The operating voltage range for PSoC 6 is 1.7V to 3.6V. By default the PSoC 6 MCUs are designed to work at 1.1V (nominal) core voltage generated by an internal LDO regulator.
PSoC 3 and PSoC 6 are powerful MCUs purpose built for different types of application requirements. If you require a large array of analog options then PSoC 3 would be a good choice. If low power is the requirement, then PSoC 6 comes with 6 power modes, security and connectivity options, a best fit for IOT applications.
You can find the power specifications for
- PSoC 6 in Page#24 for various modes here: https://www.cypress.com/file/385921/download
- PSoC 3 in Page#32 for various modes here: https://www.cypress.com/file/127111/download