SLAU846B June 2023 – November 2024 MSPM0G1105 , MSPM0G1106 , MSPM0G1107 , MSPM0G1505 , MSPM0G1506 , MSPM0G1507 , MSPM0G3105 , MSPM0G3106 , MSPM0G3107 , MSPM0G3505 , MSPM0G3506 , MSPM0G3507
Several direct clock connections are made in the device to support specific analog functionality:
Direct Connections to ADCs
In addition to receiving ADCCLK to set the sampling window, the ADC modules also receive the direct output of SYSOSC. The SYSOSC direct output to the ADCs is used by the charge pump logic in the ADC modules. SYSOSC can be configured at any frequency to support this function. The ADC supports requesting SYSOSC automatically before a conversion, so there is not a requirement for application software to ensure that SYSOSC is running before triggering an ADC conversion.
Direct Connections to OPAs
The SYSOSC direct clock connection to the OPAs, if present, enable all OPA operating modes to be used even when the peripheral bus clock (ULPCLK) is running at a lower frequency than what is required by the OPA. Certain OPA modes require that SYSOSC be running at 32MHz. See the OPA section for clocking details. Configuration of SYSOSC to a frequency which supports the selected OPA mode is the responsibility of the application software. If the OPA is enabled and configured for a mode which requires SYSOSC to be running at a certain frequency, and software has not configured SYSOSC to run at this frequency, an OPAMPCLKERR will be asserted in the CLKSTATUS register in SYSCTL and the OPA can not function properly.
Direct Connections to the PMU Analog Mux VBOOST Circuit
Both the SYSOSC and the LFCLK are connected directly to the analog mux VBOOST circuit in the PMU, which is used to boost the performance of the analog muxes used by the COMPs, OPAs, and GPAMP. The VBOOST circuit is enabled automatically when a peripheral requires it for correct operation. It is the responsibility of the application software to ensure that the SYSOSC or LFCLK are enabled to support correct operation of the VBOOST circuit. If the VBOOST circuit requires SYSOSC or LFCLK, and the clock is not available, an ANACLKERR is asserted in the CLKSTATUS register in SYSCTL. SYSCTL can also be configured to raise a SYSCTL interrupt when ANACLKERR is asserted, to alert the application that a COMP, OPA, or the GPAMP can not be functioning properly as expected.