How do I use the internal voltage regulator in C8051T6xx MCUs?
The VDD pin on C8051T6xx devices can accept voltages from 1.8V to 3.6V. An on-chip voltage regulator, which is enabled by default, will regulate all input voltages from 3.6V to 1.8V down to 1.8V. If an external regulator applies 1.8V to VDD, the on-chip regulator can be switched to bypass mode by setting the BYPASS bit in the REG0CN register.
Important usage notes regarding the on-chip regulator:
· Setting the BYPASS bit in a system where VDD is not being supplied by an external 1.8V regulator can cause permanent damage to the device
· The voltage present on VDD controls the logic high output voltage on port pins
· The ADC on C8051T6xx devices can use the output of the internal voltage regulator as a voltage reference
· The on-point temperature calibration constants stored on-chip are measured using the output of the internal voltage regulator as the ADC's voltage reference
· The regulator can be configured to switch off when the device goes into stop mode, which will lower current draw
· A “power controller” in the regulator can be switched on to lower current draw in devices with system clock frequencies of 2MHz or lower