ADE7758 Analog Devices, ADE7758 Datasheet - Page 53

• Manufacturer Part Number: ADE7758
• Description: Poly Phase Multifunction Energy Metering IC with Per Phase Information
• Manufacturer: Analog Devices

Step 1: Set configuration registers for zero crossings on all
phases by writing the value 0x38 to the LCYCMODE register
(0x17). This sets all of the ZXSEL bits to Logic 1.
Step 2: Set the interrupt mask register for zero-crossing
detection on all phases by writing 0xE00 to the MASK[0:24]
register (0x18). This sets all of the ZX bits to Logic 1.
Step 3: Set up the calibration system for one of the three test
conditions: I
Step 4: Read the rms registers after the zero-crossing interrupt
and take an average of N samples. This is recommended to get
the most stable rms readings. This procedure is detailed in
Figure 84—Steps 4a through 4e.
Step 4a. Choose the number of samples, N, to be averaged.
Step 4b. Reset the interrupt status register by reading RSTATUS
(0x1A).
Step 4c. Wait for the zero-crossing interrupt. When the zero-
crossing interrupt occurs, move to Step 4d.
STEP 5
WRITE TO
XVRMSOS
XIRMSOS
TEST
YES
and V
STEP 1
STEP 2
CONFIGURATION
ZERO CROSSING
ZERO CROSSING
REGISTERS FOR
ON ALL PHASES
SET INTERRUPT
ON ALL PHASES
NOM
MASK FOR
PHASES?
TESTED
START
, I
ALL
SET
MAX
SYSTEM FOR
I
TEST
/500 and V
SET UP
, V
NOM
NO
2
STEP 4
SET UP SYSTEM
CONDITIONS?
NOM
REGISTERS
READ RMS
FOR I
TESTED
V
NOM
, I
ALL
TEST
TEST
3
/20
STEP 3
,
and V
I
MAX
SYSTEM FOR
Figure 84. RMS Calibration Routine
1
SET UP
/500, V
NOM
/20.
Rev. A | Page 53 of 68
NOM
STEP 4D
Step 4d. Read the xIRMS (0x0A) and xVRMS (0x0C) registers.
These values will be averaged in Step 4e.
Step 4e: Average the N samples of xIRMS and xVRMS. The
averaged values will be used in Step 5.
Step 5: Write to the xVRMSOS (0x36 to 0x38) and xIRMSOS
(0x33 to 0x35) registers according to the following equations.
where I
the offset correction for the input I
where V
without the offset correction for the input V
respectively.
XVRMS
XIRMS
READ
VRMSOS
IRMSOS
−
16
TEST-RMS
NOM-RMS
YES
,
STEP 4B
RESET INTERRUPT
STATUS REGISTER
1
384
INTERRUPT?
×
=
and I
=
n = n + 1
and V
(
I
64
1
TEST
×
MAX/X-RMS
STEP 4C
STEP 4A
NO
V
NOM/20-RMS
2
NOM
CHOOSE N
×
I
n = 0
NO
MAX/X
n = N?
×
are the rms register values without
V
NOM/20
are the rms register values
I
−
MAX/X
RMS
YES
TEST
V
2
NOM/20
STEP 4E
−
) (
and I
CALCULATE THE
2
RMS
AVERAGE OF N
–
–
SAMPLES
I
I
MAX/X
TEST
–
MAX/X
NOM
–
V
END
V
NOM/20
2
NOM
and V
, respectively.
2
ADE7758
×
I
TEST
×
NOM/20-RMS
V
(56)
NOM
(57)
−
RMS
−
2
RMS
,
)