cs5460 Cirrus Logic, Inc., cs5460 Datasheet - Page 12

• Manufacturer Part Number: cs5460
• Description: Single Phase Bi-directional Power/energy Ic
• Manufacturer: Cirrus Logic, Inc.

2.4 Pulse-Rate Output
As an alternative to reading the energy through the
serial port, the EOUT and EDIR pins provide a
simple interface with which signed energy can be
accumulated. Each EOUT pulse represents a prede-
termined magnitude of energy. The accompanying
EDIR level represents the sign of the energy. With
MCLK = 4.096 MHz, K = 1, and both ADC inputs
at their maximum DC values, the pulses will have
a frequency equal to that in the pulse rate register.
The following example illustrates how to calculate
the pulse-rate register contents for a given meter
design. Suppose that a single two-phase power
12
-0.5
-1.5
-2.5
0.5
-1
-2
0
-0.5
-1.0
-1.5
-2.0
-2.5
0.5
0.0
0
0
Figure 7. Current Input Filter Roll-off
200
Figure 6. Voltage Input Filter Roll-off
200
400
400
600
600
800
Frequency (Hertz)
800
Frequency (Hertz)
1000 1200 1400 1600 1800 2000
1000 1200 1400
1600 1800 2000
meter (Figure 3) is required to generate 500 impuls-
es/KWH at I
sume that the maximum current is I
and the maximum voltage is V
utilize the full dynamic range of the CS5460, the
sensor gains can be calculated as:
where k
and current, respectively. The CS5460 is assumed
to be in the 30 mV
a shunt resistor.
The average Impulse Rate, IR, at the rated inputs is:
Since the pulse-rate register is defined in terms of
full-scale DC (0.25 V for the voltage channel and
0.05 V for the current channel in this case), IR will
need to be scaled before being placed in the
pulse-rate register. Define a voltage ratio, R
a current ratio, R
R
=
500 impulses
------------------------------- - I
v
KWH
and k
b
= 20 A
k
k
i
i
v
are the sensor gains for the voltage
=
i
, as:
=
RMS
30mV
------------------------- -
b
R
R
150mV
---------------------------- -
V
v
i
RMS
I
max
=
V
=
----------------- -
1000W
range to allow for the use of
max
1KW
RMS
0.05 Volt
---------------------- -
k
0.25 Volt
---------------------- -
k
i
v
RMS
I
and V = 230 V
V Volt
b
Amp
=
=
300
------------- -
3600s
max
1H
----------- -
2000
1
= 300 V
max
0.639 impulses
----------------------------------- -
= 100 A
CS5460
DS279PP5
RMS
RMS
s
v
. As-
, and
RMS
. To