ADE7758ARW Analog Devices Inc, ADE7758ARW Datasheet - Page 49

• Manufacturer Part Number: ADE7758ARW
• Description: IC ENERGY METERING 24-SOIC
• Manufacturer: Analog Devices Inc

Specifications of ADE7758ARW

• Rohs Status: RoHS non-compliant
• Input Impedance: 380 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.8V
• Current - Supply: 8mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (0.300", 7.50mm Width)
• Meter Type: 3 Phase
• Lead Free Status / RoHS Status: Not Compliant

Gain Calibration Using Line Accumulation
Gain calibration is used for meter-to-meter gain adjustment,
APCF or VARCF output rate calibration, and determining the
Wh/LSB, VARh/LSB, and VAh/LSB constant.
Step 0: Before performing the gain calibration, the APCFNUM/
APCFDEN (0x45/0x46) and VARCFNUM/ VARCFDEN
(0x47/0x48) values can be set to achieve the correct impulses/kWh,
impulses/kVAh, or impulses/kVARh using the same method
outlined in Step 4 in the Gain Calibration Using Pulse Output
section. The calibration of xWG/xVARG/xVAG (0x2A through
0x32) is done with the line accumulation mode. Figure 81 shows
the steps involved in calibrating the gain registers using the line
accumulation mode.
Step 1: Clear xWG, xVARG, and xVAG.
VARCFNUM/VARCFDEN
STEP 0
STEP 1
STEP 2
APCFNUM/APCFDEN
FOR LINE PERIOD
FREQ[11:0] FOR A
MEASUREMENT
MEASUREMENT
SELECT PHASE
xWG/xVAR/xVAG
LINE PERIOD
CONFIGURE
CLEAR
AND
SET
STEP 7
READ FREQ[11:0]
REGISTER
Figure 81. Gain Calibration Using Line Accumulation
NO
STEP 3
STEP 4
STEP 5
STEP 6
LENERGY INTERRUPT
SET ACCUMULATION
SET UP SYSTEM FOR
I
TEST
TIME (LINECYC)
SET MASK FOR
SET LYCMODE
FREQUENCY
REGISTER
KNOWN?
, V
Rev. D | Page 49 of 72
NOM
, PF = 1
READ ALL xWATTHR
WRITE TO xWG AND
STEP 9A
STEP 9B
STEP 10
AND xVAHR AFTER
YES
STEP 8
STEP 9
CALCULATE xVAG
CALCULATE xWG
RESET STATUS
Step 2: Select Phase A, Phase B, or Phase C for a line period
measurement with the FREQSEL[1:0] bits in the MMODE
register (0x14). For example, clearing Bit 1 and Bit 0 selects
Phase A for line period measurement.
Step 3: Set up ADE7758 for line accumulation by writing 0xBF
to LCYCMODE. This enables the line accumulation mode on
the xWATTHR, xVARHR, and xVAHR (0x01 to 0x09) registers
by setting the LWATT, LVAR, and LVA bits, LCYCMODE[0:2]
(0x17), to Logic 1. It also sets the ZXSEL bits, LCYCMODE[3:5],
to Logic 1 to enable the zero-crossing detection on all phases for
line accumulation. Additionally, the FREQSEL bit,
LCYCMODE[7], is set so that FREQ (0x10) stores the line
period. When using the line accumulation mode, the
RSTREAD bit of LCYCMODE should be set to 0 to disable the
read with reset mode. Select the phase for line period
measurement in MMODE[1:0].
Step 4: Set the number of half-line cycles for line accumulation
by writing to LINECYC (0x1C).
INTERRUPT
REGISTER
LENERGY
CALIBRATE WATT
AND VA @ PF = 1
xVAG
STEP 12
STEP 13
STEP 14
CALCULATE xVARG
STEP 15
STEP 16
STEP 11
READ ALL xVARHR
PF = 0, INDUCTIVE
Wh/LSB, VAh/LSB,
WRITE TO xVARG
AFTER LENERGY
RESET STATUS
SET UP TEST
SYSTEM FOR
CALCULATE
I
INTERRUPT
TEST
REGISTER
VARh/LSB
, V
END
NOM
,
ADE7758