CS5463
Output pin E3 is high when the line voltage is positive
and pin E3 is low when the line voltage is negative.
5.6 Sag and Fault Detect Feature
Status bit VSAG and IFAULT in the Status Register, in-
dicates a sag occurred in the power line voltage and
current, respectively. For a sag condition to be identi-
fied, the absolute value of the instantaneous voltage or
current must be less than the sag level for more then
half of the sag duration (see Figure 9).
5.5.5 PFMON Output Mode
Setting bit E3MODE1:0 = 1 in the Operational Mode
Register outputs the PFMON comparator on pin E3.
Figure 8 illustrates the output format with PFMON on E3
E1
E2
E3
To activate Voltage Sag detect, a voltage sag level must
be specified in the Voltage Sag Level Register (VSA-
GLevel), and a voltage sag duration must be specified in
the Voltage Sag Duration Register (VSAGDuration). To
activate Current Fault detect, a current sag level must
be specified in the Current Fault Level Register (ISA-
GLevel), and a current sag duration must be specified in
the Current Fault Duration Register (ISAGDuration). The
voltage and current sag levels are specified as the aver-
age of the absolute instantaneous voltage and current,
respectively. Voltage and current sag duration is speci-
fied in terms of ADC cycles.
Above PFMON Threshold
Below PFMON Threshold
Figure 8. PFMON output to pin E3
When PFMON is greater then the threshold, pin E3 is
high and when PFMON is less then the threshold pin E3
is low.
5.5.6 Design Example
EXAMPLE #1:
The maximum rated levels for a power line meter are
250 V rms and 20 A rms. The required number of puls-
es-per-second on E1 is 100 pulses per second
(100 Hz), when the levels on the power line are
220 V rms and 15 A rms.
With a 10x gain on the voltage and current channel the
maximum input signal is 250 mV . (See Section 5.1 An-
P
alog Inputs on page 16.) To prevent over-driving the
channel inputs, the maximum rated rms input levels will
Level
register 0.6 in V
and I
by design. Therefore the
RMS
RMS
voltage level at the channel inputs will be 150 mV rms
when the maximum rated levels on the power lines are
250 V rms and 20 A rms.
Duration
Solving for PulseRate using the transfer function:
Figure 9. Sag and Fault Detect
2
FREQ × VREFIN
P
--------------------------------------------------------------------------------------------
PulseRate =
VIN × VGAIN × IIN × IGAIN × PF
5.7 On-chip Temperature Sensor
Therefore with PF = 1 and:
The on-chip temperature sensor is designed to assist in
characterizing the measurement element over a desired
temperature range. Once a temperature characteriza-
tion is performed, the temperature sensor can then be
utilized to assist in compensating for temperature drift.
VIN = 220V × ((150mV) ⁄ (250V)) = 132mV
IIN = 15A × ((150mV) ⁄ (20A)) = 112.5mV
the pulse rate is:
2
Temperature measurements are performed during con-
tinuous conversions and stored in the Temperature
Register. The Temperature Register (T) default is Cel-
100 × 2.5
-----------------------------------------------------------------
PulseRate =
= 420.8754Hz
0.132 × 10 × 0.1125 × 10
sius scale (oC). The Temperature Gain Register (T
)
and the PulseRateE Register is set to:
gain
and Temperature Offset Register (T ) are constant val-
ues allowing for temperature scale conversions.
off
PulseRate
---------------------------------------
PulseRateE =
= 0.2104377
(MCLK ⁄ K) ⁄ 2048
with MCLK = 4.096 MHz and K = 1.
DS678PP1
19