SA9103E
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 R1 and R2.
The current sense input saturates at an input current of ±25µA peak.
For the voltage sense input, the mains voltage (230VAC) is divided down through
a divider to 14V. The resulting current into the A/D converter input is set at 14µA
at nominal mains voltage,via resistor R4 (1MΩ).
Inthisconfiguration,withamainsvoltageof230Vandacurrentof80A,theSA9103E
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 AI and AV generate virtual
shorts on the signal inputs. Exact duplications of the input currents are generated
for the analog signal processing circuitry.
V
DD
IIP
V
V
SS
CURRENT
SENSOR
INPUTS
A
I
DD
IIN
V
V
SS
DD
IVP
VOLTAGE
SENSOR
INPUT
V
SS
A
V
DR-00919
GND
5/14
sames
SAMES [ SAMES ]
