SA2102D
sames
OUTPUT SIGNALS
Motor pulse output (MOP, MON)
The MOP and MON pins are complimentary outputs with a
frequency proportional to the average power consumption
measured. These outputs can be used to either directly drive a
stepper motor counter or an electro mechanical impulse
counter. The Rated Conditions Select pins (R0, R1, R2) allows
the selection of different output frequencies corresponding to
different Meter Constants. Figure 7 indicates the timing of
these signals.
In FAST mode the LED pulse output is set at a high frequency
of 1160Hz at IMAX and VNOM. This mode is useful for fast
calibration and can be used to interface to a micro-controller.
Figure 9 indicates the LED output signal in FAST mode.
POWER
Instantaneous Power
t4
t1
0V
Time
VDD
Current
MOP
Voltage
VSS
Pulse stability
disabled
t2
VDD
MON
67 - 70 µS
67 - 70 µS
VSS
t3
Pulse stability
enabled
t1 = t2 = t3 = 213ms
t4 is proportional to the average power and can be calculated
using Equation 2 and the Motor Output Constants in Table 2.
Figure 7: Motor output MON and MOP
Figure 9: LED pulse output in fast mode
LED Output (LED)
To convert pulses per kilowatt-hour to frequency (in Hz ) or vice
versa the following equations can be used:
The LED output pin provides a pulse output with a frequency
proportional to the average energy when in STANDARD mode
and the instantaneous energy when in FAST mode. This
output is primarily used for calibration purposes. The Rated
Conditions Select pins (R0, R1, R2) allow different frequencies
to be selected. The LED output is active low. Figure 8 shows
the LED waveform when in STANDARD mode.
3600
I x V
( )
1000
Frequency (pulses per second) = P/kWh
3600
I x V
P/kWh = frequency x
( )
1000
t2
t1
Vdd
Vss
where:
P/kWh = LED or MON/MOP pulse constant
I = current in amperes
t1 = 90ms
V = voltage (normally VNOM
)
t2 is proportional to the average power and can be calculated
using Equation 1 along with the appropriate LED Output
Constant in Table 1.
Direction Indicator Output (DIRO)
The direction energy flow may be ascertained by monitoring
the DIRO pin. A logic 0 on this pin indicates negative energy
flow. Positive energy flow, is indicated on pin DIRO as a logic 1.
The DIRO pin may be used to drive a LED.
Figure 8: LED pulse output in STANDARD mode
10/16
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