sames

sames

SA2002E

6/10

http://www.sames.co.za

ELECTROSTATIC DISCHARGE (ESD)

PROTECTION

The SA2002E integrated circuit's inputs/outputs are protected

against ESD.

POWER CONSUMPTION

The power consumption rating of the SA2002E integrated

circuit is less than 25mW.

INPUT SIGNALS

VREF

A bias resistor of 24kW set optimum bias conditions on chip.

Calibration of the SA2002E should be done on the voltage

input as described in Typical Applications.

Current sense input (IIP and IIN)

Figure 6 shows the typical connections for the current sensor

input. The resistor R1 and R2 define the current level into the

current sense inputs of the SA2002E. At maximum rated

current the resistor values should be selected for input currents

of 16µA

.

RMS

Values for resistors R1 and R2 can be calculated as follows:

R1 = R2 = (I /16µA) x RSH/2

L

Where I = Line current

L

RSH = Shunt resistor or termination resistor if a CT is used as

the current sensor.

The value of RSH, if used as the CT's termination resistor,

should be less than the DC resistance of the CT's secondary

winding. The voltage drop across RSH should not be less than

16mV

at rated currents.

RMS

Voltage Sense Input (IVP)

The current into the A/D converter should be set at 14µA

at

RMS

nominal mains voltage. The voltage sense input saturates at

an input current of ±25µA peak. Referring to figure 6 the typical

connections for the voltage sense input is illustrated. Resistors

R3, R4 and R5 set the current for the voltage sense input. The

mains voltage is divided down to 14V

. The current into the

RMS

A/D converter input is set at 14µA

via resistor R5.

RMS

OUTPUT SIGNAL

Pulse output (FOUT)

The output on FOUT is a pulse density signal representing the

instantaneous power/energy measurement as shown in figure

8. The minimum timing characteristics are shown in the figure

9. The output frequency may be calculated using the following

formula:

2

f = 11.16 x FOUT x ( I x I ) / I

IV

R

Where:

FOUT = Typical rated output frequency (1360Hz)

I = Input current on current sense input (16µA at rated

I

conditions)

I = Input current on voltage sense input (16µA at rated

V

conditions)

I = Reference current on VREF typically 50µA

R

An integrated anti-creep function does not allow output pulses

on FOUT if no power is measured by the device.

Figure 8: FOUT instantaneous pulse output

Figure 9: FOUT pulse width

POWER

DR-01282

FOUT

V x I

P

t

t

t

t

71µs min.

71µs

DR-01151