Current Consumption Estimation for MSP430

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How to Estimate Current Consumption for the MSP430

There are many configurations for the MSP430 in terms of operating frequency, supply voltage, operating mode, and active peripherals. Because of this only some combinations' current consumption characteristics are enumerated in the device datasheet. For cases that are not listed, estimation is needed to determine the expected consumption.


To estimate the current consumption for the MSP430, the device datasheet lists numbers for each operating mode with certain frequencies and operating voltages. Additionally each peripheral's current consumption is listed separately in it's corresponding section of the datasheet. Adding these values as needed can give a good estimate on current consumption but experimental testing is needed to determine the actual consumption your peripheral configuration will exhibit in the field.

Reducing Current Consumption for the MSP430

Turning off as much peripherals as possible when not in use will lower the current consumption. To estimate the current consumption for the MSP430, the device datasheet lists numbers for each operating mode with certain frequencies and operating voltages. Additionally each peripheral's current consumption is listed separately in it's corresponding section of the datasheet. Adding these values as needed can give a good estimate on current consumption but experimental testing is needed to determine the actual consumption your peripheral configuration will exhibit in the field.

Use ULP Advisor to identify areas in your code for power improvement. ULP Advisor automatically checks your code against a ULP checklist. During development, use the ULP rule checklist to ensure low power usage in the program. 


We have a couple of related k-base articles on this which you may find useful:

1. Problem: MSP430: Supply current is higher than expected! --> Especially in low power modes the supply current is higher than expected!


Solution: One issue that can lead to higher supply current consumption than expected is unused inputs. To prevent this, all unused I/O pins must be left open, switched to port function and their direction configured as outputs. The correct termination of all unused pins is listed in the Connection of Unused Pins section of the System Resets, Interrupts, and Operating Modes chapter of the device user`s guide.

Hint: It is good design practice to connect an unused Test/Vpp pin to Vss(GND). If this pin needs to be routed to the JTAG-connector for debugging, an external pull-down resistor will improve EMI/EMC performance.

The original article can be found here

2. Problem: MSP430: Current consumption is high in Low Power modes -->Why is the supply current higher than expected especially in low power modes?

-->Why is the supply current higher than expected especially in low power modes?

Solution:

A few things to check for low current consumption are:

a) All unused I/O pins must be left open, switched to port function and their direction configured as outputs. The correct termination of all unused pins is listed in the Connection of Unused Pins section of the System Resets, Interrupts, and Operating Modes chapter of the device user`s guide.

a) Is the ADC reference turned off? Please see Datasheet

b) Is the comparator turned off? Please see Datasheet

c) If using XT2, is XT2 turned off?

d) Verify the connections on MSP430’s inputs even when in LPM mode?

e) Is the device clean (flux, unwanted solder)?

This article can be found here