CS5460 查看數據表（PDF） - Cirrus Logic
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CS5460 Datasheet PDF : 34 Pages
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CS5460
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
0
200 400 600 800 1000 1200 1400 1600 1800 2000
Frequency (Hertz)
Figure 6. Voltage Input Filter Roll-off
meter (Figure 3) is required to generate 500 impuls-
es/KWH at Ib = 20 ARMS and V = 230 VRMS. As-
sume that the maximum current is Imax = 100 ARMS
and the maximum voltage is Vmax= 300 VRMS. To
utilize the full dynamic range of the CS5460, the
sensor gains can be calculated as:
kv
=
1---5----0---m-----V----R----M-----S
Vmax
=
-----1------
2000
ki
=
3---0----m-----V-----R---M----S-
Imax
=
300 µΩ
0.5
0
-0.5
-1
-1.5
-2
-2.5
0
200 400 600 800 1000 1200 1400 1600 1800 2000
Frequency (Hertz)
where kv and ki are the sensor gains for the voltage
and current, respectively. The CS5460 is assumed
to be in the 30 mVRMS range to allow for the use of
a shunt resistor.
The average Impulse Rate, IR, at the rated inputs is:
R
=
5---0----0--K--i--m-W----p--H-u---l-s---e--s-
( Ib V ) 1---10---K0----0-W--W----
3---6-1---0H---0---s-
≅
0---.--6---3---9-----i--m----p---u---l--s--e---s-
s
Figure 7. Current Input Filter Roll-off
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
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, Rv, and
a current ratio, Ri, as:
Rv
=
0---.--2---5-----V----o---l--t
kvV Volt
Ri
=
-0---.-0---5-----V----o---l--t
kiIb Amp
12
DS279PP5
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