CS5464-IS 查看數據表（PDF） - Cirrus Logic
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CS5464-IS Datasheet PDF : 46 Pages
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CS5464
(MCLK), with frequency: Under default conditions and
Computation Cycle
=
O------W------R---
N
with K = 1, N = 4000, and MCLK = 4.096 MHz – the
OWR = 4000 and the Computation Cycle = 1 Hz.
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
(223 – 1)
-----------------------
223
=
0.99999988
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
Register. 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 2, all output cal-
culations are instantaneous, and DRDY, like CRDY, will
indicate when instantaneous measurements are fin-
ished. The Cycle Count Register (N) must be ≥ 2.
Epsilon (ε) is the ratio of the input line frequency (fi) to
the sample frequency (fs) of the ADC.
ε = fi ⁄ fs
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
ε = 50 Hz ⁄ 4000 Hz = 0.0125
and
ε = 60 Hz ⁄ 4000 Hz = 0.015
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 CS5464 provides three output pins for energy reg-
istration. By default, E1 is used to register active energy,
E3 is used to register reactive energy, 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 Active
Energy. The E2 pin can be used to register Apparent
Energy, to indicate a tamper detection has occurred, or
to indicate the sign of energy. Table 3 defines the pulse
output mode, which is controlled by bit E2MODE[1:0] in
the Operational Mode Register.
E2MODE1 E2MODE0
0
0
0
1
1
0
1
1
E2 Output Mode
Sign of Energy
Apparent Energy
Tamper Indicator
Reserved
Table 3. E2 Pin Configuration
The E3 pin can be set to register Reactive Energy (de-
fault), PFMON, Voltage Channel Sign, or Apparent En-
ergy. Table 4 defines the pulse output format, which is
controlled by bits E3MODE[1:0] in the Operational
Mode Register.
E3MODE1
0
0
1
1
E3MODE0
0
1
0
1
E3 OutPut Mode
Reactive Energy
PFMON
Voltage Channel Sign
Apparent Energy
Table 4. E3 Pin Configuration
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:
tp w ( sec )
≅
------------------1------------------
( MCLK/K ) / 1024
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 active power. The E2 pin
is the energy direction indicator. Positive energy is rep-
resented 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
18
DS682PP1
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