Cirrus Logic CS5463 - Manual (Page 41)

CS5463
DS678F3 41
9. BASIC APPLICATION CIRCUITS
Figure 18 shows the CS5463 configured to measure
power in a single-phase, 2-wire system while operating
in a single-supply configuration. In this diagram, a shunt
resistor is used to sense the line current and a voltage
divider is used to sense the line voltage. In this type of
shunt-resistor configuration, the common-mode level of
the CS5463 must be referenced to the line side of the
power line. This means that the common-mode poten-
tial of the CS5463 will track the high-voltage levels, as
well as low-voltage levels, with respect to earth ground.
Isolation circuitry is required when an earth-ground-ref-
erenced communication interface is connected.
Figure 19 shows the same single-phase, two-wire sys-
tem with complete isolation from the power lines. This
isolation is achieved using three transformers: a general
purpose transformer to supply the on-board DC power;
a high-precision, low-impedance voltage transformer,
with very little roll-off/phase-delay, to measure voltage;
and a current transformer to sense the line current.
Figure 20 shows a single-phase, 3-wire system. In
many 3-wire residential power systems within the Unit-
ed States, only the two line terminals are available (neu-
tral is not available).
Figure 21 shows the CS5463
configured to meter a three-wire system with no neutral
available.
VA+ VD+
CS5463
0.1 µF 470 µF
500

470 nF
500
N
R
1
R
2
10

14
VIN+
9
VIN-
IIN-
10
15
16
IIN+
PFMON
CPUCLK
XOUT
XIN
Optional
Clock
Source
Serial
Data
Interface
RESET
17
2
1
24
19
CS
7
SDI
23
SDO
6
SCLK
5
INT
20
E1
0.1 µF
VREFIN
12
VREFOUT
11
AGND DGND
13 4
3
4.096 MHz
0.1 µF
10 k

5 k
L
R
Shunt
R
V-
R
I-
R
I+
ISO
L
ATION
120 VAC
Mech. Counter
Stepper Motor
or
22
21
C
I-
C
I+
C
Idiff
C
V-
C
V+
C
Vdiff
E2
Note:
Indicates common (floating) return.
Figure 18. Typical Connection Diagram (Single-phase, 2-wire – Direct Connect to Power Line)