SA9102C

sames

5/12

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 200µ

Ω). This voltage is

converted to a current of between 0 and 16µA, by means of resistors R

The current sense input saturates at an input current of ±25µA peak.

For the voltage sensor input, the mains voltage (230VAC) is divided down through

a divider to 14V. The current into the A/D converter input is set at 14µA for a nominal

mains voltage, via the resistor R4 (1M

Ω).

In this configuration, with a mains voltage of 230V and a current of 80A, the output

frequency of the SA9102C power meter chip at FOUT1 (Pin 12) is 1.16kHz. In this

case 1 pulse will correspond to an energy consumption of 18.4kVA/1160Hz =

15.9Ws.

The output frequency at FOUT2 is FOUT1 /290 (i.e. The frequency ouput at pin 12

is divided by 290).

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, in conjunction with the amplifiers input configuration.

The feedback loops from the outputs of the amplifiers A

shorts on the signal inputs. Exact duplications of the input currents are generated

for the analog signal processing circuitry.

VOLTAGE

SENSOR

INPUT

IVP

DR-00502

SS

V

CURRENT

SENSOR

INPUTS

IIP

IIN

DD

SS

V

V

SS

V

DD

V

DD

V

GND