SA9604A
1. Power calulation
In the Application Circuit (Figure 1), the voltages from Line 1, Line 2 and Line 3, are
converted to currents and applied to the voltage sense inputs IVN1, IVN2 and IVN3.
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 14VRMS. The resulting
input currents into the A/D converters are 14µARMS through the resistors R15, R16 and
R17.
Forthecurrentsenseinputs,thevoltagesacrossthecurrenttransformersterminating
resistors are converted to currents of 16µARMS for rated conditions, by means of
resistors R8, R9 (Phase 1); R10, R11 (Phase 2); and R12, R13 (Phase 3).
The signals providing the current information are applied to the current sensor
inputs: IIN1; IIP1; IIN2; IIP2; IIN3; and IIP3.
2. Analog Input Configuration
The input circuitry of the current and voltage sensor inputs are illustrated below.
These inputs are protected against electrostatic discharge through clamping
diodes.
The feedback loops from the outputs of the amplifiers AI and AV generate virtual
shorts on the signal inputs. Exact copies of the input currents are generated for the
following analog signal processing circuitry.
V
DD
II P
V
V
SS
DD
CURRENT
SENSOR
INPUT S
A
I
II N
V
SS
V
DD
IV P
VOLT AGE
SENSOR
INPUT
V
SS
A
V
GND
DR-0 1 3 0 8
3. Electrostatic Discharge (ESD), Protection
The SA9604A Integrated Circuits inputs/outputs are protected against ESD.
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SAMES [ SAMES ]
