SA9103C
1.
Power calculation
In the Application Circuit (Figure 1), the voltage drop across the shunt will be
between 0 and 16mV (0 to 80A through a shunt resistor of 200µΩ). This voltage is
converted to a current of between 0 and 16µA, by means of resistors R
1
and R
2
.
The current sense input saturates at an input current of ±25µA peak.
For the voltage sensor input, the mains voltage (230V AC) is divided down through
a divider to 14V. The resulting current into the A/D converter input is 14µA at
nominal voltage, via resistor R4 (1MΩ).
In this configuration, with a mains voltage of 230V and a current of 80A, the
SA9103C functions at its optimum conditions, having a margin of 3dB for overload
available.
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 A
I
and A
V
generate virtual
shorts on the signal inputs. Exact duplications of the input currents are generated
for the analog signal processing circuitry.
V DD
IIP
CURRENT
SENSOR
INPUTS
V SS
V DD
A
I
IIN
V SS
V DD
IVP
VOLTAGE
SENSOR
INPUT
V SS
A
V
DR-00831
GND
sames
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SAMES [ SAMES ]
