ADE7878ACPZ Analog Devices Inc, ADE7878ACPZ Datasheet - Page 64

• Manufacturer Part Number: ADE7878ACPZ
• Description: IC ENERGY METERING 3PH 40LFCSP
• Manufacturer: Analog Devices Inc

Specifications of ADE7878ACPZ

• Input Impedance: 400 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.4V
• Current - Supply: 22mA
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 40-WFQFN, CSP Exposed Pad
• Meter Type: 3 Phase
• Supply Voltage Range: 3V To 3.6V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: LFCSP
• No. Of Pins: 40
• Msl: MSL 1 - Unlimited
• Peak Reflow Compatible (260 C): Yes
• Supply Voltage Min: 3V
• Rohs Compliant: Yes
• Leaded Process Compatible: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADE7854/ADE7858/ADE7868/ADE7878
INTERRUPTS
The ADE7854/ADE7858/ADE7868/ADE7878 have two interrupt
pins, IRQ0 and IRQ1 . Each of the pins is managed by a 32-bit
interrupt mask register, MASK0 and MASK1, respectively. To
enable an interrupt, a bit in the MASKx register must be set to
1. To disable it, the bit must be cleared to 0. Two 32-bit status
registers, STATUS0 and STATUS1, are associated with the inter-
rupts. When an interrupt event occurs in the ADE78xx, the
corresponding flag in the interrupt status register is set to a Logic 1
(see
the interrupt mask register is Logic 1, then the
goes active low. The flag bits in the interrupt status register are set
irrespective of the state of the mask bits. To determine the source
of the interrupt, the MCU should perform a read of the corres-
ponding STATUSx register and identify which bit is set to 1. To
erase the flag in the status register, write back to the STATUSx
register with the flag set to 1. After an interrupt pin goes low, the
status register is read and the source of the interrupt is identified.
Then, the status register is written back without any change to
clear the status flag to 0. The IRQx pin remains low until the
status flag is cancelled.
By default, all interrupts are disabled. However, the RSTDONE
interrupt is an exception. This interrupt can never be masked
(disabled) and, therefore, Bit 15 (RSTDONE) in the MASK1
register does not have any functionality. The IRQ1 pin always
goes low, and Bit 15 (RSTDONE) in the STATUS1 register is set
to 1 whenever a power-up or a hardware/software reset process
ends. To cancel the status flag, the STATUS1 register has to be
written with Bit 15 (RSTDONE) set to 1.
Certain interrupts are used in conjunction with other status
registers. The following bits in the MASK1 register work in
conjunction with the status bits in the PHNOLOAD register:
•
•
•
The following bits in the MASK1 register work with the status bits
in the PHSTATUS register:
•
•
•
The following bits in the MASK1 register work with the status bits
in the IPEAK and VPEAK registers, respectively:
•
•
Table 37
Bit 0 (NLOAD)
Bit1 (FNLOAD), available in the ADE7878 only
Bit 2 (VANLOAD)
Bit 16, (SAG)
Bit 17 (OI)
Bit 18 (OV)
Bit 23 (PKI)
Bit 24 (PKV)
and
Table 38
). If the mask bit for this interrupt in
IRQx logic output
Rev. D | Page 64 of 96
The following bits in the MASK0 register work with the status bits
in the PHSIGN register:
•
•
•
When the STATUSx register is read and one of these bits is set
to 1, the status register associated with the bit is immediately
read to identify the phase that triggered the interrupt and only
at that time can the STATUSx register be written back with the bit
set to 1.
Using the Interrupts with an MCU
Figure 79 shows a timing diagram that illustrates a suggested
implementation of the ADE7854/ADE7858/ADE7868/ADE7878
interrupt management using an MCU. At Time t
goes active low indicating that one or more interrupt events
have occurred in the ADE78xx, at which point the following
steps should be taken:
1.
2.
3.
4.
5.
If a subsequent interrupt event occurs during the ISR (t
event is recorded by the MCU external interrupt flag being set
again.
On returning from the ISR, the global interrupt mask bit is
cleared (same instruction cycle) and the external interrupt flag
uses the MCU to jump to its ISR once again. This ensures that
the MCU does not miss any external interrupts.
Figure 80 shows a recommended timing diagram when the
status bits in the STATUSx registers work in conjunction with
bits in other registers. When the IRQx pin goes active low, the
STATUSx register is read, and if one of these bits is 1, a second
Bits[6:8] (REVAPx)
Bits[10:12] (REVRPx), available in the ADE7858,
ADE7868, and ADE7878 only
Bit 9, Bit 13, and Bit 18 (REVPSUMx)
Tie the IRQx pin to a negative-edge-triggered external
interrupt on the MCU.
On detection of the negative edge, configure the MCU to
start executing its interrupt service routine (ISR).
On entering the ISR, disable all interrupts using the global
interrupt mask bit. At this point, the MCU external interrupt
flag can be cleared to capture interrupt events that occur
during the current ISR.
When the MCU interrupt flag is cleared, a read from
STATUSx, the interrupt status register, is carried out. The
interrupt status register content is used to determine the
source of the interrupt(s) and, hence, the appropriate
action to be taken.
The same STATUSx content is written back into the
ADE78xx to clear the status flag(s) and reset the IRQx line
to logic high (t
2
).
1
, the IRQx pin
3
), that