SA2005P
rated current the resistor values should be selected for input
currents of 16µA
RMS
. Referring to figure 8, the resistors R1 and
R2 on current channel 1, resistors R3 and R4 on current
channel 2 and resistors R5 and R6 on current channel 3, define
the current level into the current sense inputs of the SA2005P.
The current sense inputs saturates at an input current of
±25µA peak. Resistors R29, R30 and R31 are used as current
transformer termination resistors. The voltage drop across the
termination resistors should be at least 20mV at rated
conditions. Values for the current sense inputs are calculated
as follows:
R
1
= R
2
= ( I
L
/ 16µA
RMS
) x R
29
/ 2
R
3
= R
4
= ( I
L
/ 16µA
RMS
) x R
30
/ 2
R
5
= R
6
= ( I
L
/ 16µA
RMS
) x R
31
/ 2
Where:
I
L
= Line current/CT-ratio
In case a current transformer is used for current sensing the
value of the termination resistors should be less than the
resistance of the CT's secondary winding.
sames
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 SA2005P. For
normal operation of the SA2005P the RLOAD pin may be left
floating.
Test Inputs (TEST)
The TEST input is the manufacturers test pin and must be
connected to VSS in a metering application.
OUTPUT SIGNALS
LED Output (LED)
Four options for the LED output pulse rate are available, 6400,
3200, 1600 pulses per kWh, and a pulse rate of 1252 pulses
per second at rated conditions. At 1252 pulses per second t
LED
is 71µs, for the other options t
LED
is 10ms. The LED output is
active low as shown in figure 4.
VDD
LED
VSS
DR-01332
Voltage Sense Inputs (IVN1, IVN2, IVN3)
The mains voltage are measured by means of a resistor divider
and the divided voltage are converted to a current. The current
into the voltage sense inputs (virtual ground) should be set to
14µA
RMS
at rated voltage conditions. The individual mains
voltages are divided down to 14V
RMS
per phase. The resistors
R12, R13 and R14 (figure 8) set the current for the voltage
sense inputs. The voltage sense inputs saturate at an input
current of ±25uA peak.
t
LED
Figure 4: LED pulse output
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. A MOP pulse followed by a
MON pulse represents one energy pulse. The motor drive
waveforms are shown in figure 5.
VDD
MOP
VSS
Voltage Reference Connection (VREF)
A bias resistor of 24k provides an optimum bias conditions on
chip. Calibration of the SA2005P is done by means of divider
ratios stored on an external EEPROM. This is described in the
Device Configuration section.
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 SA2005P. An external pull-up resistor in not
needed.
VDD
MON
VSS
DR-01559
t
m
t
m
t
m
Figure 5: Motor drive on MON and MOP pins of device
Serial Clock (SCL)
The SCL pin connects directly to the SCL 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 is not
needed. The SCL output uses a soft driver and may be
overdriven by the calibration equipment.
Multiplex Output (PH/ DIR)
The PH/DIR output enables either direction or voltage
information on the phase LED driver outputs (PH1, PH2 and
PH3). This multiplex output switches between logic 1 and 0 at
a frequency of approximately 280Hz. A logic 1 enables energy
direction information on the LED driver outputs and a logic 0
enables voltage information.
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SAMES [ SAMES ]
