CS5461 datasheet(23/45 Pages) CIRRUS

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CS5461

DS546F2

5. ENERGY PULSE OUTPUTS

5.1 Pulse-Rate Output (EOUT and EDIR)

EOUT and EDIR pins provide pulses which repre-

sent a predetermined magnitude of energy. With

MCLK = 4.096 MHz, and default settings, the

pulses will have an average frequency equal to the

frequency setting in the PulseRateE Register when

the input signals into the voltage and current chan-

nels cause full-scale readings in the Instantaneous

Voltage and Current Registers. When MCLK/K is

not equal to 4.096 MHz, the user should scale the

pulse-rate by a factor of 4.096 MHz / (MCLK / K)

to get the actual output pulse-rate.

5.2 Pulse Output for Normal Format,

Stepper Motor Format and Mechanical

Counter Format

EOUT and EDIR pins can be set in three different

output formats. The default setting is normal output

pulse format. When the pulse is set to either of the

other two formats, the time duration and/or the rel-

ative timing of the EOUT and EDIR pulses is var-

ied such that the pulses can drive either an

electro-mechanical counter or a stepper motor. The

ability to set the pulse output format to one of the

three available formats is controlled by setting cer-

tain bits in the Control Register.

5.2.1 Normal Format

In Normal format the EOUT and EDIR pulse out-

put format is illustrated in Figure 10. These are ac-

tive-low pulses of short duration. A positive energy

pulse is represented by a pulse on the EOUT pin

while the EDIR will remain high. A negative ener-

gy pulse is represented by synchronous pulses on

both the EOUT pin and the EDIR pin.

The pulse duration is an integer multiple of MCLK

cycles, approximately equal to 1/16 of the period of

the contents of the Pulse-Rate Register. However

for Pulse-Rate Register settings less than the sam-

pling rate (which is [MCLK/8]/1024), the pulse du-

ration remains constant and is equal to the duration

of the pulses when the Pulse-Rate Register is set to

[MCLK/K]/1024. The maximum pulse frequency

from the EOUT pin is therefore [MCLK / K] / 8.

When DCLK is not equal to 4.096 MHz, the pulse

duration can be predicted by using the pulse dura-

tion values in Table RR and dividing them by

(MCLK/K) / 4.096 MHz.

In Normal pulse output format, the number of puls-

es depends on the value of the PulseRateE Register

and on the amount of energy registered over the

most recent A/D sampling period. A running total

of the energy accumulation is maintained in an in-

ternal register inside the CS5461 (not available to

the user). After each A/D conversion cycle, the re-

sult in the Power Register is multiplied by the value

in the PulseRateE Register, and also by the value in

the TBC (Time-Base Calibration) Register, and

then added to this internal energy accumulation

EOUT

EDIR

Positive Energy Burst

Negative Energy Burst

. . .

Figure 10. Time-plot representation of pulse output for a typical burst of pulses (Normal For-

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