ADE7757ARN Analog Devices Inc, ADE7757ARN Datasheet - Page 14

• Manufacturer Part Number: ADE7757ARN
• Description: IC ENERGY METERING 16-SOIC
• Manufacturer: Analog Devices Inc

Specifications of ADE7757ARN

• Rohs Status: RoHS non-compliant
• Input Impedance: 320 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.8V
• Current - Supply: 5mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Meter Type: Single Phase

ADE7757
S1
0
0
1
1
*Values are generated using the nominal frequency of 450 kHz.
When selecting a suitable F
the frequency output at I
stant of 100 imp/kWh should be compared with column four of
Table V. The closest frequency in Table V will determine the
best choice of frequency (F
maximum current of 25 A is being designed, the output fre-
quency on F1 and F2 with a meter constant of 100 imp/kWh is
0.153 Hz at 25 A and 220 V (from Table IV). Looking at Table V,
the closest frequency to 0.153 Hz in column four is 0.176 Hz.
Therefore, F3 (3.44 Hz—see Table I) is selected for this design.
Frequency Outputs
Figure 1 shows a timing diagram for the various frequency out-
puts. The outputs F1 and F2 are the low frequency outputs that
can be used to directly drive a stepper motor or electromechanical
impulse counter. The F1 and F2 outputs provide two alter-
nating low frequency pulses. The F1 and F2 pulse widths (t
are set such that if they fall below 1062 ms (0.942 Hz) they are
set to half of their period. The maximum output frequencies for
F1 and F2 are shown in Table II.
The high frequency CF output is intended to be used for com-
munications and calibration purposes. CF produces a 173 ms wide
active high pulse (t
The CF output frequencies are given in Table III. As in the case
of F1 and F2, if the period of CF (t
Table V. F1 and F2 Frequency with Half-Scale AC Inputs
S0 F
0
1
0
1
0.86
1.72
3.44
6.86
1–4
(Hz)* CH1 and CH2 Half-Scale AC Input*
4
) at a frequency proportional to active power.
Frequency on F1 and F2–
0.051
0.051
0.051
0.051
MAX
1–4
(maximum load) with a meter con-
1–4
). For example, if a meter with a
F
F
F
F
frequency for a meter design,
1
2
3
4
5
) falls below 346 ms, the
0.044 Hz
0.088 Hz
0.176 Hz
0.352 Hz
1
)
–14–
CF pulse width is set to half the period. For example, if the CF
frequency is 20 Hz, the CF pulse width is 25 ms.
NOTE: When the high frequency mode is selected (i.e., SCF =
0, S1 = S0 = 1), the CF pulse width is fixed at 35 s. Therefore,
t
NO LOAD THRESHOLD
The ADE7757 also includes a no-load threshold and start-up
current feature that will eliminate any creep effects in the meter.
The ADE7757 is designed to issue a minimum output frequency.
Any load generating a frequency lower than this minimum fre-
quency will not cause a pulse to be issued on F1, F2, or CF.
The minimum output frequency is given as 0.0014% for each of
the F
energy meter with a meter constant of 100 imp/kWh on F1, F2
using F
would be 0.0014% of 3.44 Hz or 4.81 10
3.08 10
In this example, the no-load threshold would be equivalent to
1.7 W of load or a start-up current of 8 mA at 220 V. Compare
this value to the IEC 1036 specification which states that the
meter must start up with a load equal to or less than 0.4% Ib.
For a 5 A (Ib) meter, 0.4% of Ib is equivalent to 20 mA.
Negative Power Information
The ADE7757 detects when the current and voltage channels
have a phase shift greater than 90 . This mechanism can detect
wrong connection of the meter or generation of negative power.
The REVP pin output will go active high when negative power
is detected and active low if positive power is detected. The
REVP pin output changes state as a pulse is issued on CF. The
REVP pin is not functional in the current version and will only
work in the A version (ADE7757A).
4
will always be 35 s, regardless of output frequency on CF.
1–4
3
frequency selections (see Table I). For example, for an
(3.44 Hz), the minimum output frequency at F1 or F2
–3
Hz at CF (64 F1 Hz) when SCF = S0 = 1, S1 = 0.
–5
Hz. This would be
REV. A