SA9105A
PIN DESCRIPTION (Continued)
Pin
PLCC
12
24
34
44
Pin
DIP
Designation
NC
NC
NC
NC
Description
Not connected
FUNCTIONAL DESCRIPTION
The SAMES SA9105A is a CMOS mixed signal Analog/Digital integrated circuit, which
performs three phase power/energy calculations over a range of 1000:1, to an overall
accuracy of better than Class 1.
The integrated circuit includes all the required functions for 3-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 SA9105A generates pulses, the frequency of which is proportional to the power
consumption. Three frequency outputs (FOUT1, FOUT2 and FOUT3) are available.
1.
Power Calculation
In the Application Circuit (Figure 1), the mains voltages from Line 1, Line 2 and Line
3, are converted to currents and applied to the voltage sense inputs IVP1, IVP2 and
IVP3.
The current levels on the voltage sense inputs are derived from the mains voltage
(3 x 230 VAC) being divided down through voltage dividers to 14V. The resulting
input currents into the A/D converters are 14µA through the resistors R
15
, R
16
and
R
17
.
For the current sense inputs the voltage drop across the current transformers
terminating resistors are converted to currents of 16µA for rated conditions, by
means of resistors R
8
, R
9
(Phase 1); R
10
, R
11
(Phase 2) and R
12
, R
13
(Phase 3).
The signals providing the current information are applied to the current sensor inputs
IIN1, IIP1; IIN2, IIP2 and IIN3, IIP3.
In this configuration, with the mains voltage of 3 x 230 V and rated currents of 80A,
the output frequency of the SA9105A energy metering integrated circuit at FOUT1
is 1.16kHz. In this case 1 pulse will correspond to an energy consumption of 3 x 18.4
kW/1160Hz = 47.6 Ws.
The output frequency at FOUT2 is FOUT1/4. At FOUT3 the output frequency is
FOUT1/290.
sames
5/12
SAMES [ SAMES ]
