EVAL-ADE7753EB View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-ADE7753EB' PDF : 38 Pages View PDF
ADE7753
2.42V, 1.21V, 0.6V
⋅ 1, ⋅ 2, ⋅ 4, REFERENCE
⋅ 8, ⋅ 16
{GAIN[2:0]}
V1P
V1
PGA1
ADC 1
{GAIN[4:3]}
HPF
DIGITAL
INTEGRATOR*
dt
V1N
V1
0.5V, 0.25V,
0.125V, 62.5mV,
31.3mV, 15.6mV,
0V
ANALOG
INPUT
RANGE
0x2851EC
0x00000
0xD7AE14
ADC OUTPUT
WORD RANGE
0x2851EC
CHANNEL 1
(CURRENT WAVEFORM)
DATA RANGE
0x000000
0xD7AE14
CURRENT RMS (IRMS)
CALCULATION
WAVEFORM SAMPLE
REGISTER
ACTIVE AND REACTIVE
POWER CALCULATION
50Hz
0x1EF73C
CHANNEL 1
(CURRENT WAVEFORM)
DATA RANGE AFTER
INTEGRATOR (50Hz)
0x000000
0xEI08C4
60Hz
0x19CE08
CHANNEL 1
(CURRENT WAVEFORM)
DATA RANGE AFTER
INTEGRATOR (60Hz)
0x000000
*WHEN DIGITAL INTEGRATOR IS ENABLED, FULL-SCALE OUTPUT DATA IS ATTENUATED
DEPENDING ON THE SIGNAL FREQUENCY BECAUSE THE INTEGRATOR HAS A –20dB/DECADE
FREQUENCY RESPONSE. WHEN DISABLED, THE OUTPUT WILL NOT BE FURTHER ATTENUATED.
Figure 51. ADC and Signal Processing in Channel 1
0xE631F8
02875-0-052
Channel 1 Sampling
The waveform samples can also be routed to the waveform
register (MODE[14:13] = 1,0) to be read by the system master
(MCU). In waveform sampling mode, the WSMP bit (Bit 3) in
the interrupt enable register must also be set to Logic 1. The
active, 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 Bits 11 and 12 of the mode register
(WAVSEL1,0). The output sample rate can be 27.9 kSPS, 14 kSPS,
7 kSPS, or 3.5 kSPS—see the Mode Register (0x09) section. The
interrupt request output, IRQ, signals a new sample availability
by going active low. The timing is shown in Figure 52. The 24-bit
waveform samples are transferred from the ADE7753 one byte
(eight bits) at a time, with the most significant byte shifted out
first. The 24-bit data-word is right justified—see the ADE7753
Serial Interface section. The interrupt request output IRQ stays
low until the interrupt routine reads the reset status register—
see the ADE7753 Interrupts section.
IRQ
SCLK
DIN
READ FROM WAVEFORM
0 0 0 01 HEX
Channel 1 RMS Calculation
Root mean square (rms) value of a continuous signal V(t) is
defined as
T
∫ VRMS = Vrms =
1 × V 2 (t)dt
T
(2)
0
For time sampling signals, rms calculation involves squaring the
signal, taking the average and obtaining the square root:
∑ VRMS = Vrms =
1 × N V 2 (i)
N i=1
(3)
The ADE7753 simultaneously calculates the rms values for
Channel 1 and Channel 2 in different registers. Figure 53 shows
the detail of the signal processing chain for the rms calculation
on Channel 1. The Channel 1 rms value is processed from the
samples used in the Channel 1 waveform sampling mode. The
Channel 1 rms value is stored in an unsigned 24-bit register
(IRMS). One LSB of the Channel 1 rms register is equivalent to
one LSB of a Channel 1 waveform sample. The update rate of
the Channel 1 rms measurement is CLKIN/4.
DOUT
SIGN
CHANNEL 1 DATA
(24 BITS)
Figure 52. Waveform Sampling Channel 1
02875-0-050
Rev. C | Page 24 of 60
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