ade7566 Analog Devices, Inc., ade7566 Datasheet - Page 44

• Manufacturer Part Number: ade7566
• Description: Single-phase Energy Measurement Ic With 8052 Mcu, Rtc, And Lcd Driver
• Manufacturer: Analog Devices, Inc.

ADE7566/ADE7569
Voltage Channel ADC
Figure 44 shows the ADC and signal processing chain for the
voltage channel. In waveform sampling mode, the ADC outputs
a signed, twos complement, 24-bit data-word at a maximum
of 25.6 kSPS (MCLK/160). The ADC produces an output code
that is approximately between 0x28F5 (+10,485d) and 0xD70B
(−10,485d).
Channel Sampling
The waveform samples of the current ADC and voltage ADC
can also be routed to the waveform registers to be read by the
MCU core. The active, reactive, apparent power, and energy
calculation remain uninterrupted during waveform sampling.
When in waveform sampling mode, one of four output sample
rates can be chosen by using the DTRT[1:0] bits of the WAVMODE
register (see Table 34). The output sample rate can be 25.6 kSPS,
12.8 kSPS, 6.4 kSPS, or 3.2 kSPS. If the WFSM enable bit is set
in the Interrupt Enable 3 SFR (MIRQENH, 0xDB), the 8052
core has a pending ADE interrupt. The sampled signals selected
in the WAVMODE register are latched into the Waveform SFRs
when the waveform high byte (WAV1H or WAV2H) is read.
The ADE interrupt stays active until the WFSM status bit is
cleared (see the Energy Measurement Interrupts section).
*WHEN DIGITAL INTEGRATOR IS ENABLED, FULL-SCALE OUTPUT DATA IS ATTENUATED
0.5V, 0.25V,
0.125V, 62.5mV,
31.3mV
DEPENDING ON THE SIGNAL FREQUENCY BECAUSE THE INTEGRATOR HAS A –20dB/DECADE
FREQUENCY RESPONSE. WHEN DISABLED, THE OUTPUT IS NOT FURTHER ATTENUATED.
V2
0V
V
V
P
N
V2
ANALOG
INPUT
RANGE
PGA2
×1, ×2, ×4,
×8, ×16
{GAIN[7:5]}
0xD70B
0x28F5
0x0000
REFERENCE
Figure 44. ADC and Signal Processing in Voltage Channel
ADC
VOLTAGE CHANNEL
WAVEFORM
DATA RANGE
Rev. 0 | Page 44 of 136
HPF
ACTIVE AND REACTIVE
POWER CALCULATION
f
–3dB
MODE1[6]
WAVEFORM SAMPLE
REGISTER
VOLTAGE PEAK DETECT
di/dt CURRENT SENSOR AND DIGITAL
INTEGRATOR FOR THE ADE7569
A di/dt sensor, a feature available for the AD7569, but not for
the AD7566, detects changes in the magnetic field caused by ac
currents. Figure 45 shows the principle of a di/dt current sensor.
The flux density of a magnetic field induced by a current is
directly proportional to the magnitude of the current. The
changes in the magnetic flux density passing through a conductor
loop generate an electromotive force (EMF) between the two
ends of the loop. The EMF is a voltage signal that is proportional
to the di/dt of the current. The voltage output from the di/dt
current sensor is determined by the mutual inductance between
the current-carrying conductor and the di/dt sensor. The current
signal needs to be recovered from the di/dt signal before it can
be used. An integrator is therefore necessary to restore the
signal to its original form.
VOLTAGE RMS (V
CALCULATION
LPF1
= 63.7Hz
rms
Figure 45. Principle of a di/dt Current Sensor
0x1DD0
0xDFC9
0xE230
ZX DETECTION
0x0000
0x2037
0x0000
)
ZX SIGNAL
DATA RANGE FOR 50Hz SIGNAL
ZX SIGNAL
DATA RANGE FOR 60Hz SIGNAL
MAGNETIC FIELD CREATED BY CURRENT
(DIRECTLY PROPORTIONAL TO CURRENT)
+ EMF (ELECTROMOTIVE FORCE)
– INDUCED BY CHANGES IN
MAGNETIC FLUX DENSITY (di/dt)