SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
The analog-to-digital converters (ADC) and buffered digital-to-analog converters (DAC) share a common reference circuit. If needed, an application using one or more of these modules can optimize power-up time by taking advantage of the shared reference. Once one of the modules using the shared reference has been initialized in internal reference mode, the power-up time for subsequent modules can be optimized by subtracting the reference power-up time from the minimum power-up time requirement.
For instance, if ADCA requires tADCPUINT to power up in internal reference mode, and tADCPUEXT to power up in external reference mode, the application does not need to wait tADCPUINT to power up a second ADC instance such as ADCC in internal reference mode. In this case, the application can simply wait for tADCPUEXT after powering up ADCC, even though both ADCs are used in internal reference mode. In the same scenario, if the application wished to use DACA in internal reference mode, the required wait time after power-up is tDACPUEXT, not the longer tDACPUINT.
There is also a wait time associated with power-up in internal reference mode when switching between 2.5V and 3.3V range. See the device data sheet for wait time values.