ADE7762ARWZ Analog Devices Inc, ADE7762ARWZ Datasheet - Page 18

• Manufacturer Part Number: ADE7762ARWZ
• Description: IC, POLYPHASE ENERGY METERING, SOIC-28
• Manufacturer: Analog Devices Inc

Specifications of ADE7762ARWZ

• Ic Function: Polyphase Energy Metering IC With Phase Drop Indication
• Supply Voltage Range: 4.75V To 5.25V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: SOIC
• No. Of Pins: 28
• Input Impedance: 140 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.8V
• Current - Supply: 8.5mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (0.300", 7.50mm Width)
• Meter Type: 3 Phase
• Brief Features: On-Chip Creep Protection, High Frequency Output
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-ADE7762EBZ - BOARD EVALUATION FOR ADE7762
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

ADE7762
PHASE MONITOR
The ADE7762 has phase monitoring functions to detect phase
dropout, phase sequence error, and reverse polarity using four
pins. Phase dropout has the highest priority, and reverse
polarity has the lowest priority. If a phase dropout occurs, phase
sequence error indication is disabled until all three phases are
above the phase dropout level (see the Phase Dropout Error
section). Because the dropout detection level is not set to zero, a
phase can have some small voltage during a phase dropout
condition. Therefore, reverse polarity is still indicated on that
phase if the proper conditions occur.
The phase monitor circuit functions by multiplexing signals onto
the four pins. The four multiplexed pins are LED_CTRL, LED_A,
LED_B, and LED_C. Two LEDs can be connected to each pin as
shown in Figure 21. When LED_CTRL is high, LED_A is low to
turn on an LED and indicate a phase drop condition on Phase A.
When LED_CTRL is low, LED_A is high to indicate a reverse
polarity (REVP) condition on Phase A. Phase sequence error is
indicated by blinking the Phase Seq/Drop LEDs.
LED_CTRL switches at a rate of 131 kHz so that both the Phase
Seq/Drop LEDs and REVP LEDs can appear to be on simultane-
ously, which allows indication of phase dropout and REVP at the
same time. For the timing diagram, see Figure 3.
SEQ/DROP
PHASE
REVP
SEQ/DROP
R
LOAD
Figure 21. Phase Monitor Circuit
PHASE
REVP
SEQ/DROP
R
LOAD
PHASE
REVP
R
LOAD
LED_CTRL
LED_A
LED_B
LED_C
Rev. 0 | Page 18 of 28
PHASE DROPOUT ERROR
The ADE7762 indicates a phase drop condition when there is a
low voltage signal or no voltage signal on a phase. The phase
dropout condition occurs when the amplitude of the phase
drops below 20% of full-scale analog input voltage or when a
zero crossing is not followed by another zero crossing on that
phase for 150 ms. When this occurs, a phase dropout signal is
generated, and the Phase Seq/Drop LED is turned on for the
missing phase. The delay between the phase drop condition
occurring at the analog inputs and indication of the condition
on the LED outputs is approximately 150 ms. During a phase
dropout condition, energy continues to accumulate on the
dropped channel, as well as the other channels, and phase
sequence error indication is disabled. The Phase Seq/Drop LED
for the dropped phase is turned off when the zero crossings
return for more than 150 ms and there is more than 20% of full-
scale input voltage on the voltage input of that phase.
PHASE SEQUENCE ERROR
The ADE7762 detects the zero crossing of each phase. A phase
sequence error occurs when the sequence A>B>C>A> … is
violated. If a phase sequence error occurs, the Phase Seq/Drop
LEDs blink at 1 Hz (see Figure 22).
Phase sequence error and REVP can be displayed simultane-
ously. The REVP LEDs continue to indicate reverse polarity if
the proper conditions exist. For example, if the phase sequence
becomes A>C>B>A… and Phase B has negative active energy
accumulated, then the REVP LED for Phase B is on solid, and
all of the Phase Seq/Drop LEDs are blinking at 1 Hz. The delay
in indicating the phase sequence error with blinking LEDs is
approximately 150 ms from the time that a phase sequence
error occurs.
PHASE REVERSE POLARITY DETECTION
When reverse power is detected on any phase, the correspond-
ing REVP LED turns on for that phase. For example, if the
power for Phase A is negative, the REVP LED connected to
LED_A turns on. The indication of REVP on the LED_A,
LED_B, or LED_C pins is nearly instantaneous. As soon as the
input to the ADCs changes and the power is calculated such
that there is a reverse power condition on any phase, the
appropriate LED is turned on.