ADE7753ARSZ Analog Devices Inc, ADE7753ARSZ Datasheet - Page 24

• Manufacturer Part Number: ADE7753ARSZ
• Description: IC ENERGY METERING 1PHASE 20SSOP
• Manufacturer: Analog Devices Inc

Specifications of ADE7753ARSZ

• Input Impedance: 390 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.8V
• Current - Supply: 3mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-SSOP (0.200", 5.30mm Width)
• Meter Type: Single Phase
• Ic Function: Single-Phase Multifunction Metering IC
• Supply Voltage Range: 4.75V To 5.25V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: SSOP
• No. Of Pins: 20
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-ADE7753ZEB - BOARD EVALUATION AD7753
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

ADE7753
With the specified full-scale analog input signal of 0.5 V, the
ADC produces an output code that is approximately
±2,642,412d—see the Channel 1 ADC section. The equivalent
rms value of a full-scale ac signal are 1,868,467d (0x1C82B3).
The current rms measurement provided in the ADE7753 is
accurate to within 1% for signal input between full scale and full
scale/100. The conversion from the register value to amps must
be done externally in the microprocessor using an amps/LSB
constant. To minimize noise, synchronize the reading of the rms
register with the zero crossing of the voltage input and take the
average of a number of readings.
Channel 1 RMS Offset Compensation
The ADE7753 incorporates a Channel 1 rms offset compensa-
tion register (IRMSOS). This is a 12-bit signed register that can
be used to remove offset in the Channel 1 rms calculation. An
offset could exist in the rms calculation due to input noises that
are integrated in the dc component of V
calibration allows the content of the IRMS register to be
maintained at 0 when no input is present on Channel 1.
One LSB of the Channel 1 rms offset is equivalent to 32,768 LSB
of the square of the Channel 1 rms register. Assuming that the
maximum value from the Channel 1 rms calculation is
1,868,467d with full-scale ac inputs, then 1 LSB of the Channel 1
rms offset represents 0.46% of measurement error at –60 dB
down of full scale.
where IRMS
To measure the offset of the rms measurement, two data points
are needed from non-zero input values, for example, the base
current, I
measurements.
IRMS =
b
, and I
0
is the rms measurement without offset correction.
IRMS
max
/100. The offset can be calculated from these
0
+ IRMSOS
0xD7AE14
0x2851EC
CHANNEL 1
CURRENT SIGNAL (i(t))
0x00
×
32768
2
(t). The offset
HPF1
24
Figure 53. Channel 1 RMS Signal Processing
Rev. A | Page 24 of 60
(4)
LPF3
sgn
2
25
CHANNEL 2 ADC
Channel 2 Sampling
In Channel 2 waveform sampling mode (MODE[14:13] = 1,1
and WSMP = 1), the ADC output code scaling for Channel 2 is
not the same as Channel 1. The Channel 2 waveform sample is a
16-bit word and sign extended to 24 bits. For normal operation,
the differential voltage signal between V2P and V2N should not
exceed 0.5 V. With maximum voltage input (±0.5 V at PGA gain
of 1), the output from the ADC swings between 0x2852 and
0xD7AE (±10,322d). However, before being passed to the wave-
form register, the ADC output is passed through a single-pole,
low-pass filter with a cutoff frequency of 140 Hz. The plots in
Figure 54 show the magnitude and phase response of this filter.
The LPF1 has the effect of attenuating the signal. For example,
if the line frequency is 60 Hz, then the signal at the output of
LPF1 is attenuated by about 8%.
Note LPF1 does not affect the active power calculation. The
signal processing chain in Channel 2 is illustrated in Figure 55.
2
26
IRMSOS[11:0]
2
–10
–20
–30
–40
–50
–60
–70
–80
–90
27
H
+
0
10
(
1
f
2
)
17
Figure 54. Magnitude and Phase Response of LPF1
50Hz, –19.7°
=
2
16
60Hz, –23.2°
2
1
15
+
0x1C82B3
⎛
⎜ ⎜
⎝
50Hz, –0.52dB
140
24
60
1
0x00
Hz
I
RMS
Hz
FREQUENCY (Hz)
(t)
IRMS
02875-0-0051
⎞
⎟ ⎟
⎠
2
10
=
2
. 0
60Hz, –0.73dB
919
=
−
. 0
73
dB
02875-0-053
10
3
–2
–4
–6
–8
–10
–12
–14
–16
–18
0
(5)