MAX 10 Plus User
Manual
55
May 31, 2019
Figure 6-1 Block Diagram of Power Monitor Demonstration
illustrates the idea of how to measure the current for each power rail. A current sense
resistor
R
SENSE
is added to the path of each power rail. LTC2990 measures the voltage difference
(V1-V2) and calculate the current based on the formula below:
Current = (V1-V2) /
R
SENSE
The power consumption can be calculated by the following formula:
Power Consumption = VCC x Current = VCC x (V1-V2) /
R
SENSE
Figure 6-2 Schematic of Current Sense
shows the register content of LTC2990. The voltage difference (V1-V2) measured are
written into two registers, MSB (register 06h) and LSB (register 07h). The most significant bit (7
th
bit) of MSB register is the data_valid bit, which indicates whether the current register content has
been accessed since the result was last written to the register. This bit will be “set” i.e. 1 when the
register content is renewed and “cleared” i.e. 0 when the register content is accessed. Bit 6 of the