ADE5166_08 AD [Analog Devices], ADE5166_08 Datasheet - Page 56

• Manufacturer Part Number: ADE5166_08
• Description: Single-Phase Energy Measurement IC with 8052 MCU, RTC, and LCD Driver
• Manufacturer: AD [Analog Devices]

ADE5166/ADE5169
Figure 62 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 ADE5166/ADE5169. 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 62). Conversely, if the power is
negative, the energy register underflows to full-scale positive
(0x7FFFFF) and continues to decrease in value.
Using the interrupt enable register (MIRQENM, Address 0xDA),
the ADE5166/ADE5169 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 in the Active Energy Calculation section, 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 (Address 0x1D) set to
0x000, the average word value from each LPF2 is 0xCCCCD
(see Figure 59). The maximum positive value that can be stored in
the internal 49-bit register is 2
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 62. Energy Register Rollover Time for Full-Scale Power
0
xCCCCD
3.41
FFFF,
(Minimum and Maximum Power Gain)
6.82
FFFF
10.2
×
. 1
48
22
(or 0xFFFF,FFFF,FFFF) before it
μs
=
13.7
409
6 .
sec
=
TIME (Minutes)
. 6
82
WGAIN = 0x7FF
WGAIN = 0x000
WGAIN = 0x800
min
Rev. 0 | Page 56 of 148
(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 ADE5166/ADE5169 active energy default accumulation
mode is a watt-signed accumulation based on the active power
information.
Watt Positive-Only Accumulation Mode
The ADE5166/ADE5169 are placed in watt positive-only accumu-
lation mode by setting the POAM bit (Bit 1) in the ACCMODE
register (Address 0x0F). In this mode, the energy accumulation
is done only for positive power, ignoring any occurrence of
negative power above or below the no load threshold (see
Figure 63). 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 ADE5166/ADE5169 are placed in watt-absolute accumulation
mode by setting the ABSAM bit (Bit 0) in the ACCMODE register
(Address 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 64). 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.
Figure 63. Energy Accumulation in Positive-Only Accumulation Mode
Time = Time
ACTIVE ENERGY
ACTIVE POWER
APSIGN FLAG
THRESHOLD
THRESHOLD
NO LOAD
NO LOAD
WDIV = 0
INTERRUPT STATUS REGISTERS
× WDIV
POS
NEG
POS
(15)