78M6610+LMU Data Sheet
Voltage Input Configuration
The 78M6610+LMU supports multiple analog input configurations for determining the three potential
voltage sources in a split-phase circuit. The device measures the voltage difference between any two
references and uses this information to derive the voltages VA, VB, and VC as shown below.
Conductor A
+
+
VA
VB
-
-
Conductor N
Conductor B
VC
+
-
Figure 9. Voltage Input Configuration
Each calculated voltage source (VA, VB, and VC) is derived from the following user configurable function
of the voltage input multiplexer slots (S0, S2) and three pairs of multiplier values (M0, M2). This function
derives source voltages VA, VB, and VC by summing S0 x M0 and S2 x M2.
M0
S0
S2
Vx
+
M2
Figure 10. Voltage Computation
The user sets the multiplier values M0 and M2 for each voltage 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
19:18 17:16 15:14 13:12 11:10
M2 M0 M2 M0 M2
9:8
M0
Source
VC
VB
VA
There are four choices for every M value as shown below.
Multiplier Bits
00
01
10
11
M (multiplier) Value
-1
0
1
2
The output registers VA, VB, and VC are automatically scaled by a factor of 0.5 if M0 and M2 are both
nonzero.
For example, by setting the multiplier bits as follows:
푉푐 = +1 ∗ 푆0 ꢀ 1 ∗ 푆2
The effective content of the Vc register would result in:
(
)
+1 ∗ 푆0 + (ꢀ1 ∗ 푆2)
푉푐 =
2
This scaling is done to prevent the output register from overflowing.
20
Rev 0
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
