SA9603C

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3.

Electrostatic Discharge (ESD) Protection

The SA9603C integrated circuit's inputs/outputs are protected against ESD .

4.

Power Consumption

The power consumption rating of the SA9603C integrated circuit is less than

25mW.

5.

Serial Interface

Reading and resetting of the SA9603C's on-chip integrators, is performed via the

serial interface.

The settings are:

19 200 Baud

1 Start bit (S)

1 Stop bit (E)

No parity bits

The serial interface, having a RS232 protocol, has been designed to operate directly

with a PC (Personal Computer).

The serial interface allows for the following operations:

Read Integrator (RD): The SA9603C integrated circuit transmits the integrator

status to the controller, after the current measurement cycle has been completed

(8 mains periods maximum).

The register containing the mains frequency information is read only.

Reset Integrator (RES): The SA9603C integrator is reset, without transmitting the

integrator status.

Read/Reset Integrator (RD/RES): The SA9603C transmits the integrator status

and resets the integrator after the current measurement cycle has been completed.

In a typical application, the system controller monitors the status of the SA9603C's

integrator using the "Read" command. At rated load conditions, the capacity of the

22 bit integrator allows for an integration time of 2 seconds, prior to integrator

overflow.

If after a "Read" command, the integrator value is sufficently high, a "Read/Reset"

command from the controller causes the SA9603C integrated circuit to complete

the existing measurement cycle, transmit the most significant bits of the 22 bit

integrator via the Serial Output (SOUT) to the controller and restart the integrator.

In order to ensure correct measurements, the integrator commands ("Read" and

"Read/Reset") are only executed after completion of the internal offset calibration

cycle. The cycle length is 8 mains periods.

Thus, for power calculations, the time value should be taken from the difference in

time from the previously received energy value to the currently received value.

By adapting the "Read/Reset" rate to the line current, the accuracy of the

measurement can be achieved down to lowest signal levels.