ADE7761ARS-REF Analog Devices Inc, ADE7761ARS-REF Datasheet - Page 22

• Manufacturer Part Number: ADE7761ARS-REF
• Description: IC ENERGY METERING 20-SSOP
• Manufacturer: Analog Devices Inc

Specifications of ADE7761ARS-REF

• Rohs Status: RoHS non-compliant

ADE7761
The ADE7761 leaves the missing neutral mode for normal
operation when both conditions are no longer valid—voltage
peak value greater than 9% of full scale and zero crossing on the
voltage channel detected (see Figure 32).
Missing Neutral Gain Calibration
When the ADE7761 is in missing neutral mode, the energy is
billed based on the active current input signal level. The
calibration of the frequency outputs in this mode can be done
with the MISCAL analog input pin. In this mode, applying a dc
voltage of 330 mV on MISCAL is equivalent to applying, in
normal mode, a pure sine wave on the voltage input with a peak
value of 330 mV. The MISCAL input can vary from 0 V to
660 mV (see the Analog Inputs section). When set to 0 V, the
frequency outputs are close to zero. When set to 660 mV dc, the
frequency outputs are twice that when MISCAL is at 330 mV
dc. In other words, Equation 7 can be used in missing neutral
mode by replacing V2
AGND
Figure 32. Return to Normal Mode after Missing Neutral Detection
V2
F
1
,
F
V
V
2
2P
2N
Frequency
|V2|
+9% OF FS
ZERO-CROSSING ON V2
–9% OF FS
PEAK
rms
=
> 9% OF FULL SCALE
by MISCAL
. 5
V
FS
2P
70
AND
–V
ADC
2N
×
MISCAL
rms
V
THRESHOLD
FILTER AND
√ 2 :
REF
rms
2
/
2
MISSING
NEUTRAL
×
F
1
−
4
Rev. A | Page 22 of 28
(8)
where:
F
V1
MISCAL
pin (V).
V
F
logic inputs S0 and S1 (see Table 5).
Example
In normal mode, ac voltages of ±330 mV peak are applied to V1
and V2, and then the expected output frequency on F1 and F2 is
calculated as follows:
In missing neutral mode, ac voltage of ±330 mV peak is applied
to V1, no signal is connected on V2, and 330 mV dc input is
applied to MISCAL. With the ADE7761 in the same configura-
tion as the previous example, the expected output frequencies
on CF, F1, and F2 are
1
1-4
REF
, F
rms
is one of four possible frequencies selected by using the
is the reference voltage (2.5 V ± 8%) (V).
F
V1 = rms of 330 mV peak ac = 0.33/√ 2 V
V2 = rms of 330 mV peak ac = 0.33/√ 2 V
V
2
F
CF
F
CF
is the differential rms voltage signal on Channel 1 (V).
Frequency is the output frequency on F1 and F2 (Hz).
1–4
REF
1
1
,
,
F
F
Frequency
Frequency
rms
= 1.7 Hz, SCF = S1 = S0 = 0
= 2.5 V (nominal reference value)
2
2
Frequency
Frequency
is the differential rms voltage signal on the MISCAL
=
=
F
F
=
=
1
1
,
. 5
−
. 5
F
70
70
2
F
2
frequency
×
×
frequency
. 0
. 0
2
33
33
×
×
×
2
2
. 0
. 0
×
×
33
33
×
2
2
×
5 .
×
5 .
64
/
1
64
2
2
7 .
=
2
=
Hz
×
5
4 .
5
1
4 .
7 .
Hz
=
Hz
Hz
. 0
084
=
. 0
Hz
084
Hz