SLAA833A May   2018  – October 2019 MSP430FR2353 , MSP430FR2355

 

  1.   How to Use the Smart Analog Combo in MSP430™ MCUs
    1.     Trademarks
    2. 1 Introduction
      1. 1.1 Smart Analog Combo (SAC) Concept
      2. 1.2 Single-Supply Amplifier Design Consideration
      3. 1.3 Smart Analog Combo Driver Library
    3. 2 Smart Analog Combo Operation Modes
      1. 2.1 General Purpose Mode
        1.       Example 1. Code Example for Smart Analog Combo General-Purpose Mode
      2. 2.2 Buffer Mode
        1.       Example 2. Code Example for Smart Analog Combo Buffer Mode
      3. 2.3 Noninverting PGA Mode
        1.       Example 3. Code Example for Smart Analog Combo Noninverting PGA Mode
      4. 2.4 Inverting PGA Mode
        1.       Example 4. Code Example for Smart Analog Combo Inverting PGA Mode
      5. 2.5 DAC Mode
        1.       Example 5. Code Example for Smart Analog Combo DAC Mode
    4. 3 Smart Analog Combo Interconnection Configuration
      1. 3.1 Smart Analog Combo Cascading
      2. 3.2 Smart Analog Combo Interconnection With Other Peripherals
    5. 4 Smart Analog Combo Use Cases in Sensing Applications
      1. 4.1 Use Smart Analog Combo in Smoke Detector
      2. 4.2 Use Smart Analog Combo in Current Loop
    6. 5 References
  2.   Revision History

2.3 Noninverting PGA Mode

Figure 6 shows the SAC noninverting PGA mode. In this mode, signal can be amplified without inverting. This is useful for single-supply amplifier where negative voltage is not allowed. External feedback is not necessary that the internal configurable resistor ladder determines the amplifier gain. There are 8 different gain settings from 1x to 33x.

SLAU445_SAC_NONINV.gifFigure 6. Smart Analog Combo Noninverting PGA Mode

As the red highlighted part in Figure 6 shows, the signal input can be selected from the positive port OAx+ or a paired OA. The OA negative port must select PGA input (NSEL = 01b), and the PGA MSEL is set to ground (MSEL = 10b).SAC gain is configured by GAIN bits in SACxPGA control register. Example 3 shows one code sequence of configuring SAC into noninverting PGA mode with driver library API functions.