SPEC-1081 (REV. 2)

10/15

29-09-2017

SA4101A

Direction Select Input (DIRI)

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.

measured in the positive direction. Energy flowing in the

negative direction will not be measured. Connecting DIRI to

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.

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 and R2)

allow

the

selection

of

different

output

frequencies

corresponding to different meter constants. Figure 8 indicates

the timing of these signals.

using Equation 2 and the motor output constants in Table 2.

Figure 8: Motor outputs MON and MOP

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.

using Equation 1 along with the appropriate LED output

constant in Table 1.

Figure 9: LED pulse output in STANDARD mode

In FAST mode the LED pulse output is set at a high frequency

calibration and can be used to interface to a microcontroller.

Figure 10 indicates the LED output signal in FAST mode.

Figure 10: LED pulse output in fast mode

To convert pulses per kilowatt-hour to frequency (in Hz) or

vice versa the following equations can be used:

������������������������������������ = ����/��������ℎ (

1000 × 3600

���� × ����

)

⁄

����/��������ℎ = ������������������������������������ × (

1000 × 3600

���� × ����

)

where

P/kWh is the LED or MON/MOP pulse constant

I is the current in amperes

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.

t

1

t

4

t

2

MON

MOP

t

3

t

1

t

2

Time

Amplitude

Current

Voltage

Instantaneous Power

Pulse Stability

disabled

(SO to V

Pulse Stability

enabled

(SO to V

67-70µs