Datasheet

ADE7880 Data Sheet
Rev. A | Page 40 of 104
Table 12. Settling Time for I RMS Measurement
Integrator Status 50 Hz Input Signals
the integrator is enabled, that is, when Bit 0 (INTEN) in the
CONFIG register is set to 1, the equivalent rms value of a full-
scale sinusoidal signal at 50 Hz is 3,759,718 (0x395E66) and at
60 Hz is 3,133,207 (0x2FCF17).
60 Hz Input Signals
Integrator Off 580 ms 580 ms
Integrator On 700 ms 700 ms
The accuracy of the current rms is typically 0.1% error from
the full-scale input down to 1/1000 of the full-scale input when
PGA = 1. Additionally, this measurement has a bandwidth of
3.3 kHz. It is recommended to read the rms registers synchronous
to the voltage zero crossings to ensure stability. The
IRQ1
inter-
rupt can be used to indicate when a zero crossing has occurred
(see the section). shows the settling time for
the I rms measurement, which is the time it takes for the rms
register to reflect the value at the input to the current channel
when starting from 0.
Interrupts Table 12
As stated in the Current Waveform Gain Registers section, the
serial ports of the ADE7880 work on 32-, 16-, or 8-bit words.
Similar to the register presented in Figure 64, the AIRMS,
BIRMS, CIRMS, NIRMS 24-bit signed registers are accessed as
32-bit registers with the eight MSBs padded with 0s.
31 24 23 0
24-BIT NUMBER0000 0000
10193-039
Figure 64. 24-Bit AIRMS, BIRMS, CIRMS and NIRMS Registers Transmitted as
32-Bit Words
0xAEB86F =
–5,326,737
0x514791 =
5,326,737
0V
CURRENT SIGNAL FROM
HPF OR INTEGRATOR
(IF ENABLED)
LPF
x
2
2
7
xIRMSOS[23:0]
xIRMS[23:0]
10193-040
Figure 65. Current RMS Signal Processing