CS5471 datasheet(7/14 Pages) CIRRUS

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CS5471

2. GENERAL DESCRIPTION

The CS5471 is designed for single-phase power

meter applications and interfaces to a current trans-

formers or shunt to measure current, and a resistive

divider or transformer to measure voltage.

The CS5471 combines two

∆Σ modulators and

decimation filters, one channel assigned for current

input that has programmable input gain amplifiers,

and one channel assigned for voltage input.

The CS5471 includes two decimation filters that

output data at a 2000 Hz or 4000 Hz output word

rate (OWR) when the input frequency at XIN =

4.096 MHz.

The device outputs data on a serial output port.

2.1

Theory of Operation

The CS5471 is designed to operate from a single

+3V supply and provides a ±40 mV and ±800 mV

input range for the current channel and ±800 mV

range for the voltage channel. These voltages rep-

resent the maximum zero-to-peak voltage levels

that can be presented to the inputs. The CS5471 is

designed to accommodate common mode + signal

levels from VA- to VA+. Figure 2 illustrates the

CS5471 typical inputs and power supply connec-

tions.

2.2

Performing Measurements

The converter outputs are transferred in 16-bit

signed (two’s complement) data formats as a per-

VA+

VD+

VIN +

VIN-

IIN+

IIN -

AGND

DGND

REFIN

REFOUT

Optional

External

Reference

PHASE

-2 V

PHASE

VA-

+3 V

1.2 V

NOTE: Current input channel

actually measures voltage.

Figure 2. Typical Connection Diagram

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