CS5461A datasheet(39/44 Pages) CIRRUS

39 / 44 page

CS5461A

DS661F2

9. BASIC APPLICATION CIRCUITS

Figure 15 shows the CS5461A 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 CS5461A must be referenced to the line side of the

power line. This means that the common-mode poten-

tial of the CS5461A will track the high-voltage levels, as

well as low-voltage levels, with respect to earth ground

potential. Isolation circuitry is required when an earth-

ground-referenced communication interface is connect-

ed.

Figure 16 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 17 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 18 shows the CS5461A

configured to meter a three-wire system with no neutral

available.

VA+

VD+

CS5461A

0.1 µF

470 µF

500

Ω

470 nF

500

Ω

VIN+

VIN-

IIN-

IIN+

PFMON

CPUCLK

XOUT

XIN

Optional

Clock

Source

Serial

Data

Interface

RESET

SDI

SDO

SCLK

INT

0.1 µF

VREFIN

VREFOUT

AGND

DGND

4.096 MHz

0.1 µF

10 k

Ω

Shunt

V-

I-

I+

120 VAC

Mech. Counter

Stepper Motor

I-

I+

Idiff

CV-

CV+

CVdiff

Note:

Indicates common (floating) return.

Figure 15. Typical Connection Diagram (Single-phase, 2-wire – Direct Connect to Power Line)

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