PM9103AP

sames

5/10

Reset Integrator:

The integrator is reset without transmitting the integrator

status.

Read/Reset Integrator: The device 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 on-chip

integrator using the "Read" command.

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

command from the controller causes the integrated circuit to complete the existing

measurement cycle, transmit the 16 most significant bits of the 22 bit integrator

via the Serial Output, to the controller and restart the integrator.

The most significant bit of the 16 bits, indicates the direction of energy consumption

measured (0 = Positive, 1 = Negative).

Refer to the SA9103C, SA9103E or SA9603C datasheets for the serial interface

command protocols.

6.

Circuit Description

The Application Circuit (figure 2) shows the components required for the serial

interface power metering module, using a shunt resistor for current sensing.

In this application the device requires +2.5V, 0V, -2.5V DC supply.

The most important external components are:

C

converters. The value of these capacitors is 560pF. The actual values determine

signal to noise and stability performance. The tolerance should be within ±10%.

C

is 3.3nF. The actual values are uncritical. Values smaller than 0.5nF and larger

than 5nF should be avoided.

R

input. The values should be selected for an input current of 16µA

/ SA9603C at maximum line current.

Values for RSH of less than 200µ

Ω should be avoided.

R

Where

I

L

= Line current

RSH

= Shunt resistor/terminating resistor

R

The values should be

selected so that the input current into the voltage sense input (virtual ground) is set

to 14µA

R

With R

conditions are set.