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sames

SA2002P

http://www.sames.co.za

INPUT SIGNALS

VREF

Serial Data (SDA)

Serial Clock (SCL)

A bias resistor of 24k

set optimum bias conditions on chip.

Calibration of the SA2002P should be done as described in the

Device Configuration section.

The SDA pin connects directly to the SDA pin of an external

EEPROM. The pin is used to transfer data between the

EEPROM and the SA2002P. An external pull up resistor in not

needed.

The SCL pin connects directly to the SCL pin of an external

EEPROM. The SCL output is used to strobe data at a rate of

50kHz out of the EEPROM. An external pull up resistor in not

needed. The SCL output uses a soft driver and may be

overdriven by the calibration equipment.

W

Current sense input (IIP and IIN)

Voltage Sense Input (IVP)

Figure 9 on page 11 shows the typical connections for the

current sensor input. The resistor R6 and R7 define the current

level into the current sense inputs of the SA2002P. At

maximum rated current the resistor values should be selected

for input currents of 16µA

.

The values for resistors R6 and R7 can be calculated as

follows:

R6 = R7 = (IL/16µA) x RSH/2

IL

=

Line current or line current/CT ratio

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.

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

at

nominal mains voltage. This is to allow a variation of ±10% for

the mains voltage without saturating the voltage sense input.

The voltage sense input saturates at an input current of ±25µA

peak. Referring to Figure 9 the typical connections for the

voltage sense input is illustrated. Resistors R1, R2 and R3 set

the current for the voltage sense input. The mains voltage is

divided down to 14V

. The current into the A/D converter

input is set at 14µA

via resistor R12.

RMS

RMS

RMS

RMS

RMS

Where:

Figure 4: Motor drive on MON and MOP pins

Reload (RLOAD)

Motor Output (MOP, MON)

A falling edge on the RLOAD pin, will trigger a register update

from the external EEPROM. This feature may be used during

calibration to load updated register data in the SA2002P. For

normal operation of the SA2002P the RLOAD pin may be left

floating.

The TEST input is the manufacturers test pin and must be

connected to V for normal operation.

The motor pulse width is programmable for 71ms, 142ms and

284ms. The MON pulse will follow the MOP pulse within the

selected pulse width time. This prevents the motor armature

being in the wrong position after a power failure. Both MOP and

MON outputs are active high. One energy pulse is represented

by a MOP pulse followed by a MON pulse. The motor drive

wave forms are shown in figure 4.

Test Input (TEST)

SS

OUTPUT SIGNALS

VDD

VDD

VSS

VSS

MON

MOP

t

m

t

m

t

m

DR-01559

Figure 5: LED pulse output

LED

t

LED

DR-01332

VDD

VSS

LED Output (LED)

The LED pin provides a pulse output and is intended for

calibration purposes. Depending on register Cled the pulse

rate can be either in slow mode or fast mode. When in slow

mode the pulse rate is a low frequency and is proportional to

the average power consumption. In fast mode the pulse rate is

a programmable high frequency output proportional to the

instantaneous power consumption. This mode is useful for fast

calibration times or can be used to interface to a micro-

controller. In slow mode the pulse width (tled) is 1ms and in fast

mode tled is 71µs. The LED output is active low as shown in

figure 5.