CS5467 datasheet(18/46 Pages) CIRRUS

18 / 46 page

CS5467

DS714A1

ADVANCE RELEASE

All measurements are available as a percentage of full

scale. The format for signed registers is a two’s comple-

ment, normalized value between -1 and +1. The format

for unsigned registers is a normalized value between 0

and 1. A register value of

represents the maximum possible value.

At each instantaneous measurement, the CRDY bit will

be set in the Status Register, and the INT pin will be-

come active if the CRDY bit is unmasked in the Mask

. At the end of each computation cycle, the

DRDY bit will be set in the Status Register, and the INT

pin will become active if the DRDY bit is unmasked in

the Mask Register. When these bits are asserted, they

must be cleared before they can be asserted again.

If the Cycle Count Register (N) is set to 1, all output cal-

culations are instantaneous, and DRDY, like CRDY, will

indicate when instantaneous measurements are fin-

ished. Some calculations are inhibited when the cycle

count is less than 2.

Epsilon (

ε) is the ratio of the input line frequency (f

i) to

the sample frequency (fs) of the ADC.

where fs = MCLK / (K x 1024). With MCLK = 4.096 MHz

and clock divider K = 1, fs = 4000 Hz. For the two

most-common line frequencies, 50 Hz and 60 Hz

and

respectively. Epsilon is used to set the gain of the 90°

phase shift (IIR) filter for the average reactive power cal-

culation.

5.5 Energy Pulse Output

The CS5467 provides three output pins for energy reg-

istration. By default, E1 is used to register average ac-

tive energy measured on channels 1 and 2, E3 is used

to register average reactive energy measured on chan-

nels 1 and 2, and E2 indicates the sign of both active

and reactive energy. (See Figure 2. Timing Diagram for

E1, E2, and E3

on page 13.)

The E1 pulse output is designed to indicate the average

active energy measured on channels 1 and 2. The E2

pin can be used to register average apparent energy

measured on channels 1 and 2 or to indicate the sign of

energy. Table 2 defines the pulse output mode, which is

controlled by bit E2MODE in the Operational Mode Reg-

ister.

The E3 pin can be set to register average reactive ener-

gy measured on channels 1 and 2 (default), PFMON,

voltage channel sign, or average apparent energy mea-

sured on channels 1 and 2. Table 3 defines the pulse

output format, which is controlled by bits E3MODE[1:0]

in the Operational Mode Register.

The pulse output frequencies of E1, E2, and E3 are di-

rectly proportional to the power calculated from the input

signals. The value contained in the PulseRateE Regis-

ter

is the ratio of the frequency of energy-output pulses

to the number of samples, at full scale, which defines

the average frequency for the output pulses. The pulse

width, tpw in Figure 2, is an integer multiple of MCLK cy-

cles approximately equal to:

If MCLK = 4.096 MHz and K = 1 then tpw ≅ 0.25 ms.

5.5.1 Active Energy

The E1 pin produces active-low pulses with an output

frequency proportional to the average active power

measured on channels 1 and 2. The E2 pin is the ener-

gy direction indicator. Positive energy is represented by

E1 pin falling while the E2 is high. Negative energy is

represented by the E1 pin falling while the E2 is low.

The E1 and E2 switching characteristics are specified in

Figure 2. Timing Diagram for E1, E2, and E3 on page

13.

–

()

------------------------

0.99999988

ε f

i fs

⁄

ε 50 Hz 4000 Hz

⁄

0.0125

ε 60 Hz 4000 Hz

⁄

0.015

E2MODE

E2 Output Mode

Sign of Energy

Apparent Energy

Table 2. E2 Pin Configuration

E3MODE1

E3MODE0

E3 OutPut Mode

Reactive Energy

PFMON

Voltage Channel Sign

Apparent Energy

Table 3. E3 Pin Configuration

sec

()

( MCLK/K ) / 1024

-------------------------------------

≅

CS5467 Datasheet(PDF) 18 Page - Cirrus Logic

CS5467 Datasheet(HTML) 18 Page - Cirrus Logic

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

Datasheet Download

Link URL