71M6515H-IGT/F Maxim Integrated Products, 71M6515H-IGT/F Datasheet - Page 36

• Manufacturer Part Number: 71M6515H-IGT/F
• Description: IC ENERGY METER AFE 3PH 64-LQFP
• Manufacturer: Maxim Integrated Products

Specifications of 71M6515H-IGT/F

• Mounting Style: SMD/SMT
• Package / Case: LQFP-64
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Registers Used for Calibration
CAL_IA (0x24), CAL_VA (0x25), CAL_IB (0x26), CAL_VB (0x27), CAL_IC (0x28), CAL_VC (0x29):
KVAR (0x2F)
PHADJ_A (0x2A), PHADJ_B (0x2B), PHAD_C (0x2C)
QUANT_W (0x36), QUANT_VAR (0x37), QUANT_I (0x38)
Page: 36 of 60
If a voltage measurement of phase C is higher than expected, CAL_VC has to be adjusted to:
Error must be expressed as a fraction, not a percentage value.
If the percent error is +3.5%, the relative error is 0.035, and the calibration factor becomes:
which is rounded up to15830.
This register holds the relative gain of the VAR calculation with respect to the Watt calculation. The value should always be
6444.
These registers hold the phase correction factors for channels A, B, and C. The values are used by the CE to compensate
for phase errors induced by current transformers. The allowed range is (2
These registers hold DC values that are added to each calculated product in order to compensate for internal quantization
(a very small amount) and external noise. These values are normally set to zero. The LSB values for these variable are
listed in Table 7.
These registers adjust the gain for the current and voltage measurements of each phase for the purpose of calibration. The
calibration factors have to be stored by the host and written to the registers of the 71M6515H after power-up. The allowed
range is (2
section for applicable values.
If the CE is operated in Rogowski Coil mode, no phase compensation should be required. The default value is not zero and
should need to be changed only slightly, if at all. See the Calibration section for details.
Nonlinearity is most noticeable at low currents, and can result from input noise and truncation. Nonlinearities can be
eliminated using the QUANT_W register. The error can be seen as the presence of a virtual constant noise current that
becomes dominant at small load currents.
The value to be used for QUANT_W can be determined by the following formula:
CAL_VC = 16384 / (1 + error)
CAL_VC = 16384 / (1 + 0.035) = 15829.952,
Where error = observed error at a given voltage (V) and current (I),
VMAX = voltage scaling factor, as described in section Scaling of Measured Values
IMAX = current scaling factor, as described in section Scaling of Measured Values
LSB = QUANT LSB value = 1.04173*10
A Maxim Integrated Products Brand
15
– 1) to –(2
Variable
QUANT_W
QUANT_VAR
QUANT_I
15
– 1). The default value of 16384 equals unity gain.
LSB Value
(VMAX IMAX/ In_8)* 1.04173*10
(VMAX IMAX / In_8)* 1.04173*10
(IMAX
© 2005−2011 Teridian Semiconductor Corporation
Table 7: LSB Values for QUANT Variables
QUANT
2
/ In_8
-9
W
2
)* 5.08656*10
_
W
=
−
VMAX
error
100
-13
⋅
V
-9
IMAX
-9
⋅
I
⋅
In
⋅
_
LSB
15
8
Unit
W
VAR
A (rms)
-1) to -(2
Energy Meter IC
15
-1). See the Calibration Procedure
DATA SHEET
71M6515H
JULY 2011
1.6