ADE7758_15 datasheet(37/72 Pages) AD

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Data Sheet

ADE7758

Rev. E | Page 37 of 72

Similar to reactive power, the fastest integration time occurs

when the VAR gain registers are set to maximum full scale,

that is, 0x7FF. The time it takes before overflow can be scaled

by writing to the VARDIV register; and, therefore, it can be

increased by a maximum factor of 255.

By setting the REHF bit (Bit 1) of the interrupt mask register,

the ADE7758 can be configured to issue an interrupt (IRQ)

when Bit 14 of any one of the three VAR-hr accumulation

registers has changed, indicating that the accumulation register

is half full (positive or negative).

When overflow occurs, the VAR-hr accumulation registers

content can rollover to full-scale negative (0x8000) and continue

increasing in value when the reactive power is positive. Con-

versely, if the reactive power is negative, the VAR-hr accumulation

registers content can roll over to full-scale positive (0x7FFF)

and continue decreasing in value.

Setting the RSTREAD bit (Bit 6) of the LCYMODE register

enables a read-with-reset for the VAR-hr accumulation

registers; that is, the registers are reset to 0 after a read

operation.

VARG[11:0]

VARDIV[7:0]

90° PHASE

SHIFTING FILTER

MULTIPLIER

HPF

CURRENT SIGNAL–i(t)

0x2851EC

0x00

0xD7AE14

VOLTAGE SIGNAL–v(t)

0x2852

0x00

0xD7AE

LPF2

SIGN 26

20 2–1 2–2 2–3 2–4

VAROS[11:0]

VARHR[15:0]

TOTAL REACTIVE POWER IS

ACCUMULATED (INTEGRATED) IN

THE VAR-HR ACCUMULATION REGISTERS

PHCAL[6:0]

Figure 73. ADE7758 Reactive Energy Accumulation

ADE7758 Datasheet(PDF) 37 Page - Analog Devices

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