[4:0] 00000
Description
Threshold is put at a value
corresponding to full scale
multiplied by LPOIL/8
The measurement period is
(LPLINE[4:0] + 1)/50 sec
The threshold is derived from Bits[2:0] (LPOIL[2:0]) of the
LPOILVL register as LPOIL[2:0]/8 of full scale. Every time
one phase current becomes greater than the threshold, a
counter is incremented. If every phase counter remains below
LPLINE[4:0] + 1 at the end of the measurement period, then
the IRQ0 pin is triggered low. If a single phase counter becomes
greater or equal to LPLINE[4:0] + 1 at the end of the measurement
period, the IRQ1 pin is triggered low. Figure 33 illustrates how
the ADE7880 behaves in PSM2 mode when LPLINE[4:0] = 2
and LPOIL[2:0] = 3. The test period is three 50 Hz cycles (60 ms),
and the Phase A current rises above the LPOIL[2:0] threshold three
times. At the end of the test period, the IRQ1 pin is triggered low.
LPLINE[4:0] = 2
IA CURRENT
LPOIL[2:0]
THRESHOLD
In summary, in this mode, it is not recommended to access any
register other than AIMAV, BIMAV, and CIMAV. The circuit
that computes the rms estimates is also active during PSM0;
therefore, its calibration can be completed in either PSM0 mode
or in PSM1 mode. Note that the ADE7880 does not provide any
PHASE
PHASE
PHASE
COUNTER = 1 COUNTER = 2 COUNTER = 3
register to store or process the corrections resulting from the
calibration process. The external microprocessor stores the gain
values in connection with these measurements and uses them
IRQ1
Figure 33. PSM2 Mode Triggering IRQ Pin for LPLINE[4:0] = 2 (50 Hz Systems)
Rev. C | Page 21 of 107
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