ADE7880
Data Sheet
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).
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 Interrupts section). Table 12 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.
Table 12. Settling Time for I RMS Measurement
Integrator Status 50 Hz Input Signals 60 Hz Input Signals
Integrator Off
580 ms
580 ms
Integrator On
700 ms
700 ms
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
0000 0000
24-BIT NUMBER
Figure 64. 24-Bit AIRMS, BIRMS, CIRMS and NIRMS Registers Transmitted as
32-Bit Words
xIRMSOS[23:0]
27
CURRENT SIGNAL FROM
HPF OR INTEGRATOR
x2
(IF ENABLED)
LPF
xIRMS[23:0]
0x514791 =
5,326,737
0V
0xAEB86F =
–5,326,737
Figure 65. Current RMS Signal Processing
Rev. A | Page 40 of 104