ADE7569ASTZF16 Analog Devices Inc, ADE7569ASTZF16 Datasheet - Page 59

• 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

I
V
PHASE COMPENSATION
The ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/
ADE7569 must work with transducers that can have inherent
phase errors. For example, a phase error of 0.1° to 0.3° is not
uncommon for a current transformer (CT). These phase errors
can vary from part to part, and they must be corrected to perform
accurate power calculations. The errors associated with phase
mismatch are particularly noticeable at low power factors. The
ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/ADE7569
provide a means of digitally calibrating these small phase errors.
The part allows a small time delay or time advance to be intro-
duced into the signal processing chain to compensate for small
phase errors. Because the compensation is in time, this technique
should be used only for small phase errors in the range of 0.1°
to 0.5°. Correcting large phase errors using a time shift technique
can introduce significant phase errors at higher harmonics.
The phase calibration register (PHCAL[7:0], Address 0x10) is a
twos complement, signed, single-byte register that has values
ranging from 0x82 (−126d) to 0x68 (+104d).
The PHCAL register is centered at 0x40, meaning that writing
0x40 to the register gives 0 delay. By changing this register, the
time delay in the voltage channel signal path can change from
−231.93 μs to +48.83 μs (MCLK = 4.096 MHz). One LSB is
equivalent to a 1.22 μs (4.096 MHz/5) time delay or advance.
A line frequency of 60 Hz gives a phase resolution of 0.026° at
the fundamental (that is, 360° × 1.22 μs × 60 Hz).
Figure 59 illustrates how the phase compensation is used to
remove a 0.1° phase lead in the current channel due to the
external transducer. To cancel the lead (0.1°) in the current
channel, a phase lead must also be introduced into the voltage
channel. The resolution of the phase adjustment allows the
introduction of a phase lead in increments of 0.026°. The phase
lead is achieved by introducing a time advance into the voltage
channel. A time advance of 4.88 μs is made by writing −4 (0x3C)
to the time delay block, thus reducing the amount of time delay
by 4.88 μs or, equivalently, a phase lead of approximately 0.1° at a
line frequency of 60 Hz (0x3C represents −4 because the register is
centered with 0 at 0x40).
I
PA
I
V
V
N
N
P
I
PGA1
PGA2
V
60Hz
ADC 2
ADC 1
0.1°
Figure 59. Phase Calibration
1
–231.93µs TO +48.83µs
1
7
DELAY BLOCK
0
1.22µs/LSB
PHCAL[7:0]
0
1
HPF
0
1
1
24
1
0
CHANNEL 2 DELAY
REDUCED BY 4.88µs
(0.1°LEAD AT 60Hz)
0x0B IN PHCAL[7:0]
ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/ADE7569
24
V
60Hz
I
LPF2
Rev. B | Page 59 of 152
RMS CALCULATION
The root mean square (rms) value of a continuous signal V(t) is
defined as
For time sampling signals, rms calculation involves squaring the
signal, taking the average, and obtaining the square root. The
ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/ADE7569
implement this method by serially squaring the inputs, averaging
them, and then taking the square root of the average. The averaging
part of this signal processing is done by implementing a low-pass
filter (LPF3 in Figure 60, Figure 62, and Figure 63). This LPF
has a −3 dB cutoff frequency of 2 Hz when MCLK = 4.096 MHz.
where V is the rms voltage.
When this signal goes through LPF3, the cos(2ωt) term is attenu-
ated and only the dc term, V
through.
The I
the WAVMODE register (Address 0x0D) and setting the WFSM
bit (Bit 5) in the Interrupt Enable 3 SFR (MIRQENH, Address
0xDB). Like the current and voltage channel waveform sampling
modes, the waveform data is available at sample rates of
25.6 kSPS, 12.8 kSPS, 6.4 kSPS, and 3.2 kSPS.
It is important to note that when the current input is larger than
40% of full scale, the I
represent the true processed rms value. The rms value processed
with this level of input is larger than the 24-bit read by the wave-
form register, making the value read truncated on the high end.
Current Channel RMS Calculation
Each ADE7116/ADE7156/ADE7166/ADE7169/ADE7566/
ADE7569 simultaneously calculates the rms values for the current
and voltage channels in different registers. Figure 61 and Figure 62
show the details of the signal processing chain for the rms
calculation on the current channel. The current channel rms
value is processed from the samples used in the current channel
waveform sampling mode and is stored in an unsigned 24-bit
register (I
equivalent to 1 LSB of a current channel waveform sample.
V
V
V
rms
rms
( )
2
t
) (
signal can be read from the waveform register by setting
V (t ) = √2 × V sin(ωt )
INPUT
t
rms
=
=
=
). One LSB of the current channel rms register is
V
2
T
1
2
×
×
−
V
T
∫
0
V
Figure 60. RMS Signal Processing
V
sin(
2
2
V
rms
cos
2
(
ω
t
(t) = V
)
waveform sample register does not
t
(
dt
)
2
ω
rms
2
t
– V
)
2
(shown as V
2
cos (2ωt)
LPF3
V
2
(t ) = V
2
2
in Figure 60) goes
V
(3)
(4)
(5)