SA2002P
Mains Zero Crossing Indication (FMO)
Figure 6 indicates the behavior of the FMO output relative to the
voltage sense inputs. 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. The FMO output may
be used during calibration.
sames
Figure 7 shows the behavior of DIR, when energy reversal
takes place. The time period for the DIR 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 DIR.
I
V
t
t
V
t
FMO
t
t MAINS
DR-01284
DIR
DR-01283
t DIR
t
Figure 6: Mains zero crossing on FMO
Figure 7: Measured energy direction on DIR
Direction Indication (DIRO)
The SA2002P provides information about the energy flow
direction on pin DIRO .
A logic 0 on pin DIRO indicates reverse energy flow. Reverse
energy flow is defined as the condition where the voltage
sense input and current sense input are out of phase (greater
than 90 degrees).
Positive energy flow, when voltage sense and both current
sense input are in phase, is indicated on pin DIRO as a logic 1.
The DIRO pin may be used to drive a LED in order to indicate
reverse energy.
Signal
Output
DIRO
Value
0
1
Description
Reverse energy flow
Forward energy flow
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