71M6515H
Energy Meter IC
DATA SHEET
MARCH 2008
Example: The register IRMS_C reads the value 2,079,670. Assuming IMAX to be 208A, and using the formula
above, we determine the RMS current of phase C to:
6.8781⋅10−9 208
IRMS = 2079670 ⋅
= 0.0385A
60
VASQSUM (0x3D), VBSQSUM (0x3E), VCSQSUM (0x3F)
These registers hold the sum of the squared voltage samples collected during the previous accumulation interval. The
values for VASQSUM, VBSQSUM, and VCSQSUM are provided directly by the CE and are not post-processed. The
magnitude of the accumulated samples is determined by:
LSB =VMAX 2 9.4045⋅10−13 V 2 h
VAH_A (0x06), VAH_B (0x07), VAH_C (0x08)
These registers hold the apparent energy collected during the previous accumulation interval. The magnitude of the
accumulated samples is determined by:
VMAX IMAX
LSB = 9.4045⋅10−13
VAh
In _8
Since the VAh calculation involves the post-processor, these registers will not be functional when the CE_ONLY bit in the
CONFIG register is set.
VARH_A (0x03), VARH_B (0x04), VARH_C (0x05)
These registers hold the reactive energy collected during the previous accumulation interval. The magnitude of the
accumulated samples is determined by:
VMAX IMAX
LSB = 9.4045⋅10−13
VARh
In_8
VPHASE_ABC (0x10)
This register holds the phase angle between the voltages of phases A/C and A/B. The LSB is one degree.
Bits 15-0: These bits (VPHASE_AC) hold the phase angle between VA and VC.
Bits 31-16: These bits (VPHASE_AB) hold the phase angle between VA and VB.
VRMS_A (0x09), VRMS_B (0x0A), VRMS_C (0x0B)
These registers hold the post-processed RMS voltage for each phase. Only the 16 most significant bits are used. The
magnitude of the values is determined by:
6.8781⋅10−9VMAX
LSB =
V rms
SUM _CYCLES
Since the RMS calculation involves the post-processor, these registers will not be functional when the CE_ONLY bit in the
CONFIG register is set.
If higher precision is required, the host must calculate the RMS voltages from the values in the VASQSUM, VBSQSUM, and
VCSQSUM registers.
Example: The register VRMS_B reads the value 425,778,000. Assuming VMAX to be 600V, and using the
formula above, we determine the RMS voltage of phase B to:
6.8781⋅10−9 600
VRMS = 425778000 ⋅
= 226.85V
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© 2005-2008 TERIDIAN Semiconductor Corporation
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