CS5461 datasheet(24/45 Pages) CIRRUS

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CS5461

DS546F2

ative energy accumulation is reached in this regis-

ter, the CS5461 will issue either a positive or

negative energy pulse on the EOUT/EDIR pins.

After the pulse or pulses are issued, a certain resid-

ual amount of energy may be left over in this inter-

nal energy accumulation register. In this situation,

the residual energy is not lost or discarded, but rath-

er it is maintained and added to the energy that is

accumulated during the next update period.

5.2.2 Mechanical Counter Format

Setting the MECH bit in the Control Register to ‘1’

and the STEP bit to ‘0’ enables wide-stepping puls-

es for mechanical counters and similar discrete

counter instruments. In default mechanical mode

format, active-low pulses are 128 ms wide when

using a 4.096 MHz crystal and K = 1. When energy

is positive, the pulses appear on EOUT. When en-

ergy is negative, pulses appear on EDIR (see Fig-

ure 11). The pulse width is set in the Pulsewidth

able. It is up to the user to insure that pulses will not

occur at a rate faster than the 128 ms pulse dura-

tion, or faster than the mechanical counter can ac-

commodate. This is done by verifying that the

PulseRateE Register is set to an appropriate value.

Because in the default state the duration of each

pulse is set to 128 ms, the maximum output pulse

frequency

limited

~7.8 Hz

(for

MCLK/K = 4.096 MHz). For values of MCLK/K

different than 4.096 MHz, the duration of one pulse

is (128*4.096 MHz)/(MCLK/K) milliseconds.

5.2.3 Stepper Motor Format

Setting the STEP bit in the Control Register to ‘1’

and the MECH bit to ‘0’ transforms the EOUT and

EDIR pins into two-phase stepper motor outputs.

When an energy pulse occurs, one of the outputs

changes state. When the next energy pulse occurs,

the other output changes state. The direction the

motor will rotate is determined by the order of the

state changes. When energy is positive, EOUT will

lead EDIR. When energy is negative, EDIR will

lead EOUT (see Figure 12).

5.3 FOUT Pulse Output

In many metering applications, the pulse frequency

to power rate on the EOUT pin may be set to a rel-

atively low value, such that the pulse frequency is

on the order of 1-100 Hz at nominal power con-

sumption levels. However, calibration can take a

long time at such output frequencies. In order to re-

duce the time needed to verify the meter an extra

pulse frequency-to-power output is provided on the

FOUT pin. The pulse frequency-to-power rate can

128 ms

EOUT

EDIR

Positive Energy

Negative Energy

...

Figure 11. Mechanical Counter Format on EOUT and EDIR

EOUT

EDIR

Positive Energy

Negative Energy

...

Figure 12. Stepper Motor Format on EOUT and EDIR

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