SLAAE72 December   2022 MSPM0L1105 , MSPM0L1106 , MSPM0L1303 , MSPM0L1304 , MSPM0L1304-Q1 , MSPM0L1305 , MSPM0L1305-Q1 , MSPM0L1306 , MSPM0L1306-Q1 , MSPM0L1343 , MSPM0L1344 , MSPM0L1345 , MSPM0L1346

 

  1.   Abstract
  2.   Trademarks
  3. 1Overview
  4. 2Low-Power Features in PMCU
    1. 2.1 Overview
      1. 2.1.1 Power Domains and Power Modes
    2. 2.2 Power Management (PMU)
      1. 2.2.1 Supply Supervisors
      2. 2.2.2 Peripheral Power Control
      3. 2.2.3 VBOOST for Analog Muxes
    3. 2.3 Clock Module (CKM)
      1. 2.3.1 Oscillators
      2. 2.3.2 Clocks
      3. 2.3.3 Asynchronous Fast Clock Requests
      4. 2.3.4 Shutdown Mode Handling
  5. 3Low-Power Optimization
    1. 3.1 Low-Power Basics
    2. 3.2 MSPM0 Low-Power Feature Use
      1. 3.2.1 Low-Power Modes
      2. 3.2.2 System Clock and Peripheral Operation Frequency
      3. 3.2.3 I/O Configuration
      4. 3.2.4 Event Manager
      5. 3.2.5 Analog Peripheral Low-Power Features
      6. 3.2.6 Run Code From RAM
    3. 3.3 Software Coding Strategies
    4. 3.4 Hardware Design Strategies
  6. 4Power Consumption Measurement and Evaluation
    1. 4.1 Current Evaluation
    2. 4.2 Current Measurement
      1. 4.2.1 Current Measurement

3.4 Hardware Design Strategies

MCU power supply

The MSPM0 supports operating across 1.62 V to 3. 6V. To reach lower power consumption, Users can supply a voltage no lower than 1.62 V to MCU. However, attention need to be paid to some peripheral working limit, such as internal reference. When power lower than 2.7 V, only 1.4-V reference can be used and 2.5-V reference cannot be used.

Resistors

Resistors are common used in the circuit, which is for current limitation or voltage divider. Please ensure the selected resistor value is large enough, after considering the drive strength and voltage setting time. More attention needs to be paid for the voltage divider, which may have constant leakage current. For some low-cost application, you can use the controllable GPIO as the voltage source.

Capacitors

More types and sizes of capacitors will be used in the circuit than resistors. All capacitors will have a small leakage current loss. Aluminum electrolytic and tantalum capacitors can provide a large capacitance with a large leakage current, which typical value is uA level and closed to the standby current of MSPM0. While ceramic, foil, capacitors have small capacity and leakage currents, which typical value is nA level.

Generally, capacitors with high capacitance values tend to have higher leakage current. capacitors with higher voltage rating have lower leakage but also have less capacitance in relation to package size. Besides, applying high voltage and high working temperature will also increase the leakage current. Remember to refer to the capacitor data sheet, in the hardware design.

However, there is still some cases to typical use large capacitors. If the users care more about the peak current, large capacitors can be used to cut down peak current and spread it to static current. In this condition, users need to trade off the peak current against the static current.

Power IC

Switching regulators can reach high efficiency at heavy load. However, they have a low efficiency and normally with high power noise at weak load. For linear regulators, its efficiency relies on the input and output voltage setting and it has less power noise and cost. For some battery applications, if the battery input voltage all covered by the MCUs, removing power IC could be a good choice. Users need to do the selection according to their application.

Crystals

Normally, using an external low frequency 32-kHz crystal can reach lower power consumption than using the internal one in lower power modes. When using external crystals, remember to refer to the crystal data sheet for appropriate load capacitor values and layout rules. Improper capacitors will cause crystal frequency shift and even vibration initiation failure.

For using external high-frequency crystal, as it is not possible to disable SYSOSC when using a different high frequency clock to source MCLK (such as HFCLK or the PLL), the power consumption will even be higher than using internal high frequency crystal. This is because SYSOSC is used by SYSCTL logic when MCLK is sourced from HFCLK or the PLL.