SA4101A
Direction Select Input (DIRI)
t1
t2
Depending on the state of the DIRI pin the energy to be
measured can be in the positive direction only, in the negative
direction only, or in both directions.
Figure 9: LED pulse output in STANDARD mode
Connecting DIRI to VDD will result in energy only being
measured in the positive direction. Energy flowing in the
negative direction will not be measured. Connecting DIRI to
VSS will result in energy only being measured in the negative
direction. Energy flowing in the positive direction will not be
measured. Connecting the DIRI pin to the DIRO output pin
enables bidirectional mode where energy is measured
regardless of direction.
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 microcontroller.
Figure 10 indicates the LED output signal in FAST mode.
Amplitude
Instantaneous Power
OUTPUT SIGNALS
Motor pulse output (MOP, MON)
Time
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 and R2)
allow the selection of different output frequencies
corresponding to different meter constants. Figure 8 indicates
the timing of these signals.
Current
Voltage
Pulse Stability
disabled
(SO to VSS
)
Pulse Stability
enabled
(SO to VDD
)
67-70µs
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 10: LED pulse output in fast mode
t4
To convert pulses per kilowatt-hour to frequency (in Hz) or
vice versa the following equations can be used:
t1
MOP
1000 × 3600
t2
퐹푟푒푞푢푒푛푐푦 = 푃/푘푊ℎ⁄ꢉ
ꢊ
푉 × 퐼
t3
MON
1000 × 3600
푉 × 퐼
푃/푘푊ℎ = 퐹푟푒푞푢푒푛푐푦 × ꢉ
ꢊ
Figure 8: Motor outputs MON and MOP
where
P/kWh is the LED or MON/MOP pulse constant
I is the current in amperes
LED Output (LED)
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 (R2, R1 and R0) allow different
frequencies to be selected. The LED output is active low.
Figure 9 shows the LED waveform when in STANDARD
mode.
V is the voltage (normally VNOM
)
Direction Indicator Output (DIRO)
The direction of energy flow may be ascertained by
monitoring the DIRO pin. A low level on this pin indicates
negative energy flow. Positive energy flow is indicated on pin
DIRO as a logic high. The DIRO pin may be used to drive an
LED.
t1 = 90ms
t2 is proportional to the average power and can be calculated
using Equation 1 along with the appropriate LED output
constant in Table 1.
SPEC-1081 (REV. 2)
29-09-2017
10/15
SAMES [ SAMES ]
