PM9109BF
FUNCTIONAL DESCRIPTION
1. Energy Calculation
This Application Note should be read in conjunction with the SA9109B Data Sheet.
In the Application Circuit (see Figure 2), the output current from the current sensor
will be between 0 and 16µA (0 to 80A through a shunt resistor of 625µΩ). The
current input stage of the module saturates at input currents greater than
18µARMS. The mains voltage + 15% - 20%) is used to supply the circuitry with
power and to perform the energy calculation, together with the current information
from the current sensor (shunt resistor).
The SA9109BF integrated circuit may be adjusted to accommodate any voltage or
current values. The method for calculating external component values is described
in paragraph 9 (Circuit Description).
The accumulated energy is directly displayed on a 7 digit LCD. This unique
application offers a host of additional features, which are dealt with below.
2.
Electrostatic Discharge (ESD) Protection
The device's inputs/outputs are protected against ESD according to the Mil-Std
883C, method 3015. The modules resistance to transients will be dependant upon
the protection components used.
Power Consumption
The overall power consumption rating for this power metering application (Figure
2), is under 600mW, excluding the current sensor, when the supply is taken directly
from the mains.
Isolation
The programming interface and pulse output are isolated from the module which
is at mains potential, via opto-couplers. (In the event of the use of a current
transformer for current sensing, the opto-couplers would not be required).
Isolated Programming Interface
This isolated interface is provided to allow the user to programme the tariff register
values, calibration constants and manufacturer/meter identification codes. This
port is enabled by inserting the jumpers J8, J9 and J10. The programming may be
performed via the parallel port of a personal computer.
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