ADE7759ARSRL Analog Devices Inc, ADE7759ARSRL Datasheet - Page 15

• Manufacturer Part Number: ADE7759ARSRL
• Description: IC ENERGY METERING 1PHASE 20SSOP
• Manufacturer: Analog Devices Inc

Specifications of ADE7759ARSRL

• Rohs Status: RoHS non-compliant
• 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
• For Use With: EVAL-ADE7759EBZ - BOARD EVALUATION FOR ADE7759

INTERRUPTS
ADE7759 interrupts are managed through the interrupt status
register (STATUS[7:0]) and the interrupt enable register
(IRQEN[7:0]). When an interrupt event occurs in the ADE7759,
the corresponding flag in the status register is set to a Logic 1—see
Interrupt Status Register section. If the enable bit for this
interrupt in the interrupt enable register is Logic 1, then the
IRQ logic output goes active low. The flag bits in the status
register are set irrespective of the state of the enable bits.
To determine the source of the interrupt, the system master
(MCU) should perform a read from the status register with
reset (RSTATUS[7:0]). This is achieved by carrying out a
read from address 05h. The IRQ output will go logic high on
completion of the interrupt status register read command—
see Interrupt Timing section. When carrying out a read with
reset, the ADE7759 is designed to ensure that no interrupt
events are missed. If an interrupt event occurs just as the status
register is being read, the event will not be lost and the IRQ
logic output is guaranteed to go high for the duration of the
interrupt status register data transfer before going logic low
again to indicate the pending interrupt. See the following
section for a more detailed description.
Using the ADE7759 Interrupts with an MCU
Figure 17 shows a timing diagram with a suggested implementa-
tion of ADE7759 interrupt management using an MCU. At
time t
more interrupt events have occurred in the ADE7759. The IRQ
logic output should be tied to a negative edge-triggered external
interrupt on the MCU. On detection of the negative edge, the
REV. A
1
, the IRQ line will go active low, indicating that one or
SEQUENCE
PROGRAM
DOUT
SCLK
IRQ
DIN
CS
IRQ
MCU
t
1
t
1
JUMP
ISR
TO
0
READ STATUS REGISTER COMMAND
0
INTERRUPT
MASK SET
GLOBAL
0
0
CLEAR MCU
INTERRUPT
Figure 17. Interrupt Management
FLAG
0
Figure 18. Interrupt Timing
1
0
STATUS WITH
RESET (05h)
READ
t
1
2
–15–
MCU should be configured to start executing its Interrupt Ser-
vice Routine (ISR). On entering the ISR, all interrupts should
be disabled using the global interrupt enable bit. At this point,
the MCU external interrupt flag can be cleared to capture inter-
rupt events that occur during the current ISR.
When the MCU interrupt flag is cleared, a read from the status
register with reset is carried out. This will cause the IRQ line to
be reset logic high (t
status register contents are used to determine the source of
the interrupt(s), and thus the appropriate action will be taken. If
a subsequent interrupt event occurs during the ISR, that event
will be recorded by the MCU external interrupt flag being set
again (t
will be cleared (same instruction cycle) and the external inter-
rupt flag will cause the MCU to jump to its ISR once again. This
will ensure that the MCU does not miss any external interrupts.
Interrupt Timing
The Serial Interface section should be reviewed first, before the
Interrupt Timing section. As previously described, when the
IRQ output goes low, the MCU ISR must read the interrupt
status register to determine the source of the interrupt. When
reading the status register contents, the IRQ output is set high
on the last falling edge of SCLK of the first byte transfer (read
interrupt status register command). The IRQ output is held
high until the last bit of the next 8-bit transfer is shifted out
(interrupt status register contents)—see Figure 18. If an inter-
rupt is pending at this time, the IRQ output will go low again. If
no interrupt is pending, the IRQ output will stay high.
t
t
9
11
3
DB7
STATUS CONTENTS)
). On returning from the ISR, the global interrupt mask
ISR ACTION
(BASED ON
STATUS REGISTER CONTENTS
t
2
3
)—see Interrupt Timing section. The
t
11
GLOBAL INTERRUPT
MASK RESET
MCU
INTERRUPT
FLAG SET
ISR RETURN
DB0
JUMP
ISR
TO
ADE7759