SA9108F
PIN DESCRIPTION (Continued)
Pin
Pin
Designation
PLCC-44 DIP-40
12
NC
24
NC
34
NC
44
NC
Description
Not connected
FUNCTIONAL DESCRIPTION
The SAMES SA9108F is a CMOS mixed signal Analog/Digital integrated circuit, which
performs two phase power/energy calculations over a dynamic range of greater than
1000:1, to an overall accuracy of better than Class 1.
The integrated circuit includes all the required functions for 2-phase power and energy
measurement such as oversampling A/D converters for the voltage and current sense
inputs, power calculation and energy integration. Internal offsets are eliminated through
the use of cancellation procedures.
The SA9108F generates pulses, the frequency of which is proportional to the power
consumption. The pulse rate follows the instantenous power measured. Direction
information is also provided.
1.
Power Calculation
In the Application Circuit (Figure 1), the mains voltages from Line 1 and Line 2, are
converted to currents and applied to the voltage sense inputs IVP1 and IVP2. The
mains voltage (2 x 115 V) is divided down through voltage dividers to 14V. The
resulting input currents into the A/D converters are 14µA
RMS
through the resistors R
9
and R
10
.
For the current sense inputs the voltage drop across the current transformers'
terminating resistors are converted to currents of 16µA
RMS
for rated conditions, by
means of resistors R
5
, R
6,
(Phase 1) and R
7
, R
8
(Phase 2).
The signals providing the current information are applied to the current sensor inputs
IIN1, IIP1 and IIN2, IIP2.
In this configuration, with the mains voltage of 2 x 115 VAC and rated currents of
80A, the output frequency of the SA9108F energy metering integrated circuit at
FOUT1 is 64Hz. In this case 1 pulse will correspond to an energy consumption of
2 x 9.2 kW/64Hz = 287.5 Ws.
sames
5/12
SAMES [ SAMES ]
