ADE7569ASTZF16 Analog Devices Inc, ADE7569ASTZF16 Datasheet - Page 62

• Manufacturer Part Number: ADE7569ASTZF16
• Description: IC ENERGY METER MCU 16K 64LQFP
• Manufacturer: Analog Devices Inc

Specifications of ADE7569ASTZF16

• 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
• Ic Function: Single Phase Energy Measurement IC
• Supply Voltage Range: 3.13V To 3.46V, 2.4V To 3.7V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: LQFP
• No. Of Pins: 64
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/ADE7569
Voltage Channel RMS Calculation
Figure 63 shows details of the signal processing chain for the rms
calculation on the voltage channel. This voltage rms estimation is
done in the ADE7116/ADE7156/ADE7166/ADE7169/
ADE7566/ADE7569 using the mean absolute value calculation,
as shown in Figure 63. The voltage channel rms value is processed
from the samples used in the voltage channel waveform sampling
mode and is stored in the unsigned 24-bit V
The update rate of the voltage channel rms measurement is
MCLK/5. To minimize noise in the reading of the register, the
V
crossing of the voltage input. This configuration is done by setting
the ZXRMS bit (Bit 2) in the MODE2 register (Address 0x0C).
With the specified full-scale ac analog input signal of 0.4 V, the
output from LPF1 in Figure 63 swings between 0x28F5 and
0xD70B at 60 Hz (see the Voltage Channel ADC section). The
equivalent rms value of this full-scale ac signal is approximately
0d1,898,124 (0x1CF68C) in the V
measurement provided in the ADE7116/ADE7156/ADE7166/
ADE7169/ADE7566/ADE7569 is accurate to within ±0.5% for
signal input between full scale and full scale/20. The conversion
from the register value to volts must be done externally in the
microprocessor using a V/LSB constant.
Voltage Channel RMS Offset Compensation
The ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/
ADE7569 incorporate a voltage channel rms offset compensation
register (VRMSOS). This is a 12-bit signed register that can be
used to remove offset in the voltage channel rms calculation. An
offset can exist in the rms calculation due to input noises and dc
offset in the input samples. One LSB of the voltage channel rms
offset is equivalent to 64 LSBs of the rms register. Assuming that
the maximum value from the voltage channel rms calculation is
0d1,898,124 with full-scale ac inputs, then 1 LSB of the voltage
channel rms offset represents 3.37% of measurement error at
−60 dB down from full scale.
where V
ACTIVE POWER CALCULATION
Active power is defined as the rate of energy flow from source
to load. It is the product of the voltage and current waveforms.
The resulting waveform is called the instantaneous power signal
and is equal to the rate of energy flow at every instant of time.
rms
register can also be configured to update only with the zero
V
rms
rms0
= V
is the rms measurement without offset correction.
rms0
+ 64 × VRMSOS
rms
register. The voltage rms
rms
register.
Rev. B | Page 62 of 152
(7)
The unit of power is the watt or joules/second. Equation 8 gives an
expression for the instantaneous power signal in an ac system.
where:
v is the rms voltage.
i is the rms current.
The average power over an integral number of line cycles (n) is
given by the expression in Equation 11.
where:
T is the line cycle period.
P is referred to as the active or real power.
Note that the active power is equal to the dc component of the
instantaneous power signal p(t) in Equation 11, that is, VI. This
is the relationship used to calculate active power in the ADE7116/
ADE7156/ADE7166/ADE7169/ADE7566/ADE7569. The instan-
taneous power signal p(t) is generated by multiplying the current
and voltage signals. The dc component of the instantaneous power
signal is then extracted by LPF2 (low-pass filter) to obtain the
active power information. This process is illustrated in Figure 64.
Because LPF2 does not have an ideal brick wall frequency
response (see Figure 65), the active power signal has some
ripple due to the instantaneous power signal. This ripple is
sinusoidal and has a frequency equal to twice the line frequency.
Because of its sinusoidal nature, the ripple is removed when the
active power signal is integrated to calculate energy (see the
Active Energy Calculation section).
0xCCCCD
0x19999A
0x00000
v
t i
P
p
p
( )
( )
) (
(
VI
t
t
=
t
)
=
=
nT
=
=
1
INSTANTANEOUS
POWER SIGNAL
VI
v
2
2
∫
(
CURRENT
i(t) = √2 × i × sin(ωt)
t
0
×
−
nT
×
)
VI
I
V
×
p
Figure 64. Active Power Calculation
sin(
) (
t i
VOLTAGE
v(t) = √2 × v × sin(ωt)
cos(
t
sin(
(
dt
)
ω
2
ω
t
=
ω
)
t
VI
)
t
)
p(t) = v × i – v × i × cos(2ωt)
ACTIVE REAL POWER
SIGNAL = v × i
(10)
(11)
(8)
(9)