ADE7518ASTZF16-RL Analog Devices Inc, ADE7518ASTZF16-RL Datasheet - Page 51

• Manufacturer Part Number: ADE7518ASTZF16-RL
• Description: 1-Phase Energy Meter IC
• Manufacturer: Analog Devices Inc

Specifications of ADE7518ASTZF16-RL

• Applications: Energy Measurement
• Core Processor: 8052
• Program Memory Type: FLASH (16 kB)
• Controller Series: ADE75xx
• Ram Size: 512 x 8
• Interface: I²C, SPI, UART
• Number Of I /o: 20
• Voltage - Supply: 3.135 V ~ 3.465 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 53 shows this energy accumulation for full-scale signals
(sinusoidal) on the analog inputs. The three displayed curves
illustrate the minimum period of time it takes the energy register
to roll over when the active power gain register contents are
0x7FF, 0x000, and 0x800. The watt gain register is used to carry
out power calibration in the ADE7518. As shown, the fastest
integration time occurs when the watt gain register is set to
maximum full scale, that is, 0x7FF.
0x7F,FFFF
0x3F,FFFF
Note that the energy register contents roll over to full-scale
negative (0x800000) and continue to increase in value when the
power or energy flow is positive (see Figure 53). Conversely, if
the power is negative, the energy register underflows to full-
scale positive (0x7FFFFF) and continues to decrease in value.
By using the interrupt enable register, the ADE7518 can be
configured to issue an ADE interrupt to the 8052 core when the
active energy register is half full (positive or negative) or when
an overflow or underflow occurs.
Integration Time Under Steady Load: Active Energy
As mentioned previously, the discrete time sample period (T)
for the accumulation register is 1.22 μs (5/MCLK). With full-
scale sinusoidal signals on the analog inputs and the WGAIN
register set to 0x000, the average word value from each LPF2
is 0xCCCCD (see Figure 49). The maximum positive value
that can be stored in the internal 49-bit register is 2
0xFFFF,FFFF,FFFF) before it overflows. The integration time
under these conditions when WDIV = 0 is calculated in the
following equation:
0x00,0000
0x40,0000
0x80,0000
WATTHR[23:0]
Time =
0
xFFFF
Figure 53. Energy Register Rollover Time for Full-Scale Power
0
xCCCCD
3.41
,
FFFF,
(Minimum and Maximum Power Gain)
6.82
FFFF
10.2
×
. 1
22
μs
13.7
=
409
6 .
sec
TIME (Minutes)
=
. 6
WGAIN = 0x7FF
WGAIN = 0x000
WGAIN = 0x800
82
48
(or
min
Rev. 0 | Page 51 of 128
(14)
When WDIV is set to a value other than 0, the integration time
varies, as shown in Equation 15.
Active Energy Accumulation Modes
Watt-Signed Accumulation Mode
The ADE7518 active energy default accumulation mode is a
watt-signed accumulation based on the active power information.
Watt Positive-Only Accumulation Mode
The ADE7518 is placed in watt positive-only accumulation mode
by setting the POAM bit in the ACCMODE register (0x0F). In
this mode, the energy accumulation is only done for positive
power, ignoring any occurrence of negative power above or
below the no load threshold (see Figure 54). The CF pulse also
reflects this accumulation method when in this mode. The
default setting for this mode is off. Detection of the transitions
in the direction of power flow and detection of no load threshold
are active in this mode.
Watt-Absolute Accumulation Mode
The ADE7518 is placed in watt-absolute accumulation mode by
setting the ABSAM bit in the ACCMODE register (0x0F). In this
mode, the energy accumulation is done using the absolute
active power, ignoring any occurrence of power below the no
load threshold (see Figure 55). The CF pulse also reflects this
accumulation method when in this mode. The default setting
for this mode is off. Detection of the transitions in the direction
of power flow and detection of a no load threshold are active in
this mode.
Figure 54. Energy Accumulation in Positive-Only Accumulation Mode
ACTIVE ENERGY
Time = Time
ACTIVE POWER
APSIGN FLAG
THRESHOLD
THRESHOLD
NO LOAD
NO LOAD
WDIV = 0
INTERRUPT STATUS REGISTERS
× WDIV
POS
NEG
POS
ADE7518
(15)