Cirrus Logic CS5480 - Manual (Page 23)

CS5480
DS980F3 23
5.5 Meter Configuration Modes
There are two distinct meter configuration modes in the
CS5480 that affect how the total active, reactive, and ap-
parent power calculations are performed. The CS5480
has power results for each current channel as well as total
power registers (P
SUM
, Q
SUM
, and S
SUM
). The total power
registers are calculated from either one or both channels,
depending on the meter configuration modes. See Table 2
for power calculations in each mode.
The Meter Configuration (MCFG) bits in the configuration
(Config2) register set the meter configuration modes. For
each meter mode, the current channels are interpreted dif-
ferently. In the one voltage and two line currents (1V – 2I)
mode, the CS5480 treats the two currents as individual
contributors to the overall power. In the one voltage, one
line current, and one neutral current (1V – 1I – 1N) mode,
the currents are treated as duplicate copies of the same
load current, and the total power is calculated from the
highest current or the one the customer has specified. The
MCFG multiplexers in Figure 14 show the data path for
both modes.
Table 2. Meter Configuration Modes
2 ÷ VF
RMS
P2
I2 RMS 1
0
I1
RMS
P1 N ÷
N ÷  N
 N
1
0
P2
AVG
P1
AVG
01
00
1
0
P
SUM
2 ÷
Q2
Q1 N ÷
N ÷
 N
 N
Q2
AVG
Q1 AVG
01
00
1
0
Q SUM
2 ÷
S2
S1
01
00
1
0
S
SUM
VFIX
(Config2)
MCFG[1:0]
(Config2)
ICHAN
(IHOLD = 1)
Figure 14. Channel Selection and Tamper Protection Flow
Meter
Mode MCFG
[1:0]
Total Power
Calculations
1V-2I 01
2
,
2
,
2
1V-1I-1N
(I1
RMS
> I2
RMS
)*
(P1
AVG
> P2
AVG
)*
00
(Default)
1V-1I-1N
(I1
RMS
< I2
RMS
)*
(P1
AVG
< P2
AVG
)*
00
(Default)