78M6610+LMU Data Sheet
Current Input Configuration
The 78M6610+LMU supports multiple analog input configurations for determining the two load currents in
a split-phase AC circuit. The device measures the current of any two conductors and uses this
information to derive the load currents shown below.
IA
Conductor A
IA= - IB - IN
IB= - IA - IN
IN
Conductor N
Conductor B
IB
Figure 13. Current Input Configuration
Each calculated load current (IA and IB) is derived from the following function of the current input slots
(S1 and S3) and 2 pairs of multiplier values (M1 and M3). This function derives source currents IA and IB
by summing S1 x M1 and S3 x M3.
M1
S1
S3
Ix
+
M3
Figure 14. Current Computation
The user sets the multiplier values for each current source in the CONFIG register using the model where
a one (1) value adds the input, a two (2) value adds two of the input, a minus one (-1) value subtract the
input, a zero (0) value does not include the input.
CONFIG Bits
Multiplier
7:6
5:4
3:2
1:0
M3
M1
M3
M1
Source
IB
IA
There are four choices for every M value as shown below.
Bit Values
00
01
10
11
M (multiplier) Value
-1
0
1
2
The output registers IA and IB are automatically scaled by a factor of 0.5 if M1 and M3 are both nonzero.
For example, by setting the multiplier bits as follows:
퐼퐵 = +1 ∗ 푆1 ꢀ 1 ∗ 푆3
The effective content of the Vc register would result in:
(
)
+1 ∗ 푆1 + (ꢀ1 ∗ 푆3)
푉푐 =
2
This scaling is done to prevent the output register from overflowing.
23
Rev 0
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
