SA2007H
Positive energy flow, when voltage sense and both current
sense input are in phase, is indicated on pin D1 or D2 as a logic
1.
Figure 5 shows the behavior of D1 and D2, when energy
reversal takes place. The time period for the direction signal to
change state, t
DIR
, is the time it takes for the internal integrator
to count (down) from its present value to zero. Thus the energy
consumption rate determines the speed of change on the
direction outputs.
sames
Interrupt (INT)
While the SA2007H is operating in latched mode (see Output
mode description) an interrupt is generated with the falling
edge of the pulse outputs P1 and P2 (see figure 7). INT is
cleared with a logic 1 on the RP input.
OUTPUT SIGNALS IN LATCHED MODE
Latched mode is selected by setting the OMODE input to logic
1. This mode is used with a micro controller to ensure that any
simultaneous pulses on P1 and P2 are not missed. The
functionality of the latched mode is shown in figure 7.
An interrupt is generated with a falling edge on any of the pulse
output signals P1 and P2. The micro controller needs to scan
the status of the pulse outputs as well as the direction signals
D1 and D2 during its interrupt service routine. The micro
controller clears the interrupt by setting the RP input to a logic
1. The pulse outputs P1 and P2 are cleared along with the
interrupt. Note that energy pulses are inhibited when the
interrupt output is set (during latched mode).
FMO
I
t
V
t
D1, D2
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t DIR
t
P1
Figure 5: Measured energy direction on D1 or D2
Mains zero crossing indication (FMO)
The square wave signal of FMO indicates the polarity of the
mains voltage. Due to comparator offsets, the FMO low to high
transition can occur within a range as shown in figure 6. The
time between successive low to high transitions will be equal to
the mains voltage period.
P2
INT
RP
dr-01621
Figure 7: Output signals in latched mode
V
t
FMO
t
t MAINS
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Figure 6: Mains zero crossing on FMO
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PRELIMINARY
SAMES [ SAMES ]
