Data Sheet AS8118

Revision 1.8, 15-Feb-05

Page 8 of 30

The default pulse rate of CAL is MON/MOP x 16. The default pulse rate is the pulse rate available at the output, without any

programming required to the AS8118.

(Note: As the default pulse rate of MON/MOP is 400 imp/kWh, the actual CAL default pulse rate is 400 x 16 = 6,400

imp/kWh)

As an example, the maximum selectable pulse rate of CAL is 64 * 800 = 51,200 imp/kWh (See MON/MOP below)

The CAL pulse width is fixed at 1ms and is shown in the Timing Diagram and Timing Parameters that follow.

Stepper Motor Drive Outputs (MON & MOP):

The MON and MOP outputs may be used to directly drive an electromechanical

counter or a stepper motor counter. The output frequencies are proportional to the real power measured. The required format

of the signal for driving a mechanical counter, activated by a 2-phase stepper motor is provided by the difference between

the MON and MOP outputs.

The output pulse rate is programmable via the on-chip memory, with 4 pulse rate options being available:

Parameter: F_mon_sel

Setting

MON/MOP Output Pulse Rate

00

100 imp/kWh

01

200 imp/kWh

10

400 imp/kWh

11

800 imp/kWh

The default MON/MOP pulse rate is set at 400 imp/kWh. The default pulse rate is the pulse rate available at the output,

without any programming required to the AS8118.

The widths of the MON/MOP pulses are 200ms for all settings up to 800imp/kWh. Above 800imp/kWh, the MON/MOP pulse

widths maintain a constant 50% duty cycle and is shown in the Timing Diagram and Timing Parameters that follows.

LED Driver Pulse Output (LED):

The LED output is a low frequency output, the frequency of which is proportional to the real

power measured. The pulse rate is programmable via the on-chip memory the selected pulse rate is independent of the

settings of both the selected CAL and the MON/MOP settings.

Parameter: F_led_sel

Setting

LED Output Pulse Rate

000

100 imp/kWh

001

200 imp/kWh

010

400 imp/kWh

011

800 imp/kWh

100

1600 imp/kWh

101

3200 imp/kWh

110

6400 imp/kWh

The default LED pulse rate is set at 3200 imp/kWh. The default frequency is the frequency available at the output, without

any programming required to the AS8118.

The width of the LED pulse is 80 ms for all settings except where the LED stream is shorter than 160ms. In this case, a 50%

duty cycle is maintained. The format of the LED signal is shown in the Timing Diagram and Timing Parameters below.