SA2002P Datasheet, PDF (5/14 Pages) Sames – Programmable Single Phase Kilowatt-hour Energy IC for Mechanical Counter Application

SA2002P
sames
INPUT SIGNALS
VREF
A bias resistor of 24kW set optimum bias conditions on chip.
Calibration of the SA2002P should be done as described in the
Device Configuration section.
Current sense input (IIP and IIN)
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 16µARMS.
The values for resistors R6 and R7 can be calculated as
follows:
R6 = R7 = (IL/16µA) x RSH/2
Where:
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
16mVRMS at rated currents.
Voltage Sense Input (IVP)
The current into the A/D converter should be set at 14µARMS 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 14VRMS. The current into the A/D converter
input is set at 14µARMS via resistor R12.
Serial Data (SDA)
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.
Serial Clock (SCL)
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.
Reload (RLOAD)
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.
Test Input (TEST)
The TEST input is the manufacturers test pin and must be
connected to VSS for normal operation.
OUTPUT SIGNALS
Motor Output (MOP, MON)
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.
MOP
VDD
VSS
MON
VDD
VSS
DR-01559
t_m
t_m
t_m
Figure 4: Motor drive on MON and MOP pins
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.
LED
VDD
VSS
DR-01332
t_LED
Figure 5: LED pulse output
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